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Author Topic: AFM Question - 2011 Avalanche  (Read 4124 times)
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EMSDC
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« on: 01/16/13 04:06 PM »

I have a 2011 Avalanche with 18000 miles and have the rough idle at stops as others have mention (no service codes). The question I have is while driving in city conditions 0-35 mph with stops, when the AFM shifts downs from 8 to 4 the entire ride of the vehicle changes as in not as smooth when using 8 cylinders. It seems like it really struggles while in the 4 cylinders during city driving.

Anybody in the club have the same?   Maybe it's me, but I sure didn't notice it when I bought it new with 5100 miles!
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« Reply #1 on: 01/21/13 11:01 AM »

I have a 2011 as well. I can't tell the difference when it shifts to 4 cylinder unless I look at the DIC. The change is totally transparent city, highway or towing. I'm not much help, but know it should ride smooth in 4 or 8 cylinder.
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« Reply #2 on: 05/02/13 10:40 AM »

If the change is seamless, you must still be running the stock exhaust.  I think it's a pain in the ass, especially at low speeds, don't like it, it feels like a miss.  I'm turning mine off.
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« Reply #3 on: 05/02/13 06:10 PM »

Yes, I have stock exhaust. Does the ride / smoothness change with a cat back?
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« Reply #4 on: 05/02/13 06:50 PM »

I was vaguely aware of an idle problem and possible related TSB for the vehicles with AFM.

I took my 2010 in for a late check up with 35,750 miles and the first thing my service guy asked was if I was having a problem with rough idle at freeway off ramps.

Curiously, I responded yes as I had just become aware of this. It was not really pronounced, but more like a fouled plug or something. Sure enough, there was a TSB for this.

Unfortunately, I never discerned if the service performed worked or not as I traded that Avalanche in for the 2013 before the service was finished.

I did drive the 2010 home that night and returned it to the dealer the next morning. I can't say that I noticed the rough idle during the last 20 miles of driving before I picked up the 2013 model. I was in a state of confusion.  Shocked

I don't recall what the work was, but I may still have the service codes for the work they performed. Let me know if you want that information.
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« Reply #5 on: 05/04/13 06:31 AM »

If the engine was designed for AFM, surely GM built the thing with elements that counter side effects with cylinders shutting off, oil flow, cylinder wear,  cooling impact , etc. All auto manufactures have this technology now so won't all car companies be in the same boat? Will we all see these issues with AFM?  Huh
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« Reply #6 on: 05/04/13 12:35 PM »

I don't recall what the work was, but I may still have the service codes for the work they performed. Let me know if you want that information.
I would very much like to know what work was done, relating to the TSB.

Since it's a '10, that might have been early enough for the replacement of the oil pan gasket & the PCV system side valve cover, which is one of the fixes for AFM issues.  The gasket incorporates a shield which minimizes the effect of excessive oil spray from the AFM relief valve, during certain driving conditions.

Another possibility would be the replacement of the throttle position sensor, which was an issue on several model years.  GM established a special extended warranty for this condition.

Please, let us know what you find out.  Thanks!

Nick
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« Reply #7 on: 05/04/13 12:55 PM »

Will we all see these issues with AFM?  Huh
My personal belief is that AFM is a technology that will be difficult to perfect.  Maybe GM, or one of the other auto manufacturers will prove me wrong.

Something EMSDC said caught my eye.  I wouldn't expect to see a lot of AFM activity between 0-35 MPH, in the city.

Any way you look at it, the exhaust note on AFM-equipped 5.3's sound odd to me, even while idling. A co-worker has an '08 Silverado with a 4.8, and no AFM.  That engine sounds exactly like an LS, should.

So, when I finally turn off my AFM, I expect to hear the same odd exhaust note, while idling - since AFM shouldn't be active, then.

Nick
« Last Edit: 05/04/13 05:00 PM by Nick@Night » Logged

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« Reply #8 on: 05/04/13 04:14 PM »

I would very much like to know what work was done, relating to the TSB.

Since it's a '10, that might have been early enough for the replacement of the oil pan gasket & the PCV system side valve cover, which is one of the fixes for AFM issues.  The gasket incorporates a shield which minimizes the effect of excessive oil spray from the AFM relief valve, during certain driving conditions.

Another possibility would be the replacement of the throttle position sensor, which was an issue on several model years.  GM established a special extended warranty for this condition.

Please, let us know what you find out.  Thanks!

Nick

I had some time yesterday to look through the paper work and did not see anything on the work order listing the condition. I'll speak with the service guy in a week or so when I return for paint issues.  Huh

I often drive the last 1/2 mile in my neighborhood with a strict 25 mph limit in cruise control. It has activated as low as 23 mph, but typically 25 mph. If the kid activities are non existent, I'll cycle through the DIC and am surprised how much of this drive is on 4 cylinders and very close to idle rpm. I can feel when it jumps back to 8 either from a slight up hill section or when I'm down to 5 mph nearing a stop.

The engine & transmission on the 13 is so smooth, I rarely detect the change at highway speeds.

Road trip coming up on Tuesday. I'll be paying attention for differences from the 2010.

The rough idle issue only manifested a few days before I released the 2010 for the 2013. I suspected a fouled plug or loose wire.
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« Reply #9 on: 05/04/13 04:26 PM »

It has activated as low as 23 mph, but typically 25 mph.
Road trip coming up on Tuesday. I'll be paying attention for differences from the 2010.
Have heard that tighter engines, with better compression, will activate earlier & remain in V-4 mode, longer.  Mines an '08 with 70K miles.  Probably a little too late to save my 5.3 from the inevitable, but am going to try, by tuning out AFM.

The rough idle issue only manifested a few days before I released the 2010 for the 2013. I suspected a fouled plug or loose wire.
I was interested because the dealer seemed to already know what the issue was.  Thanks for looking into it.

Nick
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« Reply #10 on: 05/04/13 04:31 PM »

Have heard that tighter engines, with better compression, will activate earlier & remain in V-4 mode, longer.  Mines an '08 with 70K miles.  Probably a little too late to save my 5.3 from the inevitable, but am going to try, by tuning out AFM.I was interested because the dealer seemed to already know what the issue was.  Thanks for looking into it.

Nick

I'll press about it. My guy is a very long time friend. I do not recall where I'd heard of this a month or so before, but it was not on this forum.

(Revision/Addition) I'm wondering now if he was speaking out loud as he is aware of my long history with CAFCNA, an Avalanche owner/driver since 03, and I've asked him about 2 other Avalanche drivers CAFCNA members I know of that frequent his new location. He did that when I brought my 2010 Z71 in after the first oil change indicated a rear main seal leak. It was fixed as warranty. This may have been also or they halted this fix when they learned I was about to trade it in for the new one.  Huh

The lowest my 2010 would allow cruise control was 24 mph.

I'd be very happy with engine braking while in cruise on long downhill grades. All of my Avalanches have been like Soap Box Derby vehicles while going downhill.  Shocked
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« Reply #11 on: 05/04/13 04:38 PM »

All of my Avalanches have been like Soap Box Derby vehicles while going downhill.  Shocked
Was thinking that's where the term Wheeeeeeeeeeeeeeeee started.
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« Reply #12 on: 05/04/13 04:46 PM »

Was thinking that's where the term Wheeeeeeeeeeeeeeeee started.

It was more like "Please Stop!" even though my pedal was maxed down as far it would go and my eyes were closed more than a few times. I decided a long time ago I did not want to be a witness to my own demise. The 03 was terrible and the 10 was much improved. The 13 is near perfect but it is still breaking in.

I do a lot of mountain driving, some of it via interstates. The rig is great at 85+ but the state and local authorities are just waiting for my lapse in attention.
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« Reply #13 on: 05/04/13 04:57 PM »

If the engine was designed for AFM, surely GM built the thing with elements that counter side effects with cylinders shutting off, oil flow, cylinder wear,  cooling impact , etc. All auto manufactures have this technology now so won't all car companies be in the same boat? Will we all see these issues with AFM?  Huh

This be what we call naive. Look up 4/6/8 Caddy engines from the mid '80's. As with those motors, the 5.3 wasn't designed for AFM.  It's a late life retrofit. Other manufacturers, notably Honda, are using this successfully. GM ain't Honda.
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« Reply #14 on: 05/04/13 05:05 PM »

This be what we call naive. Look up 4/6/8 Caddy engines from the mid '80's. As with those motors, the 5.3 wasn't designed for AFM.  It's a late life retrofit. Other manufacturers, notably Honda, are using this successfully. GM ain't Honda.

This thought brought up a recollection. Piston Slap

Im not jacking the thread, Honest.

The 03 was doing this from day one and was new to me. I found CAFCNA in July and that was a hot and long discussion. The 2010 had it on occasions as would be expected with cold weather starts or after prolonged resting periods of 5 days or more.

So far with the 2013, I have not detected it. I have only had a few cold weather moments and a few 4+ days between starts. NADA

It doesn't sound like a boat at idle in a marina either.
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« Reply #15 on: 05/04/13 05:30 PM »

5.3 piston slap started with day one of this small block design update back in '99. First GM denied it existed. Then they said it was normal, which it actually was in a twisted way. Then they reinstated their 50's/60's position that 1K mi/qt oil consumption was perfectly ok for new motors. Then they kinda fixed the piston slap problem but not totally. Then when DOD/AFM was implemented they got some relief as all that cold lifter noise was difficult to discern from piston slap. Then the poor AFM design started biting them in the ass by totally dorking up 1 & 7, which they at first completely denied when it began to first show up as simple excessive oil consumption issues. And then.......

And that's just engines. Wanna talk about brakes??? How 'bout transmissions??

GM has been lost to me for at least a decade. The only reason I bought an Av is because no one else makes one.
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« Reply #16 on: 05/04/13 05:39 PM »

Constantly
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« Reply #17 on: 05/04/13 05:45 PM »

And what really makes me so cranky is that it didn't usta be this way. I fell in love with the Chevy small block V8 when it first hit the streets in '55. A great bit of design and design execution. Despite GM's worst efforts wrt the 5.3 revision, it lives to this day.
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« Reply #18 on: 05/04/13 05:54 PM »

And what really makes me so cranky is that it didn't usta be this way. I fell in love with the Chevy small block V8 when it first hit the streets in '55. A great bit of design and design execution.

I agree 90% of the over 40 vehicles I have owned have been GM, I love the styling and interiors, but too many have lived up to the name "Garbage Motors"

I love my Avy and will probably never part with this one, but the AFM has been a huge pain in the posterior!  
I was lucky to have a great service manager and with the help of this site was able to get every possible TSB done while under warranty.

Now I just have to save a few bucks to get a new tuner to disable AFM.
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« Reply #19 on: 05/04/13 06:28 PM »


Now I just have to save a few bucks to get a new tuner to disable AFM.
Which way are you leaning on a tune?

Also, I know GM has made some missteps,  but would you rather have a Triton?
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« Reply #20 on: 05/04/13 06:38 PM »

...  but would you rather have a Triton?

Or a Furd?



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« Reply #21 on: 05/04/13 06:39 PM »

I currently have an Edge CS programmer, but it does not turn off AFM. I want the DiabloSport inTune handheld tuner.
I really don't want to go custom tune as I want to be able to switch between modes and don't wanna have to buy another ECM to tune and then swap it back with the stocker for winter use or economy mode.
I considered doing an all out performance tune on a separate ECM and keep my stock ECM and Edge programmer but that is way too much money for me to justify to the better half... especially when all my extra cash is supposed to be going into the new bike fund!!!
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« Reply #22 on: 05/04/13 07:18 PM »

I really don't want to go custom tune as I want to be able to switch between modes and don't wanna have to buy another ECM to tune and then swap it back with the stocker for winter use or economy mode.
Haven't fallen in love with any of the handhelds.  

Module swapping won't really work for the 6-speed, unless you aren't concerned about the TCM. Figure I'll be in one, someday.

Best solution for me is the AutoCal device, but I'd want a tuner that's willing to pick up the phone.  

I half expected for Nelson to offer AutoCal, but could find no mention of it on his site.  

You know,  I may actually spring for that Range AFM Disable device, and table the tuning for another year.

Nick



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« Reply #23 on: 05/06/13 03:09 PM »

Or a Furd?





Yes, I would...eco boost six. Turbos work great here.
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« Reply #24 on: 05/06/13 07:06 PM »

This be what we call naive. Look up 4/6/8 Caddy engines from the mid '80's. As with those motors, the 5.3 wasn't designed for AFM.  It's a late life retrofit. Other manufacturers, notably Honda, are using this successfully. GM ain't Honda.

C'mon that not quite fair......used to drive my uncle's Caddy....the GM 4/6/8 V8 was a great idea but way before its time and they were the only manufacturer to even try the concept....... Unfortunately it was implemented using electromechanical solenoids controlling the valve lockup powered by an electronic controller of the VIC 20 era with the brainpower of a digital watch. And on a heavy vehicle like a Caddy or Avy, 4 cylinders is good only while coasting and 8 is needed for power........the idea of going through a 6 mode was stupid altogether because you unbalance the engine with 1 cylinder opposing 2 on the power stroke.....on a positive note it did save a little gas in the 8 mpg era but unfortunately in the 80 cents a gallon era you were better off paying for cheap gas than expensive repairs on a kludged engine. Even so, that engine had guts! And Hondas of that era with all their vacuum controllers for emissions, fluky carbs, rusting fenders and engine supports were only trouble free in their owners' minds.

The AFM system using oil pressure to control valve openings powered by sophisticated electronic controllers worked fine and trouble free on my '07, but nonetheless went to '12 & '13 to get one with the valve cover/crankcase baffle mods as a precaution against the problem in the future. Smooth as silk.....can't feel and don't care when or if it switches from 4 to 8.

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« Reply #25 on: 05/07/13 12:15 PM »

I agree 90% of the over 40 vehicles I have owned have been GM, I love the styling and interiors, but too many have lived up to the name "Garbage Motors"

I love my Avy and will probably never part with this one, but the AFM has been a huge pain in the posterior!  
I was lucky to have a great service manager and with the help of this site was able to get every possible TSB done while under warranty.

Now I just have to save a few bucks to get a new tuner to disable AFM.
[/quote

I run my 2013 in M5 all the time, Disables AFM, put tuning it out is the best, but you loose your warranty.
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« Reply #26 on: 05/07/13 03:14 PM »

Of course it's fair......to assume new GM systems are properly thought out prior to production is naive. In addition to 4/6/8, there was the Olds diesel built on the gas small block, the early turbo Buick V6. the early 700R4 tranny...... I'm all for innovation and in all cases it wouldn't have been so bad if GM had made the victims whole. But they didn't. Customers were mostly left holding the bag and beating on the stone wall of denial and whut?
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« Reply #27 on: 05/08/13 06:12 AM »

Of course it's fair......to assume new GM systems are properly thought out prior to production is naive. In addition to 4/6/8, there was the Olds diesel built on the gas small block, the early turbo Buick V6. the early 700R4 tranny...... I'm all for innovation and in all cases it wouldn't have been so bad if GM had made the victims whole. But they didn't. Customers were mostly left holding the bag and beating on the stone wall of denial and whut?

They can and do make great products.....problems arise when they try to cater to a high tech upscale crowds like Olds (which was always the testing grounds before Caddy upgrades) or to meet last minute requirements for Government regulations.The Olds diesel was brought about due in part to the rising cost of gasoline compared to diesel and lack of Government emission requirements for diesel engines. So they took a perfectly good gas engine design and converted it to diesel and without taking the time or effort to design or tool up for strengthening the bottom end to handle the greater loads. The only solution was to retrofit it back as a gas engine which I understand GM did for low mileage vehicles even if out of warranty. If is wasn't for Government mileage requirements there never would have been an AFM.......a 7000 lb vehicle needs a powerful V8....so what's the next solution after dumping AFM?..... go to a V6 for next year's truck line that's kludged up with gimmicks similar to AFM to give better mileage and similar hp on paper, time will judge the merits of this change.

Personally, I hate V6s...had 'em in a Chevy Citation and minivans, a POS.......they are kludged design to fit a 6 cylinder motor transversely into the limited space under a front drive hood. An unbalanced design with bad harmonics that has to be doped up to run as smooth as an inherently balanced V4, V8, or V12. More engineering goes into the design of the motor mounts to shield the vibrational imbalances than into the design of the engine to remove the bad harmonics, e.g. counter rotating balance shafts. The whole concept of 2 cylinders opposing 1 on a power stroke in a 90 degree V8 configurations is not an advance to a truck, probably being done so they could interchange engines from their current smaller FWD/AWD vehicles. The future will show how well they work in truck applications. Large vehicles the size of an Avy/Silverado/Suburban have the space under the hood and would likely be better served with a large I6, mid size V8 or small block V12 configuration.

Given the speed of emerging technologies, ever onerous Government regulations and pressure to make yearly changes to keep market share and attract new buyers, customers will always be left holding the bag because the environment is not conducive to a zero defects design and production......and whether GM or any other automaker, the customer will ultimately always be the one holding the bag for unforseen adverse design changes.
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Current Chevys -   '12 Black LT; '13 Fairway Green LT Z71; '13 Malibu LT
First Avy - '07 Silver Birch LT
Previous  Chevys: '11 Tahoe LT; '11 Malibu LS; '06 Colorado WT; '80 Citation (a FWD POS -turned me off Chevys for 15 years); '75 Impala; 72 Chevelle; '69 Camaro R/T; '65 Impala SS; '62 Nova; '59 Impala; '53 model 210
Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #28 on: 05/08/13 12:52 PM »


So, when I finally turn off my AFM, I expect to hear the same odd exhaust note, while idling - since AFM shouldn't be active, then.

Nick
[/quote]


Now I just have to save a few bucks to get a new tuner to disable AFM.
[/quote]

Just turned AFM off yesterday on my '07 and I seriously feel like a huge weight has been lifted off my back...I've had my avy for about 3 months and noticed oil consumption within the first week, that's when I started researching and found "the club" and also about the design flaws of AFM. Every time I've driven my new truck since then I haven't truly enjoyed it due to the visions in my head of oil splashing and gunk building up in my cylinders. Since yesterday I'm feeling good about buying the truck that I always wanted back before I knew some of the dumb stuff that commonly goes wrong with them. The inTune is a handy little device and I anticipate I'll like it more as I figure out how to tweak it. And just a thought on the range device...$200 for just that seems pointless when a brand new intune can be had for $380 or less. Diablosport even has a $100 credit right now for turning in an old predator. Turn it off fellas, get your peace of mind.
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« Reply #29 on: 05/08/13 03:34 PM »

The inTune is a handy little device and I anticipate I'll like it more as I figure out how to tweak it. And just a thought on the range device...$200 for just that seems pointless when a brand new intune can be had for $380 or less. Diablosport even has a $100 credit right now for turning in an old predator. Turn it off fellas, get your peace of mind.
Appreciate the observations.

Please, keep us up to date with your thoughts about inTune.  The reviews I've read have been a little sketchy, but that doesn't mean someone couldn't change my mind.

Another thing to remember is the Diablo folks have been very late to the game, when it comes to transmission tweaks.  This could be a good thing, or a bad thing.

Good luck!

Nick



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Formerly, "SportRedNick"

2003  Dark Grey Metallic Z-71
2004  Sport Red Metallic  Z-71
2008  Deep Ruby Metallic Z-71

"Would trade them all in for one Bermuda Blue"
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« Reply #30 on: 05/09/13 10:24 AM »

Appreciate the observations.

Please, keep us up to date with your thoughts about inTune.  The reviews I've read have been a little sketchy, but that doesn't mean someone couldn't change my mind.

Another thing to remember is the Diablo folks have been very late to the game, when it comes to transmission tweaks.  This could be a good thing, or a bad thing.

Good luck!

Nick

I am by no means an expert when it come to engines or tuning them and I only have experience with the intune and no other brands or models of tuners. With that being said it was clear to my untrained senses that my truck ran better that night after tuning than it did in the morning before I did it.


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« Reply #31 on: 05/09/13 02:17 PM »

No expert here, either.

Was wondering how easy it is to return the vehicle to stock, using inTune?  Do you wade through menus looking for the parmeters that have been changed, or does it remember the vehicles former state?  Just curious.

Especially with an older vehicle, like mine, I believe a custom tuner would offer something the hand-helds, don't: They usually take a snap-shot of the vehicles current state, before the tune is written.  Among other things, they can find anamolies that should be corrected, before the tune is installed.

Still trying to think it through.  Thanks for the feedback.

Nick
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Formerly, "SportRedNick"

2003  Dark Grey Metallic Z-71
2004  Sport Red Metallic  Z-71
2008  Deep Ruby Metallic Z-71

"Would trade them all in for one Bermuda Blue"
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« Reply #32 on: 05/10/13 10:19 AM »

I haven't removed the tune yet but the user manual shows it being a one step process...I would also like to look into a custom tune someday just for that same reason of the initial check up of the vehicle but I had to have an immediate solution for AFM it was really wearing on me, and with the intune I guess I could data log and have DiabLew or someone write a custom tune and save it on the device...not sure if I'd get that same diagnostic snap shot or not that way though.
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« Reply #33 on: 05/10/13 12:01 PM »

Wearing on me, too.  Time to make a decision.

Thanks for your help!

Nick
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2003  Dark Grey Metallic Z-71
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« Reply #34 on: 05/10/13 03:17 PM »

Wearing on me, too.  Time to make a decision.

Thanks for your help!

Nick

Anytime...alot of your posts are what originally brought this matter to my attention, coupling that with my truck's symptoms I was able to pin point this as my problem and I'm just hoping I saved it since I don't know how well the previous owner took care of it...he obviously didn't monitor TSBs lol
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« Reply #35 on: 05/11/13 05:03 PM »

I have a 2011 Avalanche with 18000 miles and have the rough idle at stops as others have mention (no service codes). The question I have is while driving in city conditions 0-35 mph with stops, when the AFM shifts downs from 8 to 4 the entire ride of the vehicle changes as in not as smooth when using 8 cylinders. It seems like it really struggles while in the 4 cylinders during city driving.

Anybody in the club have the same?   Maybe it's me, but I sure didn't notice it when I bought it new with 5100 miles!

Quoted is the original post on the AFM - oil consumption issue.

Here's my two cents again...actually up to six cents on this issue because it is really bugging me.  After reading many of the posts in this forum on the AFM issue, I traded my cherry fully equipped 2007 for a new 2013 Avalanche, earlier I traded a 2011 Tahoe for a 2012 Avalanche to get more room in the rear seat area. No regrets because I always colored component wanted smoothies anyway. Seems a lot of posters are turning off the AFM feature on older Avys which is probably a wise move to delay or prevent the #1/#7 stuck oil ring/oil consumption issue. That is not an option for me at this time since my vehicles are still under warranty; however since I plan to keep the Avys forever I worry about problems 4-5 years down the road and depending upon future posts and info may have to go that route eventually.

The original post above references a 2011 Avy which may have this issue and I did a little digging to find out just how many years of vehicles may be involved and if the problems were properly identified and eventually solved. I checked out many Chevy Truck and Sierra.Silverado forums and found that there are many posts of TSBs and corporate memos covering the oil consumption/AFM issue. In particular TSB 10-06-011-008 dated 8/24/2010; Bulletin/TSB 10-06-008B dated 3/7/2011 and Corporate Bulleting/Letter to Dealers 0601008G dated 1/3/2013 which is a 2013 issue and the most recent that I could find.  All will be listed below. Of particular note is that the problem is also associated with 2010 - 2011 Avalanches built prior to 2/1/2011 the date of the updated valve cover and 10/2010 the date of the AFM shield. I could find no mention of vehicles affected after the 2/1/2011 build date.

On each board there are numerous posts on the issue....the oil consumption issue seems to focus around two points.....PCV valve....seems that on earlier vehicles there was a problem with the location of the PCV valve pickup in the valve cover......modified valve covers were placed on the earlier 2007/08 vehicles to rectify this problem; however I had seen posts where this had been done and owners checked the line going to the intake manifold after the modification and it was still pulling oil....saw a few other posts that said there was a later modification where the PCV valve was removed altogether and a controlled orifice was installed to reduce oil pull through the intake manifold/valves into the combustion chamber. AFM......Then there were posts on the AFM problem and how oil spray discharged from the AFM valve overloaded and clogged the oil rings on the #1/#7 pistons. The posts referenced the dual problem.....doesn't matter if the oil is pulled through the induction system, burned and clogging the compression rings and/or discharges by the AFM valve and by passing clogged oil control rings to get burned in the combustion chamber.....the result is the same....oil will be burned, plugs will foul and the engine will misfire. If this is the case, shutting down the AFM with a tuner will help, but depending on the year and if PCV system modifications were not made, it may only delay the onset of the problem. Of note in the later correspondence was that multiple oil monitoring was no longer required before addressing the problem in faulty engines.

Also noted that there were many owners with high mileage vehicles who had not yet experienced the problem. There were posts by mechanics who have seen a lot of older Avys who blame the problem on extended oil changes calling GMs OLM (oil life monitor) an engine killer some going 12K+ on the oil changes due to the monitor, and that the problems were more frequent in vehicles that did not use synthetic or exceeded 3K-5K oil/filter changes. Others, like GM attributed the increased frequency to driving styles which I guess would have an effect if the AFM is still active.

One thing I did not see mentioned was engine oil pressure. From the day I bought the '07 new it would routinely start at 55-60 psi and level to about 40 psi at warm idle. I thought that was unusual, but the dealer said it was within normal specs. Of course I didn't believe him and drove a few others in the lot and the '07s and '08s ran the same pressures. When I had purchased the '11 Tahoe (manufactured 4/2011), I noticed that it would start at 40-45  psi and level to 25-30 at warm idle....and that is the pressures where the '12 and '13 Avys also run using the same Mobil 1 5W-30. Perhaps there were other engineering changes in later models to address the AFM problem by reducing pressure in the oil galleries to lower AFM valve discharge pressure and volume of oil spray?HuhHuhHuh?? I wonder if anyone in the forum with high oil consumption are also running at higher pressures with up to 60 psi on startup.

Following are the TSB/Correspondence I ran across:

0601008G:
Engine Oil Consumption on Aluminum
Block/Iron Block Engines with Active  Fuel Management
(AFM) (Install AFM Oil Deflector and Clean Carbon from
Cylinder and/or Install Updated Valve Cover) (Jan 3, 2013)

Subject: Engine Oil Consumption on Aluminum Block/Iron Block Engines with
Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean
Carbon from Cylinder and/or Install Updated Valve Cover)
Models: 2007-2011
Cadillac Escalade Models
2007-2011
Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe
2010-2011
Chevrolet Camaro
2007-2011
GMC Sierra 1500, Sierra Denali, Yukon Models
2008-2009
Pontiac G8 GT
Built Prior to February 1, 2011 (Updated Valve Cover) and October 2010 (AFM Shield)
Equipped with Any of the Following Engines:
– Aluminum Block V8  Engine with Active Fuel Management (AFM) (RPOs L94, LZ1,
L99, LC9, LH6, L76, LFA, L92)
– Iron Block V8 Engine with Active Fuel Management (AFM) (RPOs LMG, LY5)
– Hybrid Engine (RPO LFA – Only Applies to Hybrid Models Built July 7, 2009 February 1, 2011 – Prior Builds Not Cast For AFM Valve)
Attention: This bulletin does not apply to the Buick Rainier, Chevrolet TrailBlazer and
GMC Envoy equipped with LH6 due to a different design oil pan and AFM pressure relief valve.
This bulletin is being revised to update the Warranty Information. Please discard Corporate
Bulletin Number 100601008F

(Section 06 – Engine/Propulsion System).

Condition
Some customers may comment about engine oil consumption of vehicles  with higher mileage
(approximately 48,000 to 64,000 km (30,000 to 40,000 mi) and a service engine soon light being on
and/or rough running engine. Verify that the PCV system is functioning properly. If the customer
understands that some oil consumption is normal and still feels the consumption level is excessive, more than 1 quart per 2000 to 3000 miles of driving, perform the service indicated in this bulletin. It is no longer necessary to have the customer return multiple times to have the usage verified.

Cause
This condition may be caused by two conditions. Oil pulled through the PCV system or oil spray that
is discharged from the AFM pressure relief valve within the crankcase. Under most driving
conditions and drive cycles, the discharged oil does not cause a problem. Under certain drive cycles
(extended high engine speed operation), in combination with parts at the high end of their tolerance specification, the oil spray quantity may be more than usual, resulting in excessive deposit
formation in the piston ring grooves, causing increased oil consumption and cracked or fouled spark
plugs (#1 and/or #7). Refer to the latest version of Corporate Bulletin Number 120601001.
<
<
<gap
<
<
If this repair does not correct the condition, it may be necessary to replace all of the piston
assemblies (piston and rings) with new parts. Refer to SI for repair procedure.


------------------------------------------------------------------------------

Bulletin No.: 10-06-01-008B
Date: March 07, 2011

Subject: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder)

Models:  2007-2009 Cadillac Escalade, Escalade ESV, Escalade EXT 2007-2009 Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe 2007-2009 GMC Sierra 1500, Sierra Denali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL  2008-2009 Pontiac G8 GT  Equipped with Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs LC9, LH6, L76, LFA, L92) with Greater than 45,000 km (28,000 mi)

Supercede: This bulletin is being revised to add the 2009 model year and new Correction information for the 2009 model year - left rocker arm cover replacement. Information has also been added after step 9. Please discard Corporate Bulletin Number 10-06-01-008A (Section 06 - Engine/Propulsion System).

Condition

Some customers may comment about engine oil consumption of vehicles with higher mileage (approximately 48,000 to 64,000 km (30,000 to 40,000 mi). Verify that the induction system is assembled correctly and that there is no evidence that the engine has been ingesting dirty air due to a mis-assembled induction system. Also verify that the PCV system is functioning properly. If diagnostic procedures indicate that oil consumption is piston/piston ring related, verify that oil consumption is less than 3,000 km (2,000 mi) per liter/quart. If these conditions are met and oil consumption is less than 3,000 km (2,000 mi) per liter/quart, perform the service indicated in this bulletin.

Cause

This condition may be caused by oil spray that is discharged from the AFM pressure relief valve within the crankcase. Under most driving conditions and drive cycles, the discharged oil does not cause a problem. Under certain drive cycles (extended high engine speed operation), in combination with parts at the high end of their tolerance specification, the oil spray quantity may be more than usual, resulting in excessive deposit formation in the piston ring grooves, causing increased oil consumption.

Correction 

2009 Vehicles Only

Important  This left rocker arm cover is NOT to be used on 2007-2008 vehicles because of the calibration of the PCV orifice being different in 2007-2008.

A new left rocker arm cover has been released for 2009 engines. Technicians should replace the left rocker arm cover with GM P/N 12642655. This rocker arm cover has relocated PCV drain holes that prevents PCV pullover into the intake manifold. Refer to SI for Valve Rocker Arm Cover Replacement - Left Side.

2008-2007 Vehicles Only

To correct this condition, perform the piston cleaning procedure as described in this document, and install a shield over the AFM pressure relief valve per the procedure outlined in this document. Monitor oil consumption after this repair to ensure oil consumption has improved to acceptable levels. If this repair does not correct the condition, it may be necessary to replace the piston assemblies (piston and rings) with new parts.

Important  It is critical in this cleaning process that the engine/fuel injector cleaner remain in the cylinders for a minimum of 2.5 hours to fully clean the components. The cleaner solution must be removed before a maximum of three hours.

1. Verify the oil consumption concern following Corporate Bulletin Number 01-06-01-011F. If oil consumption is found, continue on with this bulletin.

2. Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).

3. Clean the pistons by putting 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861802 (in Canada, use 88861804), in each cylinder. Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours and then remove the cleaner. A suggested method of removing the cleaner is cranking engine over. Make sure to unplug the ignition coils and fuel injector before cranking the engine over. Also make sure that the painted surfaces are covered so no damage is done.

4. Remove the oil pan. Refer to Oil Pan Replacement in SI.

5. Remove the AFM valve.

6. Install the new shield, GM P/N 12639759, and tighten the AFM valve to the oil pan to 28 Nm (20 lb ft).

Important  Ensure that the engine cleaner is thoroughly removed before reinstalling the spark plugs. Failure to do so may result in a hydro-lock condition.

7. Reinstall the spark plugs. Replace the spark plugs if necessary due to full of carbon.

8. Reinstall the oil pan. Refer to the Oil Pan Installation procedure in SI. Replace the oil pan gasket if necessary. Refer to the parts catalog. Replace the engine oil if necessary.

9. Re-evaluate the oil consumption. Document on the repair order. If the oil consumption is still greater than 0.946 L (1 qt) in 3,200 km (2000 mi), replacement of the pistons and rings will be required.

Important  Some minor scratches may be noticed on the cylinder walls during piston and ring replacement. If the scratch cannot be felt when running your finger nail over it, the scratch is considered normal wear and the block or engine should not be replaced.


----------------------------------------------------------------------------------

TSB #10-06-01-008:
Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder) - (Aug 24, 2010)


Subject: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder)


Models: 2007-2008 Cadillac Escalade, Escalade ESV, Escalade EXT

2007-2008 Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe

2007-2008 GMC Sierra 1500, Sierra Denali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL

2008 Pontiac G8 GT

Equipped with Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs LC9, LH6, L76, LFA, L92)

with Greater than 45,000 km (28,000 mi)




--------------------------------------------------------------------------------

Condition
Some customers may comment about engine oil consumption on vehicles with 45,000-56,000 km (28,000-35,000 mi) or greater. Upon further investigation, a technician may find that the engine uses 0.946 L (1 qt) of oil in as little as 1,200 km (800 mi). After this bulletin is completed, the vehicle should be driven 3,200-4,800 km (2,000-3,000 mi), then tested for oil consumption again.

Cause
This condition may be caused by an uncovered AFM valve that sprays oil on the bottom of the cylinders when the vehicle is in four cylinder mode. Over time, the rings cannot handle the volume and begin to stick with carbon. At that point, the vehicle oil usage may go up considerably.

Correction
A new AFM shield/ring cleaning process has been developed to restore the function of the rings. If the oil economy has not improved to no more than 0.946 L (1 qt) of oil consumed in 3200 km (2000 mi) after cleaning, it may be necessary to replace all of the pistons and piston rings.
Oh and I almost forgot, here is a copy of an email from GM to their dealers as GM tech document released April 28th 2011, describing the same symptoms showing different solutions than the attachment above.
All seem to be related to the PCV valve. This latest document describes a new and improved PCV valve which requires valve cover modifications to support the newly designed PCV valve but as I've stated, the information is a couple of years old.
#PIP4574M: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Investigation Update

Subject: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Investigation Update

Models: 2007 Buick Rainier

2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe, Trail Blazer
2007-2008 GMC Envoy, Sierra, Yukon
2008 Pontiac G8
2007-2008 Saab 97x
with a 5.3L or 6.0L Aluminum Block V8 Engine
and AFM (Active Fuel Management)
RPOs LC9, LH6, L76, or LFA


--------------------------------------------------------------------------------

This PI was superseded to include revise the affected RPO codes, specify that this is for Aluminum Block Engines only, update models and provide a general update on the status of this investigation in step 5. Please discard PIP4574M.

--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may complain that their vehicle has been using approximately 1 quart of oil every 500-1,000 miles. In most cases, the customer will advise that this did not start until the engine accumulated approximately 30,000 miles or more. In some cases, the customer may note that this is more apparent when driving at highway speed. In rare instances, a SES light and engine misfire may be encountered with a P0300 DTC.

Upon inspection, an oil fouled spark plug(s) may be noted. In most cases, static compression and cylinder leakage testing will appear normal. Excessive oil may or may not be found in the intake manifold.

In most cases, this is the result of stuck oil control rings. Generally, the stuck oil control rings are the result of excessive oil on the cylinder walls. The excessive oil can come from the PCV system and/or the AFM pressure relief valve in the oil pan.

Recommendation/Instructions:
If this concern is encountered, follow the steps below:

Visually inspect the entire engine and the underside of the vehicle for any evidence of oil leaks and repair them as necessary.
Inspect the fresh air hose/pipe that is attached to the RF (passenger side) valve cover and all related connections for restrictions, such as plastic casting flash or a pinched hose, and repair as necessary. A restriction in this area may cause excessive crankcase vacuum and oil consumption through the PCV vacuum tube.
If the truck has an engine misfire and a spark plug that is obviously oil fouled, skip to step 4 since this proves that it has an obvious oil consumption concern. If not, perform an oil consumption test as outlined in the latest version of oil consumption of 01-06-01-011 to verify the concern before proceeding to step 4. Allow the vehicle to sit on a level surface with the engine off for at least 10 minutes to allow the entire engine to drain back to the oil pan before checking the engine oil level and adding oil. Compare the oil consumption test results to one of the scenarios below to determine further direction:
• If oil consumption is Less than 1 quart of oil every 2,000 miles and no low oil light has been experienced, no repairs should be performed as this should be considered acceptable oil consumption as outlined in the latest version of 01-06-01-011.

• If oil consumption is Less than 1 quart of oil every 2,000 miles but the customer has experienced a low oil light, refer to the latest version of PIP3959 for a potential low oil light sensor concern.

• If the dealership verifies that oil consumption is More than 1 quart every 2,000 miles, perform the steps below as necessary:

Determine if the engine has been ingesting oil through the PCV system by removing the intake manifold and measuring how much oil can be poured out of the throttle body opening with the throttle body removed. It is normal to get a couple of teaspoons of oil out of the intake. If the engine has been ingesting oil through the PCV system, several ounces of oil will be measured, many times as much as a 1/4-1/2 quart.
• If the engine HAS NOT been ingesting oil through the PCV system, go to step 5.

• If the engine HAS been ingesting oil through the PCV system, inspect the PCV baffle as outlined in the rest of Step 4 below:

4a. Remove the LH (driver's side) valve cover and inspect the PCV baffle drain holes shown below to see if they are plugged with hardened oil deposits. If they are plugged, replace the valve cover, ensure that the customer is changing their oil according to the maintenance schedule in their owner's manual, and re-evaluate the concern. Generally, this would not be a concern until several thousand miles have accumulated.

4b. With the LH (driver's side) valve cover removed, inspect the PCV baffle to ensure that it is properly sealed to the valve cover by flipping it over and adding a little oil to the corner of the valve cover as shown below. The oil should stay in place as shown on the 2 outer valve covers below. If the oil drains into the PCV baffle as pointed out on the middle valve cover below, replace the valve cover. Generally, if this is the cause of the concern, it would have been present early in the life of the vehicle or shortly after valve cover replacement.


Important: If Step 4a or 4b led to valve cover replacement, perform Step 4b again on the replacement valve cover before installing it.


• 4c. If the engine HAS been ingesting oil through the PCV system but the valve cover passed the tests outlined above, the engine may have an over-aggressive lifter that is causing the oil ingestion through the PCV system. Sometimes the lifter may be doing this intermittently so it is not always possible to isolate one by inspecting the lifter flow with the driver's valve cover removed. As a result, it is suggested to replace all 8 of the left/driver bank lifters due to the oil in the intake and re-evaluate the oil consumption concern. The right/passenger side lifters should not cause oil in the intake so there is no need to replace them. If the vehicle returns with excessive oil consumption but is no longer ingesting oil through the PCV system, it most likely has stuck oil control rings as outlined in Step 5.

If the engine HAS NOT been ingesting oil through the PCV system and there are no obvious valve seal concerns, this is most likely the result of the AFM pressure relief valve in the oil pan spraying oil on the bottom of the cylinders when active fuel management is on. This may eventually cause the oil control rings to stick and increase the rate of oil consumption. As outlined in the July 2010 GM STC Service Know-How Emerging Issues Seminar (10210.07D), a related bulletin is going to be released to repair this by cleaning the oil control rings and installing a shield over the AFM pressure relief valve. This bulletin was scheduled for a July 2010 release but the bulletin is still going through the final stages of the release process. At this time, it is on track for a mid-August release date. Once released, you will be able to find the new bulletin in the New Bulletins Section of Service Information and this PI will be updated to include the bulletin number as well.
If you would like to view the July 2010 GM STC Service Know-How Emerging Issues Seminar (10210.07D) mentioned above, you can find it by following this path:

• Go to the GM Training Website. (If necessary, there is a link to this website at GM Global Connect "Dealerworld")

• Enter your Training Person ID and Password.

• Click the "Service Know-How/TECHAssist" Link

• Click the "Emerging Issues" Link



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Current Chevys -   '12 Black LT; '13 Fairway Green LT Z71; '13 Malibu LT
First Avy - '07 Silver Birch LT
Previous  Chevys: '11 Tahoe LT; '11 Malibu LS; '06 Colorado WT; '80 Citation (a FWD POS -turned me off Chevys for 15 years); '75 Impala; 72 Chevelle; '69 Camaro R/T; '65 Impala SS; '62 Nova; '59 Impala; '53 model 210
Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #36 on: 05/11/13 05:08 PM »

Started to read this but my eyes glazed over. Way too much most likely/certainly rehash to screw with for a Mother's Day weekend.
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« Reply #37 on: 05/11/13 05:42 PM »

Thomcat:

My eyes are still open.  A very clear, concise, and smooth(ie) summation.

Happy Mother's Day!

Nick
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« Reply #38 on: 05/15/13 08:20 AM »

One thing I did not see mentioned was engine oil pressure. From the day I bought the '07 new it would routinely start at 55-60 psi and level to about 40 psi at warm idle.

No excessive consumption, yet, but have verified my '08 runs at the higher pressures.  I, too, would like to know what was changed in the last few years of the GMT-900.  Only thing I'm pretty sure about is the new lifter design.

Wonder if we'll ever be lucky enough to see some photos of the valve cover engineering changes?

Nick

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« Reply #39 on: 05/15/13 09:31 AM »

No excessive consumption, yet, but have verified my '08 runs at the higher pressures.  I, too, would like to know what was changed in the last few years of the GMT-900.  Only thing I'm pretty sure about is the new lifter design.

Wonder if we'll ever be lucky enough to see some photos of the valve cover engineering changes?

Nick



What is considered higher pressures? I am running between 50-55
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« Reply #40 on: 05/15/13 10:02 AM »

Once warmed to 210F the '12 and '13 run at 35-40 psi with Mobil 1 5W-30.....idles around 30........max at 65 mph around 2000 rpm at 40 psi (mid gauge)....in the '07 I always felt uncomfortable seeing the voltmeter and temp gauges around 12 o'clock and the oil pressure gauge at 1 to 2 o'clock.

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Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #41 on: 05/15/13 10:09 AM »

Yeah that's about where my '07 is at 1-2 o'clock and I'm running mobil 1 5-30 with AFM off.
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« Reply #42 on: 05/15/13 10:50 AM »

Could be they redesigned the lifters on later models to operate at a lower pressure and a lower set pressure needed to trigger the AFM dump valve to reduce the volume of spray in conjunction with the oil baffle fix in the lower end.

Even if operating with higher pressures.........no AFM,  no oil spray......if I still had my '07 out of warranty......I'd shut it off, even IF it did save gas.
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Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #43 on: 05/15/13 12:02 PM »

Could be they redesigned the lifters on later models to operate at a lower pressure and a lower set pressure needed to trigger the AFM dump valve to reduce the volume of spray in conjunction with the oil baffle fix in the lower end.

Recall the re-designed lifter was one of the AFM fixes for the early GMT-900's.  Would be interesting to see whether the part numbers for the early re-design matched the part numbers for the later numbers.

What accounts for the lower pressures in the later models is the million dollar question, for me.

Nick
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« Reply #44 on: 05/15/13 12:43 PM »

Probably the same oil pump, just set the pressure relief valve on the pump to a lower setting change spring on pump if not adjustable.....even so they would likely change the part number.
I remember reading in the '07 shop manual that the AFM system needed minimum 35-40 psi to operate......they could have changed the AFM valve and everything associated with it to operate at a lower pressure. Anything above 20 psi should be fine to lube the engine.
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« Reply #45 on: 05/15/13 11:55 PM »

Anything above 20 psi should be fine to lube the engine.

You made the point about the different oil pressures, before.  Didn't make an impression, at the time; however, I wouldn't be surprised if the higher oil pressures contributed to the AFM issues.

Eventually, everything we ever wanted to know about GM's AFM initiative will leak out.  (No pun, intended.)

Wonder how old I'll be, by then?

Nick
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« Reply #46 on: 05/16/13 01:00 PM »

You made the point about the different oil pressures, before.  Didn't make an impression, at the time; however, I wouldn't be surprised if the higher oil pressures contributed to the AFM issues.

Eventually, everything we ever wanted to know about GM's AFM initiative will leak out.  (No pun, intended.)

Wonder how old I'll be, by then?

Nick


There definitely seems to be a redesign related to reduced oil pressure. Checked out other Chevy truck forums, e,g, gm-trucks,com, and they seem to experience with lower pressure posts on later Silverados............2011s and later..........warm idle at around 25 psi which climbs to a shade over 40-45 psi at 2000 rpm....exactly what my mine are doing once warmed.
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Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #47 on: 05/25/13 06:49 PM »

Just a note, my 2011 sits at 20psi at idle. Maybe gets to 30 or 35 psi at highway, never 40psi. Worries me a little. Have a slight tick, so i use Lucas upper cylinder lube which helps the tick issue.
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« Reply #48 on: 05/26/13 04:54 AM »

Just a note, my 2011 sits at 20psi at idle. Maybe gets to 30 or 35 psi at highway, never 40psi. Worries me a little. Have a slight tick, so i use Lucas upper cylinder lube which helps the tick issue.


From what I have read the rule of thumb on modern engines is minimum 10 psi per 1000 rpm, so 20 psi at idle (600 rpm) and 38 at 65 mph (2000 rpm) is more than enough and I don't worry anymore....at least for as long as the warranty period.
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Other: '80 Cordoba, '84 Crown Vic, '88 Crown Vic, '90 Fleetwood, '96 Taurus, '99 Cirrus, '00 Explorer, '02 300M, '04 300M, '06 T&C minivan
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« Reply #49 on: 05/26/13 02:10 PM »

No doubt lower oil pressure would ease the problems with the AFM system. I always thought the pressure on these trucks was high anyway. Considered it odd/concerning 'til I found out 55/60 was design normal. Most street vehicles I'd driven up until then, at least those with gauges, relieved at around 40 psi. I've always considered high oil pressure to be a bad thing.
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« Reply #50 on: 05/28/13 06:01 PM »

Good feedback. Thanks for the information.
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« Reply #51 on: 06/06/13 04:27 AM »

Just to chime in here on this issue.

I've been having problems with my 08 Z71 for about a year with the AFM. It's been to my service dealer 4 times to fix a "missfire" where the SES light comes on and I get the "service stabilitrack system" message. I've gotten a lot of great info off of this forum from reading everyone else's issues and remedies. Thanks to you all for that.

First time I had the issue was at ~87k miles in January of 2012. They replaced lifters under warranty as seems to be normal with this issue as an attempt to fix the problem. My truck now has ~114k miles on it. I had the error come up again on 6/15 and just heard from GM yesterday that they will not be replacing the same parts which were determined to need replaced again under the warranty.

I must say that having an Avalanche be my dream vehicle for many years, to finally get one in late 2011 and to have this problem for the majority of the time owning the vehicle, and for GM to tell me I'm out of luck is disappointing to say the least. I'm debating today on what to do with my truck, trade it in on something else, replace the engine or what.

At this point I can say that I'll probably never buy another GM product again, after owning mostly GM products for most of my driving life.
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