AFM and Oil burning opinions

I just read a post on the 2007+ Avys which burn oil.  Please post your experience.  I have a 2007 with 20,000 miles on it.  Just wondering if I should be doing anything to nip this potential problem in the bud.

Turn off AFM (Active Fuel Management)!

Been keeping detailed records on my truck. I started burning 1qt every ~2000 miles around 55k. Disabled AFM at 123,120 (Dec 5, 2012) and started burning only 1qt every ~3000 miles. Did an oil change back at 133,340 miles (done in Sept 2013) and have gone more than 4000 miles since then and still haven't been warned that my oil level is low. Last I checked my oil level looked good on the stick (that was at 135,587 on Dec 12, 2013). Patiently watching to see if my trucks oil consumptions continues to reduce and/or see how long this keeps up. It's probably the cold weather that's behind the reduced consumption but we'll see...

X2, I loose about 1/2 at 6000. I don't drive it much anymore so can't say if that would get worse. 180000 mile on a 2008. I had the diverted and rings but never had the the new valve cover with the PCV.

Thanks...keep them coming.  Now going to read the threads on best way to disable AFM.

So it looks like there are 2 options to disable AFM or is there another?

1. Engine tuner
2. Range technology plug into OBD connector

Pros and cons?

Mine's tuned, but if all you want is to disable AFM the simplest and cheapest way to deal with it is Range Technolorgy

112000+ on my 08, cast iron block oil pressure around 20psi on the gauge at idol, run Amsoil full synth and have no oil burning at all.

Blackcomb said:

oil pressure around 20psi on the gauge at idol

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Interesting... mine sits at 40psi at idle and jumps to 60 under power.

ca2kjet said:

Interesting... mine sits at 40psi at idle and jumps to 60 under power.

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I jump to 40 under power, I also noticed, during the summer the cold start PSI is 20, but during this winter with actual temps in the teens the startup PSI was at 40, but as soon as the truck starts to warm up it goes back to the 20PSI or slightly above that.

Blackcomb said:

I jump to 40 under power, I also noticed, during the summer the cold start PSI is 20, but during this winter with actual temps in the teens the startup PSI was at 40, but as soon as the truck starts to warm up it goes back to the 20PSI or slightly above that.

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That's the way my '12 and '13 operate also.......but my '07 operated 40 psi at idle and 60 at highway speeds.....all used Mobil 1. The article below explains that the iron block engines use a different oil pump than the aluminum blocks (and I'll bet that pump is one of the mods in the in the '12 and' 13 which operate at the same pressures as the iron blocks) and as explained in the article the lower oil pressures delay opening of the AFM valve until the vehicle has reached speed under power.

The document in the link below looks like the definitive GM article on evaluation and correction of the oil consumption problem and AFM and valve cover PCV intake issues identified as the causes...most detailed one I've seen to date.........seems mods were incorporated at different times in the aluminum and iron block 5.3 AFMs. Article details the affected engines by date. Photos show before and after views of the mods, including the modified cover with intake clear of oil splatter and  the AFM shield which directs exhaust downward into the sump through a single hole instead of through the additional 4 side spray holes.....just a guess, but could be a reason why oil pressures are lower in later modified engines. Can't attach the .pdf but I'll list the web address below..   also, article contains many mechanics instructional notes relative to valve seal and cylinder wall inspection results.....


http://img.gogmpartswest.com/pdfs/Oil%20consumption.pdf

Thomcat said:

Can't attach the .pdf but I'll list the web address below..   also, article contains many mechanics instructional notes relative to valve seal and cylinder wall inspection results.....


http://img.gogmpartswest.com/pdfs/Oil%20consumption.pdf

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Thanks!  I am guessing you are a GM tech or know one.  When I worked for GM these SB would come out weekly!  From the looks of it, the  reliability and engineering has improved.  That's not to say they are anywhere close to Japanese quality standards.

Linescreamer said:

I just read a post on the 2007+ Avys which burn oil.  Please post your experience.  I have a 2007 with 20,000 miles on it.  Just wondering if I should be doing anything to nip this potential problem in the bud.

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I had traded my '07 (which didn't burn any oil at 41K) for the '13 in a small part at that time because of all the oil consumption posts and fear of an unmodified '07 engine going bad out of warranty. When the vehicle was almost out of warranty I asked the service manager if they would prophylactically do the valve cover and AFM baffle mod to prevent a future problem after the warranty expires. He said no, but since the vehicle has real low mileage and was in top condition with 3K oil/filter changes and a known history since the vehicle was new, they had the ability under those circumstances to contact Chevrolet and make an exception for an out of warranty repair should I need it in the future. He had advised against trading for that reason alone since of all the Avys the dealership sold, only one developed the problem and that engine had obvious signs of a hard life and abuse, others continue routine servicing at higher mileages with no apparent oil consumption problems.

In the end my primary reason for the trade was to get the 6 spd manual, new Nav system and other features, and not for AFM alone. But, if I decided to keep the '07 I would have turned off the AFM using the Range Tech plug in device before the problem developed and ring damage developed. I had already purchased one and confirmed that it works well and is easily reversible and does not leave a footprint in the ECM ...I keep it in reserve should later experience show that the post 2/11 vehicles with all the mods start to develop AFM oil consumption problems.

2007 with 101,000+ miles on it, was burning a few quarts between changes with the occasional dash warning to top up oil. Bought an intune diablo tuner and disabled the AFM (DOD on the diablo) and it hardly loses / uses any. Huge difference in consumption with minimal mpg change. Well worth it, plus i got a nice little peppy tune to boot! ;o)

I turned off DOD and it did not fix my issue. I replaced the driver side valve cover and they problem went away

My 08 was drinking a quart every thousand miles. Took it to the dealer under drive train warranty. They monitored consumption every 1,000 miles, for 3k miles, then replaced valve cover and put a deflector in for the AFM. Consumption went to 1 qt every 1,200 miles. Monitored again for 3k at 1k mile intervals - then they had the truck for almost 2 weeks. Rebuilt engine with new pistons, rings, and a laundry list of anything they found to be worn or problematic. Next they gave me a 1 year 12k mile extra warranty - since I was now up to around 90k miles. I am now at 116k miles and it does not use a drop of oil between oil changes.

Copy/Paste (mostly) from a similar question:

I had minor oil consumption (1qt @ 5k miles) and decided to disable the AFM with the Range OBD option.

The issue with consumption due to AFM issues is that you need to prevent it before it becomes a problem.  The 4 deactivated cylinders continue to get worse and worse due to many issues that I won't completely outline here, but it has to do with non-combustion in the chambers allowing oil to seep up the cylinder.  Once ruins the rings, you are done...

As I understood from my reading, you need to correct this problem before it happens.  Again, fixing really isn't an issue.  The modified baffle helps if you don't already have ruined ring, but can't fix ruined rings obviously.

Anyway, Range OBD was installed and no oil consumption.  I am at 151k miles and hardly an issue overall.

(Edited Cover to read baffle and readability)