Home Resources Forums Nationals Meets Store
08/29/14 03:14 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Welcome to the Chevy Avalanche Fan Club of North America

Become a Supporting Member

Visit the CAFCNA General Store

 
   Home   Help Search Login Register Bookmark  
Advertisement
Put your advertisement image here...


Advertisement
 
Pages: [1]   Go Down
  Print  
Author Topic: Worse gas mileage with Predator  (Read 1380 times)
0 Members and 1 Guest are viewing this topic.
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« on: 01/03/12 07:06 PM »

Just got a Predator for Christmas, installed the 87 tune and noticed that I have lost 2-3 mpg according to the computer.  Just wondering if anyone else has seen this with their installs?
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
old-chevy-dude
Full Member
****
Offline Offline

Posts: 854


Awards
« Reply #1 on: 01/03/12 07:17 PM »

did you set your tire size?

the predator has a default size in it, something like 205/75 R15..

When you write the tune to the vehicle if you fail to adjust from the default size (even if you have OEM size tires) it tells the ECU you have a different size tire and screws up the speedo and the mpg reading in the vehicle DIC

Logged
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #2 on: 01/03/12 08:37 PM »

I would think that would be in the instructions!
I just got my truck back with new pistons and rings. Gas mileage took a dive, 15 down from 17. I have an app that shows fuel trims short and long. The longs were at +7 and it look like shorts where hovering around +3. The shorts are kind of hard to read as the changed rapidly. All 3 different tunes available had the same results.
Trip before I had the pistons changed long trim was at a -4 and that was after drive quite a while with +4 for a while.
Logged

2008 Z71
ohiobellboy
CAFCNA 2008 Supporting Member
Full Member
*
*
Offline Offline

Posts: 7,102


2 Eagles


Awards
« Reply #3 on: 01/04/12 05:47 AM »

I would think that would be in the instructions!
I just got my truck back with new pistons and rings. Gas mileage took a dive, 15 down from 17. I have an app that shows fuel trims short and long. The longs were at +7 and it look like shorts where hovering around +3. The shorts are kind of hard to read as the changed rapidly. All 3 different tunes available had the same results.
Trip before I had the pistons changed long trim was at a -4 and that was after drive quite a while with +4 for a while.
-4 is too low! Check the Pred forums. Ideal is 0 to -2. If you're at +7 then it needs adjusted. Make sure you're following the proper methods for determining your LTFs. Monte is better at explaining this than I am but I know those are the numbers you're looking for.
Logged

Avy #1 - '04 Z71 Cladded (dark blue metallic) Purchased 9/07 with way too many mods to list. Current mileage 169,*** Nice weather only now.
Avy #2 - '05 Z71 WBH (Bermuda Blue) Twiggy purchased 11/11 Current mileage 151,*** Now used as my winter beater
Avy #3 - '05 Z71 Cladded (Bermuda Blue) Purchased 9/12 as a daily driver for Twiggy. A few mods. Current mileage is 142,***
Other Summer toy - 2011 FLTRUSE (Slate/Black) also called a CVO Road Glide Ultra (Only made one year) Lots of fun on two wheels!
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« Reply #4 on: 01/05/12 05:50 PM »

I thought I changed the tires but maybe it didnt take... I will have to run out and check.  Have been reading on the other forums and trying to figgure that stuff out is like another language for me, just cant wrap my head around the numbers.
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« Reply #5 on: 01/05/12 06:33 PM »

Checked and do have the current tire size in the program.  it should be entered just as the tire shows right? 265/70/r17.  My spedo is also off by 4 mph but cannot seem to change it with the stock tires size entered.
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
ohiobellboy
CAFCNA 2008 Supporting Member
Full Member
*
*
Offline Offline

Posts: 7,102


2 Eagles


Awards
« Reply #6 on: 01/05/12 06:46 PM »

Checked and do have the current tire size in the program.  it should be entered just as the tire shows right? 265/70/r17.  My spedo is also off by 4 mph but cannot seem to change it with the stock tires size entered.
If your speedo is off, then that will account for some of your mileage. Is the speedo fast or slow?
Logged

Avy #1 - '04 Z71 Cladded (dark blue metallic) Purchased 9/07 with way too many mods to list. Current mileage 169,*** Nice weather only now.
Avy #2 - '05 Z71 WBH (Bermuda Blue) Twiggy purchased 11/11 Current mileage 151,*** Now used as my winter beater
Avy #3 - '05 Z71 Cladded (Bermuda Blue) Purchased 9/12 as a daily driver for Twiggy. A few mods. Current mileage is 142,***
Other Summer toy - 2011 FLTRUSE (Slate/Black) also called a CVO Road Glide Ultra (Only made one year) Lots of fun on two wheels!
CodeBlueEMT
CAFCNA 2007 Supporting Member
Full Member
*
*
Offline Offline

Posts: 1,936


Awards
« Reply #7 on: 01/05/12 06:54 PM »

 My fuel mileage can vary 2-3 mpg just from city driving, stop and go vs. setting the cruise on the highway and rolling.

 Did you change any parameters other than trying to enter your correct tire size?

 I didn't try to compute my mpg's right after installing the Predator performance tune. Initially, my right foot tripled in weight.

 Might not hurt to check your air pressures if you haven't done so recently. Every little bit helps.

 Good luck.
Logged
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« Reply #8 on: 01/05/12 08:42 PM »

Speedo reads 60 and gps shows 56.  Before the tune instant mpg on a flat road would vary between 19-21 and after it is 17-18 on the same road with same speed. I haven't changed any other perameters as I don't know what to change
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #9 on: 01/05/12 10:27 PM »

Speedo reads 60 and gps shows 56.  Before the tune instant mpg on a flat road would vary between 19-21 and after it is 17-18 on the same road with same speed. I haven't changed any other perameters as I don't know what to change

Same gas?
Not meaning to  Thread hijacked!
My issue may have been my wheel bearing and maybe the gas, and highway traveled. I tend to get worse mileage on 55. I traveled back 67 (maybe 5 mph slower) DIC showed 19.5 actually 17.9 mpg. I still would have to say not what I expected. Next week highway 44 and 70 (usually my best mpg).
Logged

2008 Z71
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« Reply #10 on: 01/07/12 04:16 PM »

Well I fixed the speedo problem. I adjusted the tire size by tire height in inches. But now my remote start won't work. Seems to be one thi g after the other with this
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #11 on: 01/07/12 08:09 PM »

After reading your post I tried mine, it still works. Maybe coincidence.
Logged

2008 Z71
MightyMouse
Full Member
****
Offline Offline

Posts: 607



Awards
« Reply #12 on: 01/12/12 01:55 PM »

Speedo reads 60 and gps shows 56.  Before the tune instant mpg on a flat road would vary between 19-21 and after it is 17-18 on the same road with same speed. I haven't changed any other perameters as I don't know what to change

If you're logging a +7 LTFT (Long Term Fuel Trim), that means you're running extremely lean, so the drop in mpg makes sense. Keep in mind that weather has a lot to do with LTFTs as the air gets more dense in colder temps, using less fuel.
If you've been running your tune for more than 100 miles and you're still showing +7 (using the Predator's data logging feature), go into the tune and adjust the injector slope by -7. Run it for 50-100 miles and log it again. You should be near zero in your LTFT.

Read the stickys on the diablosport forum as well. They'll help you a lot!

Good luck,
MM
Logged

'07 Dark Blue Metallic LTZ 4X4, Custom dual exhaust, Injen PowerFlow CAI, Sunroof, Chrome door handles, grill, and mirrors, Ambers, Molded mud flaps, Color-matched GM bug deflector, DiabLEW Predator tune, Billet front & rear bowties, Chrome tailgate handle, Chrome side molding, 22x9.5 Liquid Metal Magma's wrapped in GY Fortera SL 305/40R22 rubber
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #13 on: 01/12/12 05:43 PM »

I have read some of them but I think I would be afraid to adjust the settings. I am not sure what happened on that trip. I ran 18.5 down to springfield mo and 18.5 back but haven't filled the tank to verify. The app I have now shows +4, I would have thought that would be on the rich side. I am running the 87mpg boost currently.
« Last Edit: 03/29/12 09:14 PM by LornesAV » Logged

2008 Z71
mnpewter04
Full Member
***
Offline Offline

Posts: 59



Awards
« Reply #14 on: 01/12/12 08:03 PM »

If you're logging a +7 LTFT (Long Term Fuel Trim), that means you're running extremely lean, so the drop in mpg makes sense. Keep in mind that weather has a lot to do with LTFTs as the air gets more dense in colder temps, using less fuel.
If you've been running your tune for more than 100 miles and you're still showing +7 (using the Predator's data logging feature), go into the tune and adjust the injector slope by -7. Run it for 50-100 miles and log it again. You should be near zero in your LTFT.

Read the stickys on the diablosport forum as well. They'll help you a lot!

Good luck,
MM

So i would need to do a data log, is this done while driving and hooked up to the predator?  And is this adjusted in the performance tune?
Thanks
Logged

04 Silver Birch Metalic
MSD wires, Spectre CAI, Gibson Dual Cat Back kit, Predator Tuner
DooTalk.com
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #15 on: 01/13/12 03:41 PM »

So i would need to do a data log, is this done while driving and hooked up to the predator?  And is this adjusted in the performance tune?
Thanks

Yes there is an option in the diablo menu to data log but first go to the diablo sport forum. 06monte has a thread under predator, GM Gas for the proper items to log.

After filling up mine the mileage back from Springfield is at 14.8, the DIC read 19.6 gallons used the actual fill was 23.227 nearly four gallons difference. This happens about once every six months.  Thumbs down one of the frustrating things to monitor my AV operation to show if tune up or some kind of maintenance needs to be performed. Or is it just the gas stations pumps way off.  Huh If that is the case then the next fill should be less than the DIC. I have had that happen as well.
Logged

2008 Z71
LornesAV
CAFCNA 2012 Premium Member
Full Member
*
*
Offline Offline

Posts: 805



Awards
« Reply #16 on: 01/22/12 07:26 PM »

So i would need to do a data log, is this done while driving and hooked up to the predator?  And is this adjusted in the performance tune?
Thanks

Have you invested in the tune from 06monte? If so any improvement, I would have to say I had had no improvement from the stock diablo tunes. I am going to put the factory one back on for this week and see what happens. I checked one of my 02 sensors today didn't look to great so I have them on order. God bless the GM mechanics for having to deal with what should be an easy change out but isnt.
Logged

2008 Z71
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2011, Simple Machines Valid XHTML 1.0! Valid CSS!
Page created in 0.067 seconds with 25 queries.
Official SEMA Member ChevyAvalancheFanClub website are the rightful owners as indicated in the ALT TXT tags provided.  Chevrolet, Chevy, Avalanche, PRO-TEC, PASSlock, Midgate, the Chevrolet bowtie logo, Avalanche logo, and their images are registered trademarks of the General Motors Corporation and are used with kind permission as approved by Chevrolet Public Relations, Chevrolet Brand Management, and the Chevrolet Legal Department (thanks Chevrolet!).  OnStar and it's logo are the property of OnStar.  XM, XM Radio, and the XM logo are property of XM Radio.  I'm just a little guy so don't even think about suing me.  It's recommended you read the Privacy Policy and Terms of Use of this website.  The Chevrolet Avalanche Fan Club of North America is a proud member of SEMA, the Specialty Equipment Market Association.  All content appearing on this is protected under international copyright , 2002 to 2008, All Rights Reserved