I've got a buddy who has an 03 Avalanche that isnt running 100%...and thats putting it nicely.

It's running pig rich, is way down on power, gets HORRIBLE fuel mileage, and is pinging when he goes down the highway underload.

He's had it at the stealership several different times, and they have used a Tech2 and supposedly been able to remedy these problems, but are telling him they cant leave the changes in that they make.

My advice, was outside of pony'ing up for LS1edit...was to get a Predator, and see if those guys can help him out with a custom tune. But he is a little hesitant because of the stealership also telling him that if he alters the PCM in any way, they'll void the warranty, and that they can tell how many times the PCM has been "plugged" into, and what changes were made...now Im not dumb, and I am pretty sure they cant do that, otherwise I would have had issues on my 03 GMC HD Dmax, when I forgot to remove the programming and it went in for service.

Last thing, he said when he bought the truck it was fitted with California emissions equip. Im assuming that is probably hampering performance too.

Any other ideas that you guys might possibly have? I tried explaining to him that most dealerships and their techs dont know **** about the vehicles they work on...

 

It could be a number of things. Does the SES light come in? If so the code that goes along with that might help. Things that I would start to look at are the MAF and 02 sensors. I've seen this problem in the past and it was cured with a new 02 (it was bank 1, sensor 1).

The dealer can't deny warranty coverage unless your friend does something that actually causes the problem -

Legally, a vehicle manufacturer cannot void the warranty on a vehicle due to an aftermarket part unless they can prove that the aftermarket part caused or contributed to the failure in the vehicle (per the Magnuson Moss Warranty Act (15 U.S.C. 2302(C)) . For best results, consider working with performance-oriented dealerships with a proven history of working with customers. If your vehicle manufacturer fails to honor emission/warranty claims, contact EPA at (202) 260-2080 or www.epa.gov. If federal warranty protection is denied, contact the FTC at (202) 326-3128 or www.ftc.gov. For additional information, check out the following links:

Consumers Bill of Rights - http://www.enjoythedrive.com/content/?id=8123
What You Can Do If Your Warranty Is Denied - http://www.enjoythedrive.com/content/?ID=8124
Federal Warranty Laws - http://www.enjoythedrive.com/content/?id=8128
Vehicle Manufacturer Warranty Contact Phone Numbers http://www.enjoythedrive.com/content/?id=8129