My dad has a 2003 Tahoe 5.3. He's towing an RV trailer that weighs somewhere around 4500 lbs up through the Siskyou's right now. Prior to installing the cold air intake, he was getting around 12 MPG towing... Now he's getting 9 - 10 MPG, and it feels like it's running out of power over about 4000 RPM when it dumps into 2nd gear on a hill... Has anybody experienced this? And as I alluded to in the title of this thread, does the ECU typically need to be reprogrammed with a tuner after installing a cold air intake? Any help would be appreciated. Thanks!

 

The CAI probably isn't the cause. With the modern PCM, "lowering" the restriction on the air intake rarely has any effect on the gas mileage. It may see more air based on the MAF and O2 sensors but it will adjust the fuel accordingly. Maybe it's some other mechanical problem, driving habits, vehicle loading, or just unrealistic expectations. Try restoring the factory setup and see if things will go back.

 

He was going to try a couple things over the next couple days and see if there is any change. I should have more info in a couple days... It could just be something mechanical. Who knows... Thanks for the info...

Anybody else want to throw in their 2 cents worth?