Hey guys after installing the CAI and superchips "performance setting" other things last month I was getting anywhere around 13.5 - 14mpg average depending on my commuting week.


Well last weekend I got a stereo and alarm installed. My commute or driving style hasn't changed but I'm now averaging 12.5mpg (full tank fill, 160miles by 1/2 mark) or so... any suggestions? I do have the Evap Code engine light thing... but that's always been there.


Is it possible they reset or messed something up with the chip setting when they disconnect the battery / installed electronics?

 

What are you using to calculate mileage?

 

Same gas gauge marker line to needle line Left side of needle touching right ride of marker line on full and half tank mark. I don't use the overhead display thing cause it doesn't seem to be accurate... in fact its usually more generous as to the avg MPG's

 

Could be any number of factors. Try calculating manually for a couple tanks. Installing an alarm system should not have done anything.

 

Agreed, alarm is electrical, not mechanical.

Poor fuel, heavy foot, plugs, air filter, tire pressure, head wind, bad front O2a and more all have to mileage

 

Tires & air filter new, plugs only have about 13k (44k miles on truck) ... been using same gas station. Hmmm..ill check things out.


thanks guys

 

I'm sure they disconnected battery long enough to reset the PCM. It'll relearn...

 

If it's a hemi its due plugs again.

 

His plugs have only 13K. Where do you get that? As for mileage, there is only one way to accurately determine the mileage.

 

Nope it's 4.7.reprogrammed it last night and there was an immediate difference in throttle response and power. I'll fill gas to the same line as before and re-calc the MPG's this week