I just put together a front mount intercooler on my truck and now it is running way rich. The intercooler is an Ebay special 20X12X3 and I used a 3 inch piping kit off of Ebay and pieced together. My maf is about 8 inches before the TB and the BOV is about 8 inches before the MAF. I also just installed a 255lph fuel pump at the same time but I wouldn't think that would have anything to do with it. My PE is set to 11.9 which it was running close to 11.5-11.9 AFR before I made these two changes. Now as soon as it goes into PE it shoots down to 10.0-10.5 AFR or shows rich which is below 10.0. This is without any meth. What gives?

 

Sounds like your fuel pump was not keeping up so when you put the new one in it richened up a ton

 

I was thinking that too but would it make that much of a difference at only 30% throttle? My fuel pressure looks the same. It was 60lbs before the new pump and it is about the same now.

 

Here is a little more info. I checked my fuel pressure this morning and it is 52 at idle and 62 with the vaccume line pulled off of the regulator. I think that is about 4psi higher than it was with the stock fuel pump. I logged my drive to work this morning and my LTFT's are at -15% almost all of the time. At idle the LTFT's are -5% to -10% and they shoot up after I start giving it any throttle. On a good not my intercooler is working well. My IAT's were only 2 degrees above ambient this morning all the way to work. The only other things that I changed this weekend were the battery and fuel filter. Could the higher fuel pressure affect my AFR that much?

 

Ya, More fuel pressure will defiantly richen it up. With -15 trims, it's trying to pull a ton of fuel.

 

I decreased my VE table by 15% at lunch today and it only brought my LTFT down to about -11%. Do I need to change the IFR to compensate for the added fuel pressure or should I just keep lowering the VE table until my LTFT are back to normal?

 

did you reset your lift's? They will need some time to relearn, also unless your running SD, the MAF is doing the fueling over 4k rpm.

 

How do I reset the fuel trims? I'm still running the maf but I can't get anywhere near 4k rpms. My truck goes so rich when it gets to 0 vaccume it stumbles and bucks.

 

In the scan tool under calibration. You might just have better luck with putting your VE table back and try pulling 5% out of your IFR table and see where that gets ya till you have time to do a FULL VE/MAF autotune with the proper IFR table.

 

It could be your intercooler restricting air flow, and the PCM adding the same amount of fuel making a rich condition.

Double check the air measurment, scan now and compare it with an old scan at the same RPM, KPA, and MAF.

Check differential pressure across intercooler also!

Let us know!

David