Thread: 99 gtp sluggish after mods.. please help

Put stock pulley back on, try again.

If you don't want to re-tune it that is.

Originally Posted by onalky87

Narrowband is in the 900 range. Ltft is -1.5 wot and +10idle stft is 0 +-3. It's just frustrating that I picked up maybeeeeeee .2 from headers and a 3.5 when everyone else picked up .8-1.0. I knew it was a freak. But I've seen many cars near by my that went 14.4 stock and now do 13.5 with my mods. Thats y I feel like I'm missing something.


The tune I have is the canned tune that my buddy has on his 98 gtp that went 14.0&98. He has a cat and I don't only difference in our cars. I have stock catback as well

Maybe my exhaust leaks r making it that slow? Ik it leaks at crossover on both ends which is before o2 sensor. Not bad u can't feel it or hear it really. But when seafoaming it smokes under good pretty good bc of it

I would start by fixing those leaks. The 02 readings will be wrong with those leaks and the car is probably running too rich because it thinks its too lean. I would fix those leaks and relearn the fuel trims. Then see what happens. You should be a lot faster.