I have a 2007 WRX STI tuned for ~300whp.
Engine is forged, using CP pistons, rebuild because of a crack in 4th. Have CAI, 20g turbo and 750cc's with a custom remap and varex muffler. Stock TMIC.
I also have a AEM wideband next to defi EGT, boost and fuel press.
When remapped, or battery disconnected for a reset, the car is almost perfect for a 100 km or so, then a slight hesitation starts building around ~2500 rpm before AFR goes crazy and car feels jumpy, sluggish, meaty, unresponsive and under powered after about another 100 km. I've been reading and reading and reading and trying to learn from forums, my tuner and my mechanic and I'm about to go crazy.
At WOT no hesitation but under powered
We've changed MAF, both o2's, checked for pressure lost for both intake and fuel.
People all around forums seems to be frustrated about the same problem.
08+'s are changing their fuel system with '07 ones trying to get rid of the hesitation, putting o rings or adding capacitors to dumb down the knocking sensors, playing with AVCS settings and so on.
The most two common reason seems to be the remap or knocking sensor picking false knocks because of the extra vibration brought by different parts like a loud exhaust system.
I'm almost at the verge of selling my car.
I need a REALLY good tuner to help me out, if he can, remotely.
I'm willing to cooperate for any data requested.
Can you help me?