ok having a weird problem with car. took car got a dyno tune.
runs flawless takes WOT on dyno etc. i start driving home and i punch it and it pings and pops acting like its not even tuned at all. then driving it back to the tuner i try another WOT and it runs excellent. does same thign back and forth. one minute it will haul *** next itll be like F-U...
So we looked at the tables or w/e and everyhitng is the same from when it ran like **** poppin and ran fine. everything was fine except misfiring.... any idea? 02's are reading fine injectors are at 98%... car made 404rwhp
Stock fuel pump. half tank gas. i wouldnt think its the fuel pump because its allways running and i dont see how one minute it can be fine then next it couldnt supply enough fuel... Lost!!!

 

Without knowing any of your mods, my best guess would be your Engine Coolant Temp sensor is broke/ intermittently making contact. Easy to break during header installs.

 

Gotta get a data log while its doin it.

 

If you have a situation where fuel trims very a lot, cell to cell,
you can have this sort of action - leave right from idle where
you have +15 LTFTs and you'll be pig rich at WOT, leave with
a more gradual roll-on of throttle and step into WOT from a
mid-range cell with a -2 LTFT and you'll maybe get your tuned
12.7:1 AFR instead of 11:1. Scan tool would tell you about this
if you logged the right things.

 

You might of answered your own question, Injectors are at 98% ? I am assuming you are talking about duty cycle..This could inherently be causing the intermittent problems..

 

right now were checking wires for crank position sensor.

 

ok guys only does it in 1st and second gear... what could cause this

 

Sounds like a loose wire. The engine temp and IAT sensor can do this.

 

Turned out to be the Crank Position Wires were touching the top side of one of the header tubes where the SLP's snake around eachother. Found that out when I dropped the starter to try a different Crankshaft position sensor. We changed the sensor as well just to be safe and to be sure that the shorting out didnt hurt it. He picked up the car up last night and I believe its all good now