Ok, i know ignition issues can be a pain to pinpoint exactly what it is, but maybe you can steer me in some direction, what its been doing is, at the track in 4th. gear it starts developing a slight vibration, seems like the more fuel pressure i give it, it gets worse & the car will slow down about .2-.3, BUT ever sence i went back too the stock tune (unloaded & sold the Hypertech), i went back to the track last night to see if it ran better, on the first pass it pulls off my best run ever (13.54) but in 4th. gear at around 5000 rpm all of a sudden it went "POW" & kicked back abruptly & sounded like it came out the exhaust, it did it fast & it was over, as i rounded the return road it went pop-pop slightly through the exhaust, then all was good, went back to the pits, i decided to raise the fuel pressure, made another pass an hour later, did the same thing, but its ONLY doing it in 4th. gear, 1st., 2nd. & 3rd. its fine, i'm shifting at 5900, that pass it slowed to a 13.85, the last few times i've been at the track (with the hypertech installed) its been feeling (shacky) in 4th. gear, but not untill i went to the stock tune is when it popped back on me, now i realize something is wrong, the car has 158K miles on it, the plugs/wires are not that old, it has full bolt-ons, i'm sure the Opti & coil are original, what should i look at, does this sound like more of a coil issue or maybe the Opti??

 

Anyone have any thoughts?

 

Why are you increasing the fuel pressure?

 

At first i though maybe it was leaning out, but dumb azz me got in a hurry & forgot to disconnect the vacuum when checking it, so it read 33 psi, when in reality it was 43 off the reg. turned out it was fine, but my main concern is this hickup it developed, i dont know how to accually explain it, but the car definitly kicks back when it happens, it only does it in 4th. gear & happens 1 time only, not like its bam-bam-bam, i'm starting to wonder now if its not something in the PCM on its stock tune thats cuasing the problem after pulling the hypertech, thats the only thing i changed, & it never did this before, it doesn't miss or surge, starts very easy, its almost like it shuts down abruptly, can the PCM be checked to see if its throwing codes?

 

Any codes???

 

Sure, you can check the PCM for codes. You need an OBD-II code scanner. As low as $40 at Harbor Freight, or have your local auto parts store scan it for you. If you have someone scan it, get the EXACT code number(s) ("Pxxxx"), and not just some generic description off the store scanner.