I need some help! New to this web site, have a '97 trans am. my problem is that i have a miss at high rpm's. the car runs fine all the time, when i floor it and it gets to about 4700+ rpm's it misses just a little bit but then shifts out fine. i've replaced the coil, wires, plugs, it's hypertech tuned, don't think that has anything to do with it though. it just started doing it recently. if anyone has any advice or similar experiences, i'd appreciate the feedback. thanks...

 

i don't have a cam or headers, but i was wondering if for some reason the knock module would be the cause. doesn't it retard the timing?

 

What kind of miss, does it bog down for a second, or does it just skip to the higher rpms. You might feel a retard in timing, but without headers or roller rockers you shouldnt be getting timing retard from the knock sensor. Does it do it in all the gears or just first. Could be anything, wires, plugs, opti, shouldnt be the coil even if it was still stock.

 

Did it happen all of a sudden, or is it getting progressively worse?



Jason

 

Knock retard will feel like a loss of power, maybe similar to missing. The module is just a "filter".... the sensor hears the knock, sends a signal to the module, the module filters out things that aren't typical of knock, and the signal continues to the PCM. Then the PCM pulls timing in response. That would feel like a "surge" or maybe a soft "miss". A scanner will tell you if you have knock retard.

Are you sure the wires are still OK, the plugs were gapped and installed properly, and there is no corrosion anywhere in the ignition system... coil terminal, plug terminals on the Opti?

And..... the big question... what is the condition of the OptiSpark? How many miles? Recently exposed to excessive moisture... leak from weep holes on water pump?????

 

the opti-spark was replaced about 2 or 3 weeks ago, it had just started missing a couple weeks before that went out, so i thought it was the optispark... put the new one on and it's still doing it. i put the new coil and wires on the day i posted the first message. it's an MSD coil and Taylor wires. it runs much smoother with these, but still misses. it's in every gear too, not just 1st or 2nd. the plugs are pretty much new, but i really don't know what else it could be.

 

missed a couple of questions, it doesn't skip to higher rpm's, it just bogs down for about 1/2 second, and it just happened all of a sudden and has been the same since, about a month and a half or so.

 

Try an LT4 knock module. $30, it cant hurt, even if it doesnt fix your current problem it will help now and more in the future with RRs and Headers.

 

bad 02 sensors wouldn't cause a miss this noticeable would they?
i guess i'm going to try the lt4 knock module, don't have much left that could be wrong...