So, heres the symptoms of my cars problems.

--idles irradically when its cold, but seems to run fine.
Once it heats up, it idles worse, and misses throughout most of the rpm range. The car has been doing this for two weeks now, without getting any worse. I also noticed that the voltage jumps, when the car is at idle, it sinks into the low side and the engine misses seem to correspond to the voltage sinking. The voltage is fine when im in gear at anything over 800rpm.

--now, the plugs are new, as are the wires, coil and ICM (and spaced them about 1/2" away from head). The problem seemed to start when I changed to longtubes, even though I replaced all of the above mentioned parts. Im starting to think its the opti, but the car has 48,000 miles, and only 8,000 on the optispark. Would the voltage be affected by a failing opti? What else would you suggest?

 

Well it could be a vacuum leak. Your LT's could be leaking at the heads...which is throwing off your O2's, which will make your car run off balance(meaning one side leaner/richer than the other) which would cause it to run rough. When the car gets warmer, the leak can become worse from the expanding of the heads.

Mine does pretty much the same thing yours is doing.

Cold startup..I think it runs rough because the last time you turned off the car, the computers settings(LBL and RLB 'are storing numbers in the computer which are effected by your vacuum leak)

After a few minutes before the headers are leaking air..because they're not warm enough yet...the computer gets back into running normal.

Then when it gets hot, the air thats being let in before the O2's is freaking out the computer, screwing it up again.

Thats pretty much what ive established whats going on with my car...not sure if its accurate, but does that make any sense?

My left bank(driver side) was running lean, so i just replaced the driver side header gasket, but its running worse now. I think I got the wrong gasket though, because it didnt match up...so i made a post about that.

 

hmm...thats interesting, im going to have to look into that.

I also should note that I just replaced the 02s too, because I burnt the wire on one....

the driver side 02 was clean, and the passenger side 02 was pitch black...


maybe thats why

 

if you burned a 02 sensor, I can almost guarantee one of those plug wires is resting on a header... check again and again those plug wires, they make same stutter.

 

I have the same problem with the voltage jumping at idle and a miss when it warms up.

I was thinking it might be the battery or alt because of the voltage thing, but what else could effect that?

My opti is pretty new also (less than 10k on it).

 

My driver side O2 is always Pitch black.....ive replaced them several times, yet it continues to throw the code 44(Left O2 running lean).