I just had a new Opti as well as new platinum plugs and wires installed on my 95 Z and it still has the miss and stumble from idle to 2,000 RPM's After that it revs fine. Also when in 6th grade and accelerating, the engine will shake and rattle and lacking power to the point I have to downshift to 5th to accelerate.

I di dnot get the cap replaced on the Opti spark. Could this be the issue? thanks.

 

How do you buy a distributor without a cap and then put the old one on it Doubtful that's your problem but I fail to understand why you bother with plugs and wires but leave the rest of the high voltage side of the distributor there. Why did you even change any of the distributor to begin with? Did you think the low voltage side was creating your problem? If it were, you would have different symptoms and you would be getting a code. Did you look for a code?

Your symptoms are more indicative of a stuck EGR.

 

http://web.camaross.com/forums/showthread.php?t=504532

i have almost the same problem except mine is hard to start...

you didn't buy Accel did you?

 

I am not Mr. Good wrench, I bought a Opti from Advanded Auto, while it was there, the oil from the water pump I was told by the mechanic coated some of the opti , and wires. He wiped them down, tool it for a drive, it was still missing just below 2K. Bought the plugs and wires , same deal.

I was thinking ignition [robelm, possibly the coil cause of the miss and stumbling. EGR is new to me and was never replaced

As far as the code situations. I never really trust that for the fact that my Dad's had ignition problems. A friend of ours had a diagnostic and left it plugged in and drove it for 70 miles and it did not throw any codes but ran poorly the whole time.

 

I have the same prob.. with my 94z M6..in 6th the car shakes and stumbles until i rev it to like 3grand or so then its fine...i checked for codes at work and found nothing with the gm scan tool..so coil might b a problem..but lemme know what u find out...good luck

 

Stumbling may be vacuum leak.

 

I'm hoping it is a coil, possibly a coil wire. Then once this problem is solved, I will be looking into a LS1-esque setup and finally sh&*can the scourge of the Opti and all the sufferings it causes once and for all.

 

Exactly what did you replace on the Opti? Are you saying you bought a new rear 1/2 of the distributor from Advance Auto and had it installed, using the "old" cap and rotor? If they reused the old cap and rotor, did they at least check the plug and coil wire terminals for corrosion?

At what RPM are you attempting to accelerate in 6th gear?

Did anyone check the coil? Did anyone check the IC Module? Was the PCM scanned for codes - you may not trust them, but many of us have been able to cure a few problems with a bit of scan data? If they replaced the plug wires, why didn't they replace the coil wire, which typically is included in the wire set?

 

I did find out that the whole Opti was replaced, not 1/2 as I thought and posted.
Most of the mechanics and shops in my area only have a OBD2 diagnostic tool.

I will have to ask if the coil wire was incldedin the plug wire set. I did not recall seeing one. As far as accelrating in 6tth gear, it is normal 6o mph plus RPM which is jhyst below 2,000. I am not nailing the throttle with the RPM just above1,000. I have no nticed that there is a miss in other RPm range whiel accelerating from a stoplight. One off idle, around 2,000 then between 2,500 and 3,000.

I was asked by a friend it could possibly be the ignition module.