Have you checked the operation of the EGR valve? Use your fingers to make sure the diaphram is closed and remove the vac line (plug it with something). Then drive it and see what happens. Just a thought................

 

okay,the more I learn the less I know,last night I drove on highway after diconnecting battery for about an hour,car ran perfect,no stumble or knock,temp stayed at 165,then at about 80 miles(after disc battery)stumble was there in sixth below 2000 rpm( about 80 mph),above 2000 rpm in sixth or 5th at above 60 mph there was no stumble.If I gave the car throttle(floored) at a low rpm while in the same gear,not dropping to a lower gear,it stumbled,sputtered until rpms came up then went away,I disconnected battery overnight,drove car took up to 60-70 in 6th floored it below 2000 rpm no stumble,drove normal again,until temp got up to 210 in traffic when stumble came back under a load in high gear and is still present regardless of temp,but it still pulls away clean.Its like once the comp learns its there,I have to reset it and doesnt come back until temp gets hot or driving the mileage(about 80) could this still be my opti or EGR(I have no service light),or is there anyway it could be the new 1LE bellow(it does have the Intake air temp sensor connection in it)I guess i could put the stock one back on and see what that does.

 

we tested mine today with a spark tester and found out that my coil wasnt hitting hard enuff so I swapped it out for the stock one and some issues went away. We retested it and the spark was nice and hot but still jumping around. So dont forget the coil or ICM

 

don't blame the opti!!! I had a new one put in and I have the exact same problem you do it sputters and hesitates when hot but runs like a raped ape cold I traced everything and cannot for the life of me figure it out so I put a 160 thermo in and it goes away until I idle for a while then it is back, maybe its just every few cars act like that??

 

This might be a stretch, but try unhooking all of the ground wires off of the ground stud for the PCM, and then pull up the ground lug and clean that really well too. It is located on the passenger side fenderwell. It is about 8" away from the red plastic junction box. It is a sheetmetal screw where it screws into the body and gets really corroded. You want it so the metal is shiny again, perfectly clean, and the same for all the wires that hook to the stud.

Please try that and let us know if it works for you.

 

I would replace the coil with a GM one.Might change the coil wire as well(did you save the old Coil?).Might do the cheap stuff first.(My opticrap was saturated when I totally lost my water pump,and it survived.Clocked at 105,000mi now.Still books to the limiter even in this 97 degree heat today.Hope this helps.

 

I replaced my coil as well and it did not go away but I will try the ground wire thing and see if that helps. I did think the coil was getting heat soak so I might be moving it off the head and mounting it somewhere cooler along with the module

 

i put my old bellow back on no difference,I'll try the ECM connection clean tomorrow,but what does the coil have to do with resetting the computer?still have old one though,but its a pain to change,last resort is take it to dealer I also can see that it doesn't matter what the temp is it still does it once it starts,until i disconnect battery for awhile,then its gone until temp gets above 210,or over driving about 80 miles,makes no sense

 

At what time / temp does the EGR start working ? Could that be the problem ?

 

okay,this has become very perplexing and annoying,the problem only goes away now after I disconnect battery,and temp gets up to where CAGS is active(about 175).I tried cleaning all PCM connections,and a few others with electric cleaner,no difference.Above 2000 RPM the car behaves normal and has plenty of power,under it, it hesitates,sputters and knocks until above 2000.what the hel can this be?Anyone else have any suggestions before I take it to a shop, or wreck it pulling out.

 

when you guys say you replace the opti unit, does that mean the whole unit or just the cap and rotor, my car is doing the cutting out thing when hot, i had someone replace the opti cap and rotor and it still does it.

 

I would now tell everybody to check your ECT and its connections! if your fans arent acting up or are not working at all or working too early, might be that! Plus that will make it run richer and/or make the timing off.

 

I forgot to say that from what others have said, the opis dont like the replacement cap/rotors. Its the high voltage part that ruins it. I dont know how but it does so Im guessing it ruins the optical section.

 

I vote for the opti. My 94 ran great until it reached operating temp. Then it started missing (mostly under load, no matter the gear- A4) My tach needle was bouncing erratically as well.
Mine kept getting worse and worse, and finally it got to the point where it would not start all the time.

Seemed like the optical portion of the opti would get weak after it was warm. I put a new opti in and it fixed the problem.

Perhaps it is just coincidental that when you disconnect the battery- as it may give the optical portion a chance to catch its breath, and work correctly for a while. You may have entered the downward sprial- you may see the missing come on quicker and quicker. If it is anything like my car, you will have about 2 months of troublesome driving before it will have trouble starting.

Just my experience- Good luck

Dan

 

Mine Has been running like that for 2 and a half years (same symptoms) I have replaced everything but the opti and nothing changed. I originally thought that if it was the opti it would fail completely but 2 and a half years later it is still running the same. I am out of ideas.