Stumble on load, only when warm/hot

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Ok, the basics- 92, 6spd, 125K miles, new opti at about 60K thanks to water pump, replaces wires and coil about a year ago, computer replaced 3 years ago, coated SLP shorty headers.

Here is the deal, cold to normal operating temps- no problems. If I am in stop and go traffic/stop and restart after short rest/or otherwise get the under hood temps up, it stumbles hard under moderate to hard load.

Thoughts/suggestions?

It starts fine, and has no other symptoms or issues.

 

[tdr1919]

I just read/viewed on another forum which has a few video clips from a injector rebuilder. There were multiple examples of injectors and failures, along with the symptoms. There was one example where the injectors were fine when cold, (resistance & spray pattern) but after the injectors heated up, you could see the spray pattern change and become inconsistent. This was what "root cause" of the owners stumbling problem.
Have you dona a tectron treatment?
Of course there can be other things like egr, have you checked to see if it was throwing any codes?
Tom

 

[Topless]

It has been a while since I ran an injector cleaner.

No hard codes (SES light off), and I never learned if you can jumper the diagnostic port to get the computer to flash them without a code reader.

 

[lone73]

so your current opti has 65K on it?
My '96 has had those symptoms twice. both times the opti was bad.
good luck

 

[Topless]

Did you have any other symptoms? I hate to dig in and replace an expensive item and have it not be the cause.

 

[Hib Halverson]

In what condition are the plugs, plug wires and coil?

 

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All are a year/year and a half old. One of wires got up against the exhaust for a little bit (very short time), but didn't burn. (very small discoloration spot) I since have kept it from touching anything, and have added insulation to the spot it touched just in case.

I figured if it were bad, it would be bad at all temperatures. Yes/No?

 

[John Robinson]

All are a year/year and a half old. One of wires got up against the exhaust for a little bit (very short time), but didn't burn. (very small discoloration spot) I since have kept it from touching anything, and have added insulation to the spot it touched just in case.

I figured if it were bad, it would be bad at all temperatures. Yes/No?[/quote]
The answer is no I just went through the month of October trying to figure out why my car ran great until the temperature got to about 185 and then it backfired and lost power and basically ran like it was only on about 4 cylinders then it would suddenly take off again especially if I had it in second gear at or above 3000RPM but it would misfire above 4500RPM.

The answer was I had two bad plugs and when I replaced them it ran better but still missed. Next I ran the engine in the dark and found that I had sparks flying from the wires to ground. I replaced the wires and used vacuum hose around the wires were they came near each or could jump to ground. That was the fix and oh yes I was working with new wires and plugs that I had put in on the first of October.