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Discussion Starter · #1 ·
I've been having problems with my 92 Convertible LT1. Car starts and idles fine, but hesitates and backfires under acceleration until about 2,500 RPM, then accelerates normally once foot has been removed and reapplied to gas pedal. Car revs normally with no hesitation while in park. Problem only apparent while driving. No difference wheather operating temperature hot or cold. Scanned computer, found no codes reported.
*Parts replaced: Optispark, plugs, wires, fuel pump, filter and air filter.
If anyone has suggestions, please advise.
Thank you.
 

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I've been having problems with my 92 Convertible LT1. Car starts and idles fine, but hesitates and backfires under acceleration until about 2,500 RPM, then accelerates normally once foot has been removed and reapplied to gas pedal. Car revs normally with no hesitation while in park. Problem only apparent while driving. No difference wheather operating temperature hot or cold. Scanned computer, found no codes reported.
*Parts replaced: Optispark, plugs, wires, fuel pump, filter and air filter.
If anyone has suggestions, please advise.
Thank you.
Check your plug wires again and look for possible misplaced ones.

After I replaced my opti spark and hooked up my plug cables, I must have swapped two in the wrong place because it was back firing at start up.
 

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It could be a EGR problem. The EGR valve is vacuum actuated and when you take your foot off the gas and then accelerate again that would give the EGR a kick if the valve was sticking. Also, if you replaced all those parts because of this problem with no fix suggest that you troubleshot to find the real problem. Guessing and replacing good parts gets very expensive, proper troubleshooting is the professional way to do things and is much cheaper..............
 

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Use a DVM & check your TPS. What plugs did you use? What plug wires did you use? When did it develop? A stuck EGR will cause an idle problem. You may want to try some BG44K or some Seafoam, may have some injector problems. Good luck & keep us informed.

Toby
 

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"A stuck EGR will cause an idle problem" Right, if it is stuck open at idle, but it can also cause problems if it is not opening/closing properly at other engine speeds but still closing at idle. Anyway, point is just do not throw money at the problem, use proper troubleshooting procedures. There are many things that can cause acceleration problems...........
 

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I agree with slicktop, it could be an EGR problem. I would however, before I replace or do anything, check your fuel pressure, just to elminate any other possiblities from the fuel tank to the injectors.
 

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"A stuck EGR will cause an idle problem" Right, if it is stuck open at idle, but it can also cause problems if it is not opening/closing properly at other engine speeds but still closing at idle. Anyway, point is just do not throw money at the problem, use proper troubleshooting procedures. There are many things that can cause acceleration problems...........
If the EGR is stuck closed, it won't do anything. You Can block off the EGR & won't have any problems with driveability. It is supposed to open @ cruise which adds exhaust back into the intake to help burn better. Less performance & helps with the emissions. So what kind of driveabilities will it cause if it sticks closed? I've seen his driveabilities be in the ignition system & in the fuel system. Not a fuel filter since high rpm's are ok, not a plugged exhaust because high rpm's are ok. Could even be poor fuel. I got gas one time & under 2500 rpms it ran terrible. Drained the fuel & put new from a different station & it ran great again.

Toby
 

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Discussion Starter · #10 ·
Hesitation Problem Found!

Mechanic told me the ECM was bad so I took it in to local rebuilder who found nothing wrong it. I reinstalled ECM car ran great. I checked ECM pins and connectors that looked a little dirty. I cleaned the pins and connectors with contact cleaner. The car has been running great.
 

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Mechanic told me the ECM was bad so I took it in to local rebuilder who found nothing wrong it. I reinstalled ECM car ran great. I checked ECM pins and connectors that looked a little dirty. I cleaned the pins and connectors with contact cleaner. The car has been running great.
Funny how all these things work out!:food-smiley-019:
 
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