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Discussion Starter · #1 ·
I Have a 94' Z24 w/ about 61,000 miles, and have been having problems for about the last year with a rough idle. I have thoughly cleaned the throttle body, have had the injectors cleaned, have had the plugs changed and new wires put on, and had the EGR valve replaced recently, but nothing has worked and the idle has increasingly been getting worse. The revs bounce sharply up and down between 800 and 1,100 RPM and the car twinges and shakes annoyingly as if it is missing. No one I have taken the car to has been able to figure out what is wrong.
The condition also happens at all engine temps. What Could it be?
 

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Discussion Starter · #3 ·
I have not replaced the coil packs. I didn't think about them. I also wonder if it could be the fuel pump, because sometimes the the revs drop enough to where the engine stumbles and almost stalls out at idle. How can I test my Coil packs?
 

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I had the same problem...I changed my SparkPlugs and wires.. and it much more stable now.
Mine is a 92 Sunbird w/3.1L, manual transmission

I also have a weird problem : when the car is cold(running for 2-3minutes), the engine is EXTREMELY powerfull(in 2nd gear, I put the gaz pedal at the end.. and it spins) But when it is running since 1hour... even in 1st gear, it doesn't spin! The car is slow... and the acceleration is not really good.

Only when the motor is hot!

Does it have to do with the air intake? I haven't bypassed the throttle body heater yet.

Thx for the help
 

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Discussion Starter · #5 ·
the tempurature of the throttle body should not make that large of a difference in performance. What type of air filter are you running and how many miles are on your engine? My car too is a manual, and also is much more powerful when below normal operating temps. My engine also sort of stumbles after shifting into a higher gear and 1st applying the gas when the engine is cold.
 

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There is 158 000 km on the car...
that about just under 100 000mi.

The air filter is a "FRAM", it's about 2 months old.

I had to take it today... and when the engine is hot(temp @ 1/4 or more),A Honda civic is faster than me!

I first thought it was the sparkplugs.. but there were changed recently(AC Delco).
 

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Yeah, check if there is fire on each sparkplug... A friend of mine had this problem on it's V6 Jimmy(TBI). It's hard to tell when there is one cylinder not functionning on a V6, 5 cylinders are OK to run(not smooth but worked for him to get to the garage!)
 

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my engine jumped and had that bad idle around 800 to 1100 also, a shop replaced my O2 sensor and the fuel filter and it ran great. And on a side note I had a good time a few nights ago smoking a Camero, it only had a 3800 engine, but the look on his face in my rear view mirror was worth it.
 
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