93 runs rough when warm

[joellthomas]

My 93 (auto) runs smooth and strong after first started and the engine is cold. When the temp gets to 1/4 it starts to run rough when the throttle is opened to accelerate. When the temp gets to 1/2 (normal) it will hardly accererate and shutters bad as the throttle is opened. Runs ok while running at a steady speed. Checked fire at each plug- OK, replaced fuel filter- No Help, Don't see any vacuum hoes off.
help!!

[joellthomas]

wus a plug wire, started missing at idle.

[hontoy]

Originally Posted by joellthomas

My 93 (auto) runs smooth and strong after first started and the engine is cold. When the temp gets to 1/4 it starts to run rough when the throttle is opened to accelerate. When the temp gets to 1/2 (normal) it will hardly accererate and shutters bad as the throttle is opened. Runs ok while running at a steady speed. Checked fire at each plug- OK, replaced fuel filter- No Help, Don't see any vacuum hoes off.
help!!

sounds like your ecu is trying to lean out your air/fuel mixture when engine gets warmed up. check your engine coolant temperature sensor. signal voltages should be around 1 volt when engine is warmed up or in closed loop.

[OonePrelude]

Is your check engine light on? I had this exact same problem a little while ago. It turned out to be the MAP sensor. It was going bad. Easy to replace and is only ~$75.

[joellthomas]

thanks for replying. It actually turned out to be a simpler fix. a plug wire was jumping over down at the plug. it finally started doing it all the time so even i could find it. replaced the wires, dist. cap and rotor. boy was that rotor hard to get off, had to use a puller.