Mechanics

89 RUNS ROUGH

1989 Chevrolet Corvette • 2WD Manual • 60,000 miles

1989 Chevrolet Corvette Misfires after warmup
89 Corvette with 60,000 miles runs rough and misfires after it warms up. It starts good, idles and runs fine for about 5 - 10 minutes until it warms up. Recently had four fuel injectors replaced, new plugs & wires, new distributer cap & rotor. Fuel pressure checks out good. No check engine codes showing. What would malfunction on warmup? Could I have a faulty ECM?

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Philmsherman
April 28, 2011.




After ecm goes into closed loop the o2 sensors come online check them first

Merlin2021
Apr 28, 2011.
I disconnected the oxygen sensor and the car still ran rough after warming up. Check engine light did not come on.

Tiny
Philmsherman
May 1, 2011.
If the sensors are bad, unplugging it wont help, If the computer does not see a bad or disconnected O2 sensor, check the connectors to the computer, and the fuses, check cigar lighter, ecm and IGN fuses under the hood and inside the car.

Merlin2021
May 1, 2011.
I checked the fuses and then checked the computer codes again and found code 13, oxygen sensor circuit. There were no bad fuses. I then checked the voltage output from the O2 sensor after warmup and it varied from 0.1 to 0.2 volts with a varied engine RPM. Should I replace the O2 Sensor next?

Tiny
Philmsherman
May 3, 2011.
Probably the left O2 sensor drivers side, but it wouldnt hurt to change em all.
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Merlin2021
May 4, 2011.
If computr were bad you would have many codes, not just the exact code you got.

Merlin2021
May 4, 2011.
I replaced O2 Sensor, erased codes, then engine started and ran good until warmup then again started running rough and losing power. I checked codes again and no codes were set. What should I try next? Any ideas are much appreciated.

Tiny
Philmsherman
May 5, 2011.
You may need to check the coolant sensor. And maybe the wires in the O2 circuits

Merlin2021
May 11, 2011.
I took it back to a mechanic that had been referred by a friend and he rechecked the injectors. He found three more faulty injectors that had low ohm readings after warming up. I had him replace all of the old injectors and the Vette is running like new.

Tiny
Philmsherman
May 25, 2011.
Thanks for letting us know the problem has been resolved.

Rivermikerat
Jun 25, 2011.

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