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89 Corvette Runs Rough

Tiny
PHILMSHERMAN
  • MEMBER
  • 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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Thursday, April 28th, 2011 AT 3:34 AM

10 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
After ecm goes into closed loop the o2 sensors come online check them first
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Thursday, April 28th, 2011 AT 10:24 AM
Tiny
PHILMSHERMAN
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  • 5 POSTS
I disconnected the oxygen sensor and the car still ran rough after warming up. Check engine light did not come on.
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Sunday, May 1st, 2011 AT 10:09 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
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.
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Sunday, May 1st, 2011 AT 1:22 PM
Tiny
PHILMSHERMAN
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  • 5 POSTS
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?
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-1
Tuesday, May 3rd, 2011 AT 4:06 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Probably the left O2 sensor drivers side, but it wouldnt hurt to change em all.
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Wednesday, May 4th, 2011 AT 7:53 AM
Tiny
MERLIN2021
  • MECHANIC
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If computr were bad you would have many codes, not just the exact code you got.
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Wednesday, May 4th, 2011 AT 7:54 AM
Tiny
PHILMSHERMAN
  • MEMBER
  • 5 POSTS
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.
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Thursday, May 5th, 2011 AT 2:58 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
You may need to check the coolant sensor. And maybe the wires in the O2 circuits
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Wednesday, May 11th, 2011 AT 3:46 PM
Tiny
PHILMSHERMAN
  • MEMBER
  • 5 POSTS
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.
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Wednesday, May 25th, 2011 AT 7:37 PM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Thanks for letting us know the problem has been resolved.
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Saturday, June 25th, 2011 AT 9:54 PM

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