Everytime i start my 1981 corvette, it starts perfect, then the check engine light will come on, and the horsepower of the car is greatly affected. It stays on for about 15 minutes, then goes away. The car runs perfectly strong when the light is off. When its on the car completely boggs out, no power what so ever. Already changed the oxygen sensor and also a sensor in the carberator. Myself and 2 mechanics are baffled by this. Can anyone think of something? Email me at cheftel13@aol.com Thank you!
81' Check Engine, Horespower Failure
- Thread starter cheftl13
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bill81vette
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Did you pull the code out of the computer???
the hookup for the link is under the ashtray.
bill
the hookup for the link is under the ashtray.
bill
- Thread starter
- #3
About 81'
Hey, Bill, Yes, we hooked it up to the computer, 3 codes came up, we replaced all three parts that gave codes. ?????? Nice car by the way, mine is dark red metallic, with 52,000. Just tripped it on Sunday. If you can think of anything else, please let me know. Thanks
Mario
bill81vette said:Did you pull the code out of the computer???
the hookup for the link is under the ashtray.
bill
Hey, Bill, Yes, we hooked it up to the computer, 3 codes came up, we replaced all three parts that gave codes. ?????? Nice car by the way, mine is dark red metallic, with 52,000. Just tripped it on Sunday. If you can think of anything else, please let me know. Thanks
Mario
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I'm not sure, but don't you have to reset the computer to clear the codes? I believe you do this by just disconnecting the battery for about 15 minutes. I'm sure someone that knows for sure will chime in.
Mike
Mike
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Yes, you have to disconnect the battery for 15 minutes or so to erase the computer memory. Then it will learn the new settings with the new functioning sensors.
Several years ago we had about the same thing going on. It would start out running well then the check lite would come on and the engine would go into limp home mode, which is what you are experiencing. After the dealer working on it all summer, scanning, changing sensors, ECMs ect. with little success, they sent it down to Delco electronics in Kokomo IN. After all, if they made the stuff they could surely fix it, right. Wrong!
After 2 weeks they sent the car back declaring it cured. It ran home to the dealer where my wife works just fine. On her way home from work it lit the check engine light and went into limp home mode again.
Totally frustrated, the service manager ordered a NEW, now remanufactured, ECM and a new prom chip. When installed together the car ran great and has since for the last 15 years or so.
I'm not saying this is what you need to do but after numerous scans and sensor and ECM replacements this was about all that was left to do. There was no logical reason to do this based on diagnostic proceedures following the service manual to the letter, there just wasn't anything left that had not been tried at least once.
One more thing to look at. All of your connectors for the ECM and sensors are gold plated because they have to have a perfect connection for the very low voltage signals that pass through them. If any of the sensor plug boots are allowing any moisture in you are in trouble. The ECM and prom plus also need to be perfectly clean. Check them all carefully for any signs of corrosion or moisture.
Tom
Several years ago we had about the same thing going on. It would start out running well then the check lite would come on and the engine would go into limp home mode, which is what you are experiencing. After the dealer working on it all summer, scanning, changing sensors, ECMs ect. with little success, they sent it down to Delco electronics in Kokomo IN. After all, if they made the stuff they could surely fix it, right. Wrong!
After 2 weeks they sent the car back declaring it cured. It ran home to the dealer where my wife works just fine. On her way home from work it lit the check engine light and went into limp home mode again.
Totally frustrated, the service manager ordered a NEW, now remanufactured, ECM and a new prom chip. When installed together the car ran great and has since for the last 15 years or so.
I'm not saying this is what you need to do but after numerous scans and sensor and ECM replacements this was about all that was left to do. There was no logical reason to do this based on diagnostic proceedures following the service manual to the letter, there just wasn't anything left that had not been tried at least once.
One more thing to look at. All of your connectors for the ECM and sensors are gold plated because they have to have a perfect connection for the very low voltage signals that pass through them. If any of the sensor plug boots are allowing any moisture in you are in trouble. The ECM and prom plus also need to be perfectly clean. Check them all carefully for any signs of corrosion or moisture.
Tom
P
Pa Goose
Guest
My 81 did the same thing only the check engine light stayed on all the tiem and did not have enough power to pull itself 5 feet. The problem was with the temp sensor, it was telling the computer it was -18* when it was actually +85*. Richened out the fuel to the max.
Stingray6974
Well-known member
What codes are you getting?
Mike
Mike
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