1981 Check Engine Light Runs Rough

[WONKABOY]

I Pick Up A 1981 Last Week , When You First Start It Up It Runs Fine , High Idle , Kick Down , And I Nice Idle At A Stop Sign, As You Drive It For A Very Short While And You Come To A Stop Sign It Runs Like It's Going To Stall Very Low Idle Then You See The Check Engine Light Appear , The Cars Accelaration Is Smooth As Can Be No Matter How The Idle Is, Just Today I Was Out For A Long Drive And This Time I'm Slowing For The Traffic Light And It Was Ready To Stall , It Seems It Has Gotten Worse It Has Plenty Of Gas In It So I Know It Wasn't That , Did Anybody Out There In 81 Land Ever Had This Happen And What Was The Fix? Thanks Rick

 

[SpartanSith]

well mine does this for a minute or two, if i dont warm it up, but is fine after that, it also usto drop out until i replaced the fuel pump...

hope this helps,
SpartanSith

 

[gsimpson9981]

a bad EGR can cause a rough/stall after deceleration.

 

[WONKABOY]

Thank You

 

[WONKABOY]

a bad EGR can cause a rough/stall after deceleration.

THANK YOU

 

[Vader]

Your "CHECK ENGINE" light is trying to tell you something. All you need to do is listen. The stored error code(s) may help you find the source of the problem(s).

The ALDL connector is under the center console ash tray. Shorting the leftmost two pins invokes Field Service Mode. WITHOUT STARTING the engine, turn the ignition to the "RUN" position. Watch the Malfunction Indicator Lamp (MIL) - it will begin to flash. This is also commonly called the "Service Engine Soon", "Check Engine", or "SES" lamp. The first code will flash three times, and will usually be a code "12". You'll always get a "12", since the ignition is on and the distributor is not turning (no reference pulses being generated). This is encoded by one flash of the lamp, a brief pause, then two successive flashes of the lamp. Each code will repeat three times, so you should see a code "12" flash three times. Any other stored error codes will follow in numerical order, and each code should flash three times. After all codes have been displayed three times, the "Code 12" will again flash three times, then all other codes will follow as described earlier. This cycle will continue until the jumper is removed or the ignition is turned off.

After you have made a note of all error codes, turn off the ignition and remove the jumper immediately. If you forget to remove the jumper and attempt to start the engine with it in place, you could damage the ECM. For this reason you should remove it immediately.


Code #12: No Distributor Reference Pulse.
Code #13: Oxygen Sensor Circuit.
Code #14: Shorted Coolant Sensor Circuit.
Code #15: Open Coolant Sensor Circuit.
Code #21: Throttle Position Sensor Circuit.
Code #23: Mixture Control Solenoid Circuit.
Code #24: Vehicle Speed Sensor Circuit:
Code #32: Baro Sensor Circuit Low.
Code #34: Vacuum Map Sensor Circuit.
Code #42: EST Failure
Code #44: Oxygen Sensor Lean.
Code #45: Oxygen Sensor Rich.
Code #51: Faulty or Mis-Installed PROM
Code #52: Faulty ECM.
Code #53: Faulty ECM.
Code #54: Shorted Mixture Control Solenoid.
Code #55: Faulty Oxygen Sensor or ECM.

 

[WONKABOY]

Thank You For The Info, I Made An Appointment For Friday Morning With A Local Fella Who Owns A Repair Shop But Also Drag Races Chevys For A Living , He Says He Knows About All The Codes , Told Me To Bring It Down, I Know For Sure That That Carb Runs Fine From Take Off Smooth As A Wistle, But Coming To A Stop Sign She's Shaking From A Low Idle And Ready To Stall , This Happens About 3 Mins After I Take Off From A Overnite Startup, It Has The Idle At The Stops And Seems Great No Shake , But That Does Not Last To Long

Thanks For The Feedback

 

[jdp6000]

Sounds familiar. My guess is low fuel pressure. Does the 81 have an intank electronic fuel pump? I think it does.

Jim

 

[gedmeyer]

Sounds familiar. My guess is low fuel pressure. Does the 81 have an intank electronic fuel pump? I think it does.

Jim

Nope, mechanical pump on the block.

 

[WONKABOY]

Thank You

 

[WONKABOY]

a bad EGR can cause a rough/stall after deceleration.

THANKS

 

[WONKABOY]

Nope, mechanical pump on the block.

THANK YOU

 

[smithjw]

Sounds like a problem I once had. It was the fuel pump. Replaced it and all was well again.

 

[Ol'Scratch]

Rough Idle

Hi Fellas!!...
This sounds like mine in reverse. Mine idles real rough when you first start it...then smooths out when as she warms up. I think someone once mentioned that it sounded like I had a vacuum leak. But I've haven't found it yet.

 

[jdp6000]

Sounds choke related. Or...81 has a computer right? Common cause of your problem on an 82 is the CTS going bad. Check and see if you have a Coolant Temp Sensor. Should be at the front of the intake below the place where your thermostat is.

Jim

 

[WONKABOY]

a bad EGR can cause a rough/stall after deceleration.

THANKS! RICK

 

[WONKABOY]

Your "CHECK ENGINE" light is trying to tell you something. All you need to do is listen. The stored error code(s) may help you find the source of the problem(s).

The ALDL connector is under the center console ash tray. Shorting the leftmost two pins invokes Field Service Mode. WITHOUT STARTING the engine, turn the ignition to the "RUN" position. Watch the Malfunction Indicator Lamp (MIL) - it will begin to flash. This is also commonly called the "Service Engine Soon", "Check Engine", or "SES" lamp. The first code will flash three times, and will usually be a code "12". You'll always get a "12", since the ignition is on and the distributor is not turning (no reference pulses being generated). This is encoded by one flash of the lamp, a brief pause, then two successive flashes of the lamp. Each code will repeat three times, so you should see a code "12" flash three times. Any other stored error codes will follow in numerical order, and each code should flash three times. After all codes have been displayed three times, the "Code 12" will again flash three times, then all other codes will follow as described earlier. This cycle will continue until the jumper is removed or the ignition is turned off.

After you have made a note of all error codes, turn off the ignition and remove the jumper immediately. If you forget to remove the jumper and attempt to start the engine with it in place, you could damage the ECM. For this reason you should remove it immediately.


Code #12: No Distributor Reference Pulse.
Code #13: Oxygen Sensor Circuit.
Code #14: Shorted Coolant Sensor Circuit.
Code #15: Open Coolant Sensor Circuit.
Code #21: Throttle Position Sensor Circuit.
Code #23: Mixture Control Solenoid Circuit.
Code #24: Vehicle Speed Sensor Circuit:
Code #32: Baro Sensor Circuit Low.
Code #34: Vacuum Map Sensor Circuit.
Code #42: EST Failure
Code #44: Oxygen Sensor Lean.
Code #45: Oxygen Sensor Rich.
Code #51: Faulty or Mis-Installed PROM
Code #52: Faulty ECM.
Code #53: Faulty ECM.
Code #54: Shorted Mixture Control Solenoid.
Code #55: Faulty Oxygen Sensor or ECM.

Thanks for the info!!!!! Rick

 

[Sensei]

The problem could be as simple as the idle screw adjustment! When cold, the fast idle cam raises the idle speed. Once warm, it is the idle screw and if it is too low (about to stall), the check engine light will flicker. But EGR is also a good guess. Good luck and God bless, Cris