Evilcowboy420
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Well I have apparently learned a lot about the ECM and electrical system in this car since owning it. I figured I would share in the event someone else has any problems with their car. Most drive ability problems and issues with these cars can almost always be traced to an electrical component failure. So here are a few quirky things and the problem they cause.
1. Stalling/Surging Idle (Hot) - Replace IAC Valve, also could be a TPS.
2. Thumping/Bucking on slow acceleration uphill - Replace ICM, Rotor, or Ignition Coil.
3. Stalling/Hard start (Cold) - Replace IAT Sensor
These are just a few of the issues these cars can have if a sensor or electrical part fails. The ECM in these cars are actually pretty smart and will let you know when a failure happens by acting quirky.
Below is what code will be thrown when some of the electrical components fail.
TPS - Code 22 will always be thrown. This is either the fuel cut off relay or the TPS. Most likely the TPS.
IAT - When failure occurs no code will be thrown. The only indicator it isn't working is hard starting car. The reason no code is thrown is it when it fails usually it will read as a -40 c. This tells the computer it's working but its just really cold. The car will dump gas to the intake to compensate and flood the engine.
IAC - Another No code. When these fail they still kind of work. This has been observed on my own car with 4 different ones. 3 used factory ones and finally a brand new replacement. The pintle moves in and out as it should but will be unable to dial in a setting. I was told by GM themselves they were junk back then and commonly failed. My guess is the pintle gets stuck mostly out and can't return to a 0. When this happens most people would try to compensate by adjusting the base idle screw. This will work but will cause the car to be in clear flood mode due to the non adjustable TPS reading much higher causing a very lean running car.
ICM - No Code either quits or timing will act out of sorts. ie. thumping under load or bucking.
CTS - This should throw a code either 14 or 15. Best to replace anytime you replace a thermostat.
O2 sensor - 44 or 45 is what it commonly throws. Not much noticeably changes but if it is original then its bad by now.
This is by no way a complete list of electrical issues with this car but it is a list of what I have seen most commonly complained of when it starts acting funny. ie. intermittent drive ability issues.
These cars were reliable cars in their day but are also one of the most neglected cars due to the low cost and cheap parts it is made from. The engine is notorious for oil leaks. Especially the seal between the tranny and engine, the gasket between those as well, Crank seal, cam seal, ATF pan, Oil pan (thin metal and will almost certainly warp trying to remove it), drain plug gasket, head gasket, cam carrier gasket, freeze plugs and water outlet gasket.
I will say once all unnecessary parts are removed from the engine to make more room it is quite a fun engine to work on.
Anyway good luck to anyone trying to figure drive ability issues on these cars. But of them all that will stump most is the surging and rough idle. Save a ton of head ache and just replace the IAC with a new one. It will save you quite a large hunt.
1. Stalling/Surging Idle (Hot) - Replace IAC Valve, also could be a TPS.
2. Thumping/Bucking on slow acceleration uphill - Replace ICM, Rotor, or Ignition Coil.
3. Stalling/Hard start (Cold) - Replace IAT Sensor
These are just a few of the issues these cars can have if a sensor or electrical part fails. The ECM in these cars are actually pretty smart and will let you know when a failure happens by acting quirky.
Below is what code will be thrown when some of the electrical components fail.
TPS - Code 22 will always be thrown. This is either the fuel cut off relay or the TPS. Most likely the TPS.
IAT - When failure occurs no code will be thrown. The only indicator it isn't working is hard starting car. The reason no code is thrown is it when it fails usually it will read as a -40 c. This tells the computer it's working but its just really cold. The car will dump gas to the intake to compensate and flood the engine.
IAC - Another No code. When these fail they still kind of work. This has been observed on my own car with 4 different ones. 3 used factory ones and finally a brand new replacement. The pintle moves in and out as it should but will be unable to dial in a setting. I was told by GM themselves they were junk back then and commonly failed. My guess is the pintle gets stuck mostly out and can't return to a 0. When this happens most people would try to compensate by adjusting the base idle screw. This will work but will cause the car to be in clear flood mode due to the non adjustable TPS reading much higher causing a very lean running car.
ICM - No Code either quits or timing will act out of sorts. ie. thumping under load or bucking.
CTS - This should throw a code either 14 or 15. Best to replace anytime you replace a thermostat.
O2 sensor - 44 or 45 is what it commonly throws. Not much noticeably changes but if it is original then its bad by now.
This is by no way a complete list of electrical issues with this car but it is a list of what I have seen most commonly complained of when it starts acting funny. ie. intermittent drive ability issues.
These cars were reliable cars in their day but are also one of the most neglected cars due to the low cost and cheap parts it is made from. The engine is notorious for oil leaks. Especially the seal between the tranny and engine, the gasket between those as well, Crank seal, cam seal, ATF pan, Oil pan (thin metal and will almost certainly warp trying to remove it), drain plug gasket, head gasket, cam carrier gasket, freeze plugs and water outlet gasket.
I will say once all unnecessary parts are removed from the engine to make more room it is quite a fun engine to work on.
Anyway good luck to anyone trying to figure drive ability issues on these cars. But of them all that will stump most is the surging and rough idle. Save a ton of head ache and just replace the IAC with a new one. It will save you quite a large hunt.