Need some help

[Thomas F.]

1984 Corvette, starts fine, runs good, until I stop engine after it has reached operating temperature. After a period of time maybe 1 hour or less engine starts fine but does not want to accelerate without stumbling and hesitation for a few minutes then it returns to normal operation and runs fine. Fan is working normally. Could this be a heat soak issue?

[Edward J.]

Re: Need some help

Tom, do you have a scan tool to check the coolant temp sensor and see how the temp. registers on the scan tool when the problem arises? Check for trouble codes. The old coolant temp sensor connectors of this era tend to fall apart with age and a poor connection with these style connectors will cause poor starts( because the sensor can go open). another thing is to make sure the coolant temp sensor is not weeping anti freeze up through the plastic housing of the sensor it self,this will migrate to the computer through the wire, and then its good by computer.

[Thomas F.]

Re: Need some help

Thanks Edward for your reply. Are you talking about the coolant temp sensor switch that controls the electric fan? If so I recently purchased a new sensor switch that will turn on my cars fan at a lower temp but I have not installed it yet. I think the factory setting is 228 degrees and the one I purchased is 190 degrees. I hope this will not have any effect on the operation of the ECM. I am not having any trouble starting the car, it starts fine hot or cold, but after a hot start is does not want to run properly for several minutes. I cannot pull out normally in the car until the motor has run very poorly for a few minutes then it starts running normally. I can drive the car very slowly but not in any traffic until if finally decides it is ready to run normally. When I start the car cold I can drive off immediately without any problems. I will check for trouble codes and consider purchasing one of those heat scan tools. I am sure it would come in handy. Thanks again for your help Looks like you have some nice rides. I also have a 69 BB Convertible I play around with. Have a nice day.

[Edward J.]

Re: Need some help

Tom, I am sorry forgetting that there are about 3 temp sensors on your car, But the one I am speaking of is the one the computer looks at for making air/fuel calibrations(two wires yellow and black). What can sometimes happen with this sensor it can heat up and will sometimes hit a spot on the rheostat that is internal of the sensor and go open. this will sometimes fool the computer to think its starting a cold/cool engine or even the opposite can happen. Those cross fire injection engines run very rich on cold starts, and what happens when the car start up hot with a sensor that reading a engine is cold? hard start long crank time. Hope this makes sense to you. a scan tool for the engine computer is really a helpful tool and helps make the dia. easier. Go on ebay and look for a inexpensive scan tool that can read OBD1 cars, most of the newer ones do both OBD1 AND OBD 2(96 and newer) make sure it has al the connectors for both generations.

[Thomas F.]

Re: Need some help

Edward, thanks again for this information. I really appreciate your feedback and will take this into consideration. I don't work too fast and it may take me a long time to check this out. Have a nice day.