Chevrolet Repair: 92 Lumina Speedometer, gas fumes, hi bob

Question
Hi Mark,

My daughter has a 92 Lumina, 3.1, which will drive fine, no problems, suddenly the speedometer will shoot up and go crazy. If she comes to a stop while this is occuring, the engine will stall. She says that she smell gas fumes.  She has taken it to a shop twice and they replaced three sensors which included the speed sensor, idle sensor, and she was not sure what the other sensor was.  She was told that the diagnostic machine says that all is working fine after these replacements. But the problem continues. Now the shop told her that they do not know what is wrong. Any help is appreciated.

Answer
Hi Bob, I hate when they just throw parts at something and have no clue what might be the problem. This gives me a bad name!! You need to replace the ECM (computer) and this will solve the problem. After replacing the ecm the idle will have to be relearned. To do this you run the car in drive at normal operating temp at a stop for 10 minutes. Then you turn the engine off for a minute and then run it again in drive for 5 minutes. This will reset the ecm so it knows where to control the idle.

Have a Great Holiday

Mark