The check engine soon light comes on at high speed driving. Once I stop the car and shut the engine off, the light stays out when restarted. At time the light comes on under heavy acceleration. The car had the main computer, IAC, TPS, AND INTAKE AIR TEMP UNITS replaced due to an uncontrollable idle. The engine would idle at 3 to 4k. It went back to normal parameters after changing the TPS, and adjusting the IAC. I get very poor gasmilage probably around 13 in the city. Used to get 27 on long trips, now about 15. The computer is pretty useless since very shop I take it to I am told the computer can not pin point a problem, with only a general area being considered. In other words, the computer is better used for a boat anchor.
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1994 Chevrolet Camaro Question: Check engine light
Answer #1mastertech6371 December 01, 2010, 21:10Master
wow, you got some bad advise.
first of all, what were the code numbers for the failure?
did anybody think of checking the o2 sensor?? real common failure for the light, as you described, and the poor mileage.
the tps adjustment tricked the computer to slow down the idle but did not fix the issue.
there is no adjustment for the iac. just a tool that runs it in and out to make sure the idle moves up and down. the computer controls the setting.
without the computer, no engine operation at all. you need a new shop that has a more mature tech familiar with obd1 systems.