Well here is the sad story...I let my sister borrow my car and she said she thought she was running out of gas. It puttered its way to the gas station. well after that its been running like garbage.(ses light started coming on so i figured off to the mechenic). I went to start it and my luck the key wouldn't turn to crank. so it got towed. So a new ignition was put in. The prob with the fuel i figured it was the pump. the mechenic said the pump was putting out 38 pounds preasure. he could not get any codes out of the ecm so he put in a new one. Well of course still no codes so he said it was my hypertech prom..well wrong again. Now after new coil, new wires,plugs. i took my car back and said no thanks i can guess too. here is the thing, the ses goes on and off when its on it runs like a champ but has bad idle,when light is off great idle but no throttle response. any Ideas?? btw 350 tpi, flowmaster exaust , superflow cat, 60,000 miles

 

Need the codes to troubleshoot. It's probably going into open loop when the light is on.

 

Being that it is an '89, I'd say either the MAF or the ECM. With it running great when the SES is on, I'd guess MAF sensor. When the ECM thinks the MAF is bad it creates an airflow value from the engine RPM & throttle position.

To help trouble shoot: with the engine running SES off, tap on the MAF sensor. If the engine stumbles either the MAF is bad or the connectors are bad. Another tip: unplug the MAF and see if the engine is now OK. You can drive it a bit like that for an extended test.

If it continues to run OK with the MAF unplugged, again, MAF oe connectors.

Can do the same tap test on the ECM.

Of course, it could also be another sensor such as the TPS or CTS. Just need to check each to see what is going on.

RBob.

 

Thanks Very much I will try those ideas today!!