89cheyenne

I’ve been driving the same ’89 Chevrolet Cheyenne as my every-day work truck for the past ten years. Over the years I’ve rebuilt the engine and done all the required maintenance and it’s remained essentially stock except for removing the catalytic converter and blocking off the EGR. It is 305 cubic inch, 5-speed manual, throttle body injection and computer controlled with ODB1.<O</O
In the last year or so I can not get it to idle once it’s warm. The truck starts great and will idle for hours as long as I don’t drive it. As soon as I drive it, the engine will not return to idle but will stall. Very rarely, the engine will return to a good idle and will not stall. No trouble codes except for code 32 which is EGR.<O</O
I put in a new idle air control (IAC). I’ve also recently installed new TPS and MAP sensors, PCV, fuel filter and alternator. All parts are from Napa. Timing is TDC as per the emissions label. I’ve read through the “rough, unstable, or incorrect idle, stalling” section in the factory service manual probably 45 times. This one is driving me crazy…PLEASE HELP.<O</O
Thanks very much!!!<O</O

tinbender59

go to the EGR valve, reach under it and push the diaphram up. you will be able to get to it through the "frame" of the EGR. if it sticks? or is hard to move? or if it is stuck up even? you have found the culprit. sounds like it to me like it is sticking anyway. buy a block off plate, or build one like I did.

1988scotdale

my two cents

The coolant temp sensor? Read the sequence of operation for the computer ECM.