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Discussion Starter #1 (Edited)
have a 2nd hand 92 chevy 1500 (145,000 miles) with 350 engine and throttlebody and it is currently on its 3rd OBD1.

owned this truck for a year but seldom driven until the past few months. It started having severe loss of power but it was intermittant........might travel 50 miles and it runs like a top. Next 10 miles its running like some cylinders are not getting proper spark/fire. Strong odor of fuel when it does this. It will suddenly correct itself and run good for a while and then just as suddenly it will run rough.......very sudden changes with no warning.... like in flipping a light switch sudden.

A mechanic friend has a hand computer and put it on it and it did not "throw any codes". The catalyitic converter was replaced, and he also replaced the distributor and coil (?)...says the fuel pump is fine.....still gave same problems. Finally he removed the glove box and found the computer box and it was almost too hot to handle. He replaced the computer with one from autozone. Truck ran very well (like a new one) for about 1200 miles and it started acting up again with the same symptoms. Felt like i barely made it home as it seemed to run awful rich with little spark..... not showing any codes on his hand computer, not even a check engine light.

Pulled that OBD1 computer and replaced it under warranty with another and the truck ran great again but only for about 400 miles.......then it started acting up again. We've tried un-pluging and re-pluging the computer but no change.

truck seems to be running ok at the moment (past 40 miles), but ever so noticable it gets rough again for just a second or two. i do not trust it to go out of town or to tow the small boat to the local lake to fish.....which is killing me right now.

we don't have a clue and this is a poor boy operation.......any ideas?

i thought if the obd was fried nothing would work..........why just effecting the spark/timeing??

did i buy somebody else's troubles?




 

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Since replacing the ECU seems to fix this for a while, I'm thinking you might have a bad connector(s) or a loose one right at the plug. Each time you unplug it & install a new ECU the connector(s) get a new contact, but it seems like it is losing contact intermittantly over time. Pop the plug off the ECU & look at all the connectors to see if they all appear the same. Also pull on each individual wire (one wire at a time, a real PITA, but if you don't do them one wire at a time you might never find the bad one) & make sure that they are secured in the plug.
If one of the connector detents is not holding a wire(s) securely in the plug, then when you plug it in that wire(s) never goes completely in & doesn't get secured & instead gets pushed partially back into the plug housing making poor contact & eventually works loose.
 

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Discussion Starter #3
appreciate it.......will try to check out the wiring.........

also read the sticky about the testing for codes on a OBD1 the old fashion way without a hand computer. might also try that as i am still wondering why the thing will not thro codes on his machine.

just have to pay close attention to the engine light and see what it tells me.....if anything.
 

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Discussion Starter #4
what are some of the things to look for that will make an OBD1 computer suddenly go into fail-safe or "limp home" mode?
 
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