1989 rough idle and engine light

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luigisho

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well let's see the codes. The ignition was really bad so who knows what the condition of most of the stuff is. Everything is past it's expected life cycle that was original and even any replacement parts put on long ago
 

rubydist

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sounds like a bad iac. I've had them bad (sticky) right out of the box, so even if its new that means nothing.


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the stuff its complaining about are all on the same power circuit from the pcm, so you could just have a bad wire in the harness or bad connector. I'd also look at the power and grounds to those sensors.
 

cali+Mocasho+

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sounds like a bad iac. I've had them bad (sticky) right out of the box, so even if its new that means nothing.


edit
the stuff its complaining about are all on the same power circuit from the pcm, so you could just have a bad wire in the harness or bad connector. I'd also look at the power and grounds to those sensors.
also i pulled the iac off of a 93atx. they were shaped a little bit differently. Im sure they both work about the same. right?
 

cali+Mocasho+

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i do believe i have a grounding issue somewhere. when the head lights are on,my temp gauge slightly goes up. mostly with the wipers on.
can you point me to a page for the location of every ground in the engine bay. ill clean everyone if i can.
 

luigisho

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There are videos on youtube on how to track down shorts and stuff if you want to poke around for ideas.
 

cali+Mocasho+

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Shit that a lot of grounds . I'll be busy for a while. Thank you 92sho.
I'm open to criticism and ideas.
 

rubydist

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you gotta ohm out the harness too - I've had opens in the looms.
 

cali+Mocasho+

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After cleaning the headlights grounds and the dis to firewall, pcmto battery and battery to firewall. ran codesand got
koeo- 22
Koer- 11 systems check fine
Pull the battery for 15 mi press brake to discharge remaing energy. Hook the battery back up and the damn light turns on almost instantly.
Now I starting to suspect the pcm. There was a hyperchip plugged into this thing for who knows how long. I obviously have had it out for a while now and don't plan to put it back in. Anyone think the chip fried it?
 

black92

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The chip itself may not have hurt the PCM, but improper installation or removal might? Try a known good PCM if you have one.
There is a ground in the valley of the engine. Its hard to access, but its there.
 

cali+Mocasho+

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The chip itself may not have hurt the PCM, but improper installation or removal might? Try a known good PCM if you have one.
There is a ground in the valley of the engine. Its hard to access, but its there.
Makes sense. I'll look for a pcm. Where exactly is the ground your talking about?And how important is it? When I got to it it was plugged in and the chip part was dangling. Was fairly easy to remove.
 

luigisho

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I never liked taking the plastic holding bracket off to use the chip. I like supporting it from the firewall and glovebox ends. Who knows if the chip contacts eventually have an effect or if only being supported on one end over a really long time has some small movement issues that manifest this far out. Hard to tell, as we are seeing more and more hard to pinpoint electrical issues where it used to be much easier to point to failing sensors and easy to access spark components.
 
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