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is this normal when my iac is unplugged i dont get an engine code or light just trying to see if my ecm is bad causing my intermediat misfire thank you
 

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Mine doesn't get a code either when it is unplugged. IAC unplugged will just lower RPM a little from where the computer thinks it should be.
 

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is this normal when my iac is unplugged i dont get an engine code or light just trying to see if my ecm is bad causing my intermediat misfire thank you
IIRC the EEC doesn't monitor the IAC. It varies the duty cycle until the Idle is where the EEC wants it. It won't set a code if you unplug it, it just wont idle at the correct rpm.
 

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IIRC the EEC doesn't monitor the IAC. It varies the duty cycle until the Idle is where the EEC wants it. It won't set a code if you unplug it, it just wont idle at the correct rpm.
On my '94 with the IAC unplugged, I got two codes, 411 Unable to control idle - high, and 412 Unable to control idle - low.
This was when running the KOER test. During the KOER test, the PCM revs up the engine pretty high during the test, apparently if the PCM can't change the engine speed, it sets a code.
I didn't try driving the truck and see if it would set a code without running the test.

Try running the KOER test on your truck with the IAC unplugged, as apparently there is something different between the PCM programming on our two trucks. Maybe it has something to do with the MAF versus SD programming. My '94 is an SD 5.8.
 

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On my '94 with the IAC unplugged, I got two codes, 411 Unable to control idle - high, and 412 Unable to control idle - low.
This was when running the KOER test. During the KOER test, the PCM revs up the engine pretty high during the test, apparently if the PCM can't change the engine speed, it sets a code.
I didn't try driving the truck and see if it would set a code without running the test.

Try running the KOER test on your truck with the IAC unplugged, as apparently there is something different between the PCM programming on our two trucks.
That's only during the KOER test. It doesn't do it during normal operation.
 

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So, it looks like running the KOER will give the OP a code if his IAC is badly screwed up, if he doesn't want to run the KOER test to help diagnose the problem, then live with the problem and don't complain.
 
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