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Discussion Starter #1
Though it may be self exploratory, need some help with this code. Car is bone stock 5.0 with a CAI setup. Been having some idle issues lately. Where should I start with this?

12 - RPM Not Within Self Test Upper Limit (R),
Idle Speed Control motor or Air Bypass not
controlling idle properly -generally idle too low
 

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Sounds like you need to remove the IAC and clean it with some carb cleaner for starters. See if that cures the problem before you buy a new one. You can also test the pigtail that hooks to it to see if it's getting voltage.
 

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If the throttle body is dirty, and Idle falls to low, this code can show. Do as MSally suggested and clean IAC, and Throttle Body.....
 

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Discussion Starter #4
Thanks for input guys. I've actually done a bit.

I adjusted the tps sensor to .84 volts, is this too low?
Bought a new ect sensor since I got a code for that, and mine was old anyway.
I did spray the whole inside of my TB and it seemed to run a bit smoother. But as I was sitting at a light, car started idleing funny again.

I'll go clean IAC sensor now and also I'll report any voltages it gives me.
 

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If you can't get it around the 0.98 Volts range you might need to remove the TPS and drill out the holes just a hair.
 

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Discussion Starter #6
Alright update.

Cleaned the IAC, wasn't really all that dirty. Also with KOEO I got a solid 12.4v going into the IAC.
I adjusted my TPS to .98

Car still has a extremly rough 500-700 idle. If I give it gas it runs fine. Only at idle.

However. While running, I unplugged my MAF and car seemed to clear out a bit. I cleaned up the MAF contacts without breaking them, installed it and same thing. I'm pretty much lost at this point. I did this cause of my k&n air filter.

Over the past few weeks to a month, upon cold start, the car idles like it has an aggressive cam. Which it doesn't.
 

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You need to do a base idle reset. Do a search for Summarized Base Idle Procedure.

Does the engine stall with the IAC unplugged?
 

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Discussion Starter #8
You need to do a base idle reset. Do a search for Summarized Base Idle Procedure.

Does the engine stall with the IAC unplugged?
I just looked it up and I'm in the process of doing it now.

I've unhooked the IAC a few times. The handful of times I've unplugged it the car never stalled. Didn't even really change idle either. I did it twice today and the engine did stall. But did it again and nothing happened.
 

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Discussion Starter #9
Did the idle reset and got it up to about 1k rpms. I couldn't get it to idle right with anything below 1k
Upon setting the tps, I couldn't get it lower than 1.03 volts. Did I set the idle too high? Do I need a new tps module, or should I just drill out the holes?
 

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Idle needs to be set with the IAC unhooked and at an Idle Point just low enough that the engine doesn't stall. I usually shoot for 650 or so RPM, so when the IAC is plugged back up, the idle shoots up to 725 or so RPMs. Some engines like it a little higher. After all the Idle fiddling is done. Make sure the TPS voltage is within range. 1000rpms is way to high. Shoot for 750-800

Then rerun the codes....
 

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Discussion Starter #11
Idle needs to be set with the IAC unhooked and at an Idle Point just low enough that the engine doesn't stall. I usually shoot for 650 or so RPM, so when the IAC is plugged back up, the idle shoots up to 725 or so RPMs. Some engines like it a little higher. After all the Idle fiddling is done. Make sure the TPS voltage is within range. 1000rpms is way to high. Shoot for 750-800

Then rerun the codes....
I was afraid 1k would be too high. I will reset the idle and hopefully bring it down without it being unbearable. I also made another thread with 3 other KOER codes so I wouldn't clutter this one.
 
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