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2005 Chevrolet TrailBlazer LS 4.2 I6, 155,000 Mi
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Hey all. This past Saturday (11/23/19) I finally decided to go ahead and clean the TB on my 2005 4.2 I6 with ~155k miles. After cleaning it with CRC Throttle Body & Intake Cleaner, I reinstalled it, removed fuses #10 and #28 for 15 minutes as MAY03LT on YouTube mentioned in his video on cleaning the TB. Then I went ahead and started her up, and the RPM went up to around 1500, then came back down around 1000. Took it for a drive, seemed to drive way better than before (still does), but i've noticed when I turn on the Defrost or A/C (I am aware that defrost uses the Compressor) it flares up to between 1200-1500 then comes back down to ~900. If I turn the A/C on instead, every time the compressor kicks on, it bogs down to about 500 and flares up to around the same RPM as with defrost on, but every time it kicks on. Cold starting has come down from 1500-1600 to around 1300 on initial startup. Is this normal for post-TB cleaning and PCM reset? If so, approximately how long should it take for it to straighten out, and would it help to always have one of them on while driving, even if it's not needed, to help it learn? I am new to all this relearn procedure stuff, so I apologize if this post is all over the place.
 

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Gonna go out on a limb here because this is the internet and your vehicle isn't here by me ---- but I've seen this problem when someone gets a little too much throttle body cleaner in the ISC.

ISCs can be damaged by the solvents in those cleaners. Did you position the throttle body in such a way to keep the cleaner out of the ISC?

If this part fails or becomes weak the engine idle speed could become erratic/too low/too high and this condition may or may not trigger the CEL.

Because of the nature of this valve (large air volume processed) it should be serviced to remove "coking" which will hinder the valve's low speeed or idle performance.

During this 'servicing' you must make sure to not get any cleaners inside the motor itself, by holding it so that any liquid runoff flows away from the motor itself.

To perform a rough check of the idle air control, remove the valve while reconnecting the wiring harness. While observing the valve with a flashlight, turn the key to the "ON" position, (DO NOT START ENGINE.) the valve should move slightly.

This test may set the CEL and you'll have to erase the code it sets.
 
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