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Discussion Starter #1
hi guys, let's make this story short.
I have 2002 Impala 3.4l 140K miles.
I noticed coolant leak and than replaced lower intake manifold gasket.
after work completion I took car for the ride and noticed higher rpm at idle ( like 950 instead of 700). I checked for vacuum leak but didn't find any. Few days later I found DTC 0507.
when do you start the engine the idle speed RPM still around 700 as supposts to. after you playing with accelerator pedal the RPM not coming back to normal and still around 950.
today I found even more interesting thing-I came to the work and parked my car. I checked rpm at idle speed and as last time it was high again. At this point I realized that fan working an in windshield position that making RPM higher at idle because in this fan direction a/c working. When I turned fan of I surprisingly found vehicle RPM.normal. I made a ride and it is returned to higher. Then I turned fan on to windshield position and stopped-RPM back to normal. Does it say I have faulty Idle Air Control valve or some different problem?
 

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Discussion Starter #3
Thank you. But only possible vacuum leak I found around 4th cylinder injector at upper intake.And it is not big. And if so, why the idle RPM when I staring engine still O'k, plus after I turning of a/c or windshield directed hvac RPM coming down to normal?
 

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OEM LOL
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3,804 Posts
With you jusy disassembling and reassembling the motor. Its more likely that you forgot to put something on or put it on wrong or pinched something causing a leak.

A/c should raise idle because it takes more juice to run the ac compressor.
 

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Discussion Starter #5
Ok. My question is why I still get right RPM when I starting engine (not like you turning it off and then on) and after I using a/c. By the way, when I have higher RPM and turning a/c the RPM coming even down from 950 to 830-850 and when I turning a/c off RPM slowing down to normal 700.
 

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Mr. Handy
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6,289 Posts
Likely IAC. Check all connections and wiring for the IAC. If nothing looks fishy, replace IAC and check for a change.
 
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