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Discussion Starter #1
Sometimes after the car is up to operatring temps and shut the motor off then restart it latter the motor still at operating temp it will rev to 3500 to 4500 RPM's then go down to 1000 RPM after a couple seconds WHY.



I dont have any vacume leaks the base Idle is set at 450 RPM's the Normal timiming set a 6 advance.



Most of the time in gear the Idle is at 650 to 700 RPM In gear it's a uto trans.



The motor not stock it a mild build it has a chip for the mods.



I dont remember the motor doing this before the rebuild from stock motor.



It will also surge when slowing down moving foward to a idle 650/700 Rpm's to 1000 Rpm's I think it's the TQ convertor the place that rebuild the trans screwed it up I still working getting anouther trans.
 

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Discussion Starter #3

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Don't care what you set the idle at. What is the command idle from the ECM? Also, did you clean the throttle body? Remove it and clean the whole thing including the IAC housing. Take that out too and clean ALL passages.

After that, get a scanner on it and tell us what the command idle is and the IAC counts will all accessories off
 

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Check the routing on your throttle cable as well....I had the same issue after my bottom end work and they routed the cable over everything instead of under the radiator hose. :(
 

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Just like the above guy said.... whats the ecm commanding? I had a s-10 blazer that would do exactly what yours is doing....every year.

I had to remove the iac an clean its pintle off and the area in the tb the pinte went down in. It would get carboned up pretty bad. Same with the EGR valve too. I just used a can of brake parts cleaner to do the job. The carbon just turns to a liquid sludge when that brake parts cleaner hits it.
 

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Discussion Starter #7
Every thing was cleaned out and up during the rebuild it has about 1500 mile on it now.

New IAC valve I checked all the cables reset hte voltage from .55 to .54 Put the stock M<AF back on itseem to run better today and not have such a high Idle at hot and warm starts now.

I getting all the bugs worked just taking time to hunt them down.
 

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Every thing was cleaned out and up during the rebuild it has about 1500 mile on it now.
Did you set the min idle when you put in the new chip and IAC valve?
 

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Discussion Starter #9

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Discussion Starter #11

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Discussion Starter #12
Base Idle set at 450 RPM's.
 

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Discussion Starter #13
Adjusted the TPS to .539 Volts it was at .55

Put the old Spare MAF back on It runs great now.
 
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