Bouncing Idle

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SolLess16

Senior Member
I just helped a friend turbo his z6 , everything went good except he has a bouncing idle from 1500 to 3000. He is running stock injectors and tuned with a vafc2 - any ideas on why its doin this?? im guessing the vacuum lines but everything looked alright - any help is apreciated thanks --- also he is throwing no codes
 
hey, I have a 94 Sol with the stock b16 and I had the same problem. My car would jump from about 900 rpm up to about 1300 whenever it was warmed up and idling. I had it at the dealer 4 times and they couldnt figure it out. I replaced the map sensor, IACV, 2 coolant sensors, and had the idle screw adjusted. Finally the dealer adjusted the idle all the way to its lowest setting which corrected the problem. The vacuum lines were checked repeatedly and no leakes could be found. I am not sure how to adjust the idle myself, but I would recommend trying this approach, its cheap and it worked for me with no ill side affects so far. Good luck!
 
are you throwing a check engine light? if not, getting the air bubbles out of the coolant is a good possibility - air bubbles in the coolant will affect the iac valve (on back of intake mainfold) this valve is activated by the coolant temp and adjusts idle accordingly - or you have a bad iac valve... not a cheap part either
 
coolant air bubbles
vacuum leak

these are the two i've seen cause this

i had a major vacuum leak (read: intake manifold gasket) which caused this, but something very minor could have the same results

adjusting the idle all the way down should not be the solution
 
Thanks guys , ill try bleeding the air out tomorrow when i get a chance - thanks again and any other advice is apreciated
 
well replaced the IACV , flushed and refilled the coolant, checked all vacuum lines- and still a bouncing idle - any way that it could be a TPS or anything?? any help is apreciated - thanks
 
also tried adjusting the idle on the front of the throttle body which did nothing - anywhere else i can try adjusting??
 
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