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in depth idle issue.

4doorboost

Well-known member
Joined
Aug 19, 2008
Messages
208
Location
Westlake Village, Cali
so i have been searching for hours and i just wanted to get some input. i have a forged bottom end, hks 264 272 cams big16g all supposrting mods, ie injector front mount ec.. at idle i am having two issues. my car reads low vac(between 10-12) and it almost seems like i get a slight miss sometimes. the rpms move from about 750-710 ish but its not surging just seems like its not smooth. i have already changed my plugs wires, tried to find boost leaks. i was going to replace the o2 sensor tonight as its been a few years, and check to make sure i didnt skip a tooth on my timing belt. the car runs smooth at all other rpms(no misses) but my turbo does spool unusually slow. im goig to hook up a logger tonight so i should be able to post some logs tomorrow, but just wanted to see if anyone else if haveing any similar issues. any help appreciate
thanks
 

AnotherNewb

Well-known member
Joined
Apr 25, 2010
Messages
1,472
Location
Orlando, FL
What are you using for tuning? Your vacuum does seem a little low but if you don't have any boost leaks I would recheck your base timing. Also altitude will effect vacuum at idle.
 

4doorboost

Well-known member
Joined
Aug 19, 2008
Messages
208
Location
Westlake Village, Cali
unfortunately an safc, im saving up for dsm link. i put a new o2 in last night and it raised the idle a little bt it is smoother and it raised the idle to around 900.. i was also wondering. when the car is warm and you unplug the isc what is supposed to happen?
 

4doorboost

Well-known member
Joined
Aug 19, 2008
Messages
208
Location
Westlake Village, Cali
so after my ecu (re learned) i reset it, the idle dropped back to around 700. the thing is is hunts a little. it doesnt surge. it hunts from about 700 to a little over 800. its doesnt just go up and doen like surge its kinda random like its trying to find its idle. changing the biss doesnt change anything and neither does unplugging the isc. could the isc be bad?
 

socalgvr4

Well-known member
Joined
Sep 19, 2007
Messages
294
Location
Hillsboro Oregon, USA
Re check for boost leaks with a boost leak tester and soap and water across the ENTIRE system, including near the throttle body and intercooler setup. Id also check for intake manifold leaks. Start there.

Then are you sure the timing is set properly?
 

4doorboost

Well-known member
Joined
Aug 19, 2008
Messages
208
Location
Westlake Village, Cali
Ive replaced the throttle body gaskets intake manifold gasket all injector seals made sure all my clamps are tight. ill do a blt tonight but i dont think thats the problem. wouldnt is surge is there was a boost leak. it seems like a sensor or maybe the isc isnt in the center of operation range so its closed? also my turbo is starting to go out. could this cause my problem. has some in and out shaft play.
 

xaisomboun

Well-known member
Joined
Jun 19, 2011
Messages
117
Location
Minnesota
After you have checked all your leaks and there's still a idle issue, look on top of your throttle body and there is a small screw on top that adjusts idle.

I had the same problem, friend of mine just turned the screw left a little and it fixed the idle. Make sure yours isnt loose though, because as you go over bumps and stuff it goes back to the way it was so secure it in place with some Loctite for threads or something.

Hope this helps!
 

4doorboost

Well-known member
Joined
Aug 19, 2008
Messages
208
Location
Westlake Village, Cali
another thing. when im rolling and i put it in nuetral i do get a little surge from like 1000 to 1500.. thats the only time i get surge and i have to be rolling pretty fast. i have the iac and fiav hooked up also. its like when its warming up it idles fine, but then when i start goin and come to a stop it drops a little low, i get low vac, and my wideband goes a little lean (between high 15 low 16 at idle)
 
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