REALLY wierd idle fluctuation issues... (turbo b18c)
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Joined: Mar 2004
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From: NorCal
REALLY wierd idle fluctuation issues... (turbo b18c)
I did my share of research, nothing quite as odd as my issues...
Car on cold start idles at a steady 1200rpm,( i have the set screw set that high) after driving and still cold it will idle 100% dead on 1200rpm. THEN, after its warmed up, the madness starts and it fluctuates from 800-1200, but only after its fully warmed up. NOW, the wierd thing is, if i apply .4% throttle ( i can see % from my VAFC) it will then hold a perfect 1300 RPM idle with NO fluctuation, but as soon as throttle % hits 0.0% it will flucuate... Which basically tells me it is NOT a vac line leak or vac leak. The TB to mani gasket is good, the intake has never been removed from the head (JDM B16 head & intake)
Car is a turbo b18c on a uberdata basemap and should have zero effect on the idle. Only thing that is setup different from stock is:
--coolant to the TB has been eliminated, but coolant still runs to the IAC
--IAT sensor is mounted on the custom intake tube i made that runs before the turbo, so it sees 100% unheated ambient air temps basically
-- VAFC is ONLY used to read throttle % and RPM's i DO NOT have it rigged for tuning or VTEC changeover programability.
HELP! this fluctuating idle annoys the **** out of me!
Car on cold start idles at a steady 1200rpm,( i have the set screw set that high) after driving and still cold it will idle 100% dead on 1200rpm. THEN, after its warmed up, the madness starts and it fluctuates from 800-1200, but only after its fully warmed up. NOW, the wierd thing is, if i apply .4% throttle ( i can see % from my VAFC) it will then hold a perfect 1300 RPM idle with NO fluctuation, but as soon as throttle % hits 0.0% it will flucuate... Which basically tells me it is NOT a vac line leak or vac leak. The TB to mani gasket is good, the intake has never been removed from the head (JDM B16 head & intake)
Car is a turbo b18c on a uberdata basemap and should have zero effect on the idle. Only thing that is setup different from stock is:
--coolant to the TB has been eliminated, but coolant still runs to the IAC
--IAT sensor is mounted on the custom intake tube i made that runs before the turbo, so it sees 100% unheated ambient air temps basically
-- VAFC is ONLY used to read throttle % and RPM's i DO NOT have it rigged for tuning or VTEC changeover programability.
HELP! this fluctuating idle annoys the **** out of me!
Joined: Apr 2004
Posts: 42
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From: Norman, OK, USA
sounds like the IAC motor to me... Same problem my car has, it only does it once the thermostat has opened and the throttle is at 0%.. You can try pulling the IAC motor off and getting some brake cleaner and then spraying out the carbon that's built up in the mesh. That can fix the problem, or further delay it's complete failure in most cases. Also the IAC will not set a CEL until it completely stops functioning, so it's kind of a rough one to diagnose. I thought I had an Intake leak, so I replaced the IM gasket, and that wasn't it, so i replaced the TB gasket, and that wasn't it.. IAC, ~130 from a discount parts place online, or around 170 from a dealership
-josh
-josh
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Joined: Mar 2004
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From: NorCal
Re: (drives a vtec)
im gonna play around with the POS today. I have an extra AIC, so if all else fails, il swap em out and see.
Do you think because the car is now boosted, it may have affected the AIC? Since it now is seeing positve intake pressue? Not at idle i know, but just thought i'd throw that out there...
Do you think because the car is now boosted, it may have affected the AIC? Since it now is seeing positve intake pressue? Not at idle i know, but just thought i'd throw that out there...
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wedgenix
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May 27, 2005 07:54 PM
