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Odd idle and hunt Subaru GC8 1999


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Hey guys can't seem to figure out a weird idle hunt after stabbing the throttle, or even when just pulling up to the lights. doesn't do it every time, worst with the A/C on.

Carried out smoke leak tests for vac leaks, Cleaned ISCV stepper motor, not using MAF sensor. 


Hunting idle with AC on after stabbing throttle Lambda AVG Drops to zero.llgx hesitation issue after stabbing the throttle.llgx

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Really need to see the tune also, but a couple of things that jump out.  

  1. Your overrun fuel cut is hyper active and cuts in almost instantly as soon as you lift off.  In the log with AC on the overrun fuel cut is bouncing on and off as you approach idle.  Either turn it off as a test or give it longer activation delay and possibly increase the deactivation RPM.
  2. You have an occasional trigger error, maybe something simple like arming threshold.  Do a triggerscope around normal idle RPM and I will take a look.
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Just got a log this morning on the GC8, after adjusting the over run fuel settings. Took it for a solid drive this morning felt pretty good. Till i got back and parked it up, left it idling for awhile, with a/c on to see if it would fault didn't. Until i put it in reverse then it went nuts and just kept bouncing idle from 2000rpm to 1900rpm. made no difference turning on or off overrun fuel cut. switching the car off and back on again, it returned to normal straight away and doing the same thing it wouldn't fault. hopefully something in the log will stick out, i couldn't see anything personally.

Had to compress the file due to being slightly too big.

hunting like crazy while idling after reversing and stopping.zip

TriggerScopeLog 2.llgx

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The RPM is rising above the RPM lockout so idle control is not attempting to bring it back down.  I think this is possibly the AC offset table numbers too big.  Typically they dont need as much as you have.  Try zeroing out that table.  

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