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Thread: Idle hunting during quick revs at idle

  1. #1
    Tuner in Training
    Join Date
    Apr 2016
    Posts
    34

    Idle hunting during quick revs at idle

    Hey all, little help here....

    Have an 03 Z06

    AFR 210's
    FAST 90
    SVO injectors, i believe the early TBird 36lbers
    Full header/exhaust system
    Granatelli MAF w/BBK CAI
    Unknown cam
    RPM Lvl 5 Transmission and Rear (3.73 gearing)

    Picked up the car for a great price. Previous owner couldn't tell me exactly what was done to it. Easy to tell that it previously was a nitrous build due to the holes in the trunk cubby, and the WOT switch behind the gas pedal. No idea on the cam either.

    Anyways, grabbed it for cheap. Very clean car and could tell the car had some money dumped into it. Lots of carbon fiber bits and pieces on the interior, as well as wide body rear fenders which weren't mentioned in the for sale ad.

    I think the injector data may be screwy, as i can not see idle pulsewidths below 2.1. I say that, as previous tunes ive worked on have always shown me low 1's at idle. As well as that, i had to lean the tune out greatly, as it was set for nearly 10.9 AFR at WOT, im assuming for the nitrous. The Granatelli MAF i have read, is not that amazing, and can cause issues, but i have ran a few logs and tuned that to the best of my ability as well as worked on the VE tune to +/- 2 or 3 in most cells.

    The thing that is really stumping me is the idle section of the tune. I have ran Russk's config multiple times, and I always get numbers much lower than what I am currently running. Using those numbers, i cant get the car to idle. I end up having to add to the BRAF numbers till i can get a running car. Even then, if they arent upped quite enough, I end up killing the car pulling out of my driveway before its warmed up. The numbers i have currently, will start the car up without any flaring, then will allow the car to immediately pull out of the driveway and be along its merry way. After looking at multiple other tunes, it seems as if my numbers are sky high.

    Along with that confusion, I am having an issue with low idle situations. Coming from a stop and either reving in neutral, driving slowly through a parking lot, or in traffic and bumping the car up a few feet in 1st gear. The car has a big problem with finding its idle after a temporary rpm increase. It will rarely die, but on occasion it will. Especially at a low roll through a parking lot.


    I have matched up high octane/low octane spark tables with idle spark tables... I have played with follower/cracker after reading a few suggestions... No luck as to getting this thing to behave.

    The car chugs a bit at takeoff, or at low speeds in a higher gear. But i can live with that, somehow my previous turbo c6 was a bit easier to work with and i was able to have that sail at 40mph in 6th gear... No such luck yet with this c5...

    Attached tune. No log as of right now of the idle/revving issues. Can get though.


    Lemme know if something sticks way out in the tune

    Idle changes and injector stuff.hpt

  2. #2
    Tuner in Training
    Join Date
    Apr 2016
    Posts
    34
    20-05-29 09-12-57.hpl

    Here is a quick log from this morning. Took the car out for a little drive. Car comes to idle just fine after a romp on it, then slowing down to speeds and coming to a stop sign.

    The very end of it, i sit in my driveway and twice rev it in neutral. Car dips, but catches. Last rev I had it in first (dont think it really matters if it were in gear or not, i just got lucky the first two revs), and it dips and dies.



    I am also seeing the sporadic KR, but seeing as how it was recreated at then end with those throttle stabs in the driveway, im gonna lean towards the motor mounts needing replacement, or even the high flow cats on the x-pipe.

    Moreso worried about the hunting and dying at low speed throttle stabs. Those affect the driveability here in Houston traffic.

  3. #3
    Tuner in Training
    Join Date
    Apr 2016
    Posts
    34
    Anything look wonky to anyone? Are my BRAF numbers sky high?

  4. #4
    Tuner in Training
    Join Date
    Apr 2016
    Posts
    34
    bump

  5. #5
    Potential Tuner
    Join Date
    Mar 2020
    Posts
    1
    im dealing with the same problem after installing a new higher stall converter i bumped the rpm up by 100 and it decreased the issue of actually stalling. but its still not right