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Thread: New cold idle issue

  1. #1
    Tuner in Training
    Join Date
    Aug 2008
    Posts
    18

    New cold idle issue

    I'm looking for some pointers to troubleshooting an odd condition, happens in open loop where if I try to drive it, ie back out of driveway, it will stumble and struggle to find idle. If I drive it for a bit, as soon as I hit a stop it will struggle with idle. Restarts are rough and require some throttle playing. I've got nothing in sensor readings really for this time since I have to wait for the car to cool down significantly to reproduce and even then, its not 100% guaranteed it will re-occur. Once I hit closed loop, all is well. So I've got the option of wait 2 min for car to warm up to closed loop from cold start or try to fix tune.

    I've been toying with the idea in my head that my "cold air" intake has messed up my idle in the VE but I've tried to ensure datalogging once the IAT are normal and I'm on the road for it not allowing heat soak during logs.

    I uploaded the cfg I was using to monitor everything along with 2 logs of after I dialed in my street tune portion for both the SD and MAF. I spent a good few hours of tweaking the SD portion over various days and finally getting the MAF to match.

    I was also going thru the tune and found some oddities that the tuner had done to my car, in Engine, Fuel Control, OL & CL and found anomalies vs a stock 98 tune in which the areas relating to open loop may be the issue. The open loop EQ ratio is lessened for all areas 122 F and less and 55 and less. This would be the area that stumbles in open loop for me but am not sure if I should bring back to stock, increase or further decrease.

    running
    L92 6.2L
    5.3 heads stage 2.5 65cc
    LS6 intake
    0.615/0.608 lift 230/230 115+2
    60lb injectors
    m6 emissions equipment intact

    Also had a thought on fuel pump but have racetronix hotwire kit on stock pump and ran a mechanical guage and pressure was ~58PSI or so

    I can only log 24bit 98 pcm so I deleted the O2 mv reading

    Any thoughts or suggestions much appreciated!
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    Last edited by Slade; 04-16-2012 at 12:58 AM.

  2. #2
    Tuner in Training
    Join Date
    Aug 2008
    Posts
    18
    So I did some IAC logging using the Raf cfg file.

    I found my IAC counts to be 114 on average and for some inexplicable reason after reflashing I have a new "stumble" from a cold start. Restarts are better but that initial after starting bugs me.
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