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Thread: odd off idle issue

  1. #1
    Senior Member
    Join Date
    Apr 2007
    Posts
    114

    Default odd off idle issue

    I have a 96 k1500 with a 411 PCM.

    I'm running SD right now and have done the Auto VE tuning.

    If I hit the gas to bring it off idle when in park or to pull out, it goes way lean and stutters, then picks right back up.

    This only happens within the first 5-10 minutes of start up.


    On the other side of things, when i go back to MAF this issue goes away but my long term fuel trims go beyond 25%

    Should I just tune the maf and run that way. Is there an upside to MAF over SD or the other way around


    thanks

  2. #2
    Junior Member
    Join Date
    Aug 2006
    Posts
    33

    Default Check for codes ?

    This is interesting ... not sure if this will help.

    We are running the 411 on a 1933 Willys (modded '87 IROC engine).
    It is also a SD system. We started with an express van tune and completed the "MAFless" section of the custom operating system. Everything was fine at this point. I had the VE dialed in (+/- 3%), then the MIL started coming on (but it was flickering). It was throwing a code ( I think P0650 or P0605). I also noticed when the code was thrown ... bank 2 would go way lean (25%). Bank 1 was fine. Really odd.

    We found that the wire for the MIL light had been pinched and was actually getting a very weak ground (wire insulation was cut causing the flickering). Exactly what the code was telling us.

    Anyway, once we fixed the wire. The problem with Bank 2 going lean was gone.

    It doesn't sound like this is your issue, but I'd start by checking for DTC's. BTW, I was told when using SD (MAFless), not to disable the MAF Trouble code (We do have one, I forget the actual code) ... but to leave it there and just set it to No MIL. Not sure why, but it works.

  3. #3
    Senior Member
    Join Date
    Apr 2007
    Posts
    114

    Default all good on the wiring front

    thanks.

    I dont have a trouble codes aside from the MAF codes. I believe I got it taken car of though. I had lowered my fuel pressure and did change the injector flow rate in the tune. The value that was prgrammed was 24.074#/hr and the actual was 23.3875#/hr. It suprises me that that small of a discrepency would cause it to go as lean as it was. But it does explain why it only lasted a second and then the fuel trims picked up.


    Anyone have an opinion on MAF or MAFless. Is one better or worse for everyday driving?

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