Help with tune, goes randomly extremely lean

Discussion in 'SD and SD2 Chip Support for Buicks' started by Travis Byrd, Sep 21, 2019.

  1. Travis Byrd

    Travis Byrd New Member

    Need a little help, i have been trying to get this tune down and thought i had it rich but headed in a good direction at WOT. But then i will do pulls on the same day with essentially the same tune and get a huge lean condition as shown in the log. The correction also does not seem to start working until its way to late. Im not sure if its a failing alky pump, blowing out spark, fuel pump issue, or maybe voltage issue. Any help would be appreciated, thanks

    SD2 powerlogger running speed density w/ alky.

    Attached Files:

  2. EricM

    EricM Administrator Staff Member

    It looks like possibly an alky problem, or fuel system, but the fuel pressure appears ok.

    The correction is working, and pushed the injector duty cycle all the way to 100% to try to compensate, but it can't do any more than that.

    Here are the 2 runs compared. You can see approximately the same rpm and boost, but the duty cycle is much higher on the lean run. Also, I'm not sure why your RPM's flared up like that on the bad run.

  3. Travis Byrd

    Travis Byrd New Member

    Thank you for looking at that, i found it tonight it was a broken vac line going into the FPR. Car is really rich now since i tuned it with that leaking, but at least i believe i found that problem. Thank you again.

Share This Page