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Thread: Random hot idle issues

  1. #1
    Join Date
    Aug 2018

    Default Random hot idle issues

    Having some trouble with stalling when hot at idle when restarting after 10 min or so. Car starts first go, and idles happily for about 5-10 seconds until it the IAC count starts to drop, the engine then runs rough and the IAC count starts to go up (as the MSD tries to stop the RPM drop) but it’s not quick enough to catch the stall. If you catch the stall with the throttle it will idle happily at 900-1000RPM with an IAC count of 0. Cold start is good, no issues. General driveability is very good. I would like the car to idle a bit lower if possible as well, can adjust the throttle plates but it struggles to keep running when holding in D at idle. IAC count in D is quite high as the manual recommends 10-15 but to achieve an IAC count of 10-15 in D my base idle speed needs to be somewhere around 1200-1300rpm set on the butterflys.

    351 Cleveland, stock cam
    Distributor controlled timing, 10° idle / 32° full advance vacuum off, vacuum advance on 22° idle / 42° full advance
    Running return fuel system with regulator, PWM pump. (configured as such in handheld unit – PWM with return)

    The box is running 1.2.12, is it worth updating to 1.2.14? Is that update aimed at an issue similar to this?

  2. #2
    Join Date
    May 2018


    I had similar issues with my initial installation settings on my Mustang 302. I redid the idle settings and idle speed which had minimal improvement on the issue. I'm using the timing control and eventually what made the biggest improvement was increasing my base timing from 10 degrees to 18. I also added an open spacer under the base as I'm running a dual plane manifold. I did upgrade the firmware to the latest too, but can't say for sure there is any difference from that.


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