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Atomic EFI stalling and idle problem.

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  • Atomic EFI stalling and idle problem.

    I currently have a small block 350 with a first generation Atomic EFI installed. I ran it for approximately 2500 miles with no problems at all. It now has developed problems I cant seem to diagnose. First thing I noticed was it started dying when you put it in gear on a cold start, then a few weeks later it started having a problem with an erratic idle. Then last but not least, it now sometimes stalls when you stop at a stop sign, but starts right back up. Sometimes at a stop it searches for an idle speed going as low as 400 then up to 1200 before settling down. I've replaced the Idle Air Control and have adjusted throttle plates according to the owners manual. No codes when I checked. Any ideas would be appreciated. I'm about ready to give up and go back to a carburetor.
    Last edited by Daren67; 09-06-2022, 09:47 PM.

  • #2
    I also have the first generation ATOMIC EFI. I have an SBC 383, dual-plane Weiand intake, 4-speed manual. Mine has always been problematic with stalling on stop. I recently added a 0.5" open spacer between the throttle body and the intake. Massive improvement in the stalling on stop. I do have some theories on why this helps, but only guessing at the moment. From everything I've read the stalling on stop is a problem many people face with these throttle body EFI systems, not just the ATOMIC EFI. Would really be nice if MSD or Holley would comment other than telling people to read the instructions. I should also note that I fake out the IAC by setting the target idle speed lower than the truth and then adjust the idle plate screws to get the idle speed I want (this was suggested long ago by another poster in this forum (see Setting the IAC to correct Stalling Issue 09-24-2014, 05:27 PM by hohum).