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Thread: What settings will stop my car from running so rich and making exhaust backfire pops?

  1. #1

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    got my car running and i made a harness to run my handheld into the car to see whats going n

    at idle my AFR are around 12.8-13.4 they jump around a bit

    at WOT they seem to be under 14.

    i messed around briefly with the AFR targets and there is no improvement

    the car runs very good but the smell of unburnt fuel is killing me and my wife when i park it.

    there is a ton of black sut that shoots out my tailpipes when i fire it up.

    I took my pump squirt setting from 28 down to 15 and still no improvement

    i get bad POPS when I pin the throttle hard and let off the ca backfires 1-2 pops faintly.

    I have an MSD Pro Billet and 6AL but im just using Atomic for fuel management, not ignition timing just yet.

    What settings should i adjust to get rid of this rich mixture issue?

    i called MSD they said keep driving it, well i have 70+ miles on it and it hasn't gotten any better.

    thanks guys


  2. #2

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    Are you sure the O2 sensor does not have a leak? The only way I see that those readings should give soot is if it is seeing false readings from the O2.

  3. #3

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    No i checked the O2 is mounted snug and the bong has a really good weld all the way around, no O2 errors just on start up but they go away which MSD said its normal.

    Any other suggestions I can check into? Would the location of my temp sensor have anything to do with this?

    the car runs strong as hell, best it has ever run in years. I just want to remove some fuel from the calibration and stop smelling like a gas can, this was one of my main reasons for going EFI the carbs can be tricky to tune on a regular basis against this condition

    car has a comp cam duration at 0.50 is around 233

    i set my camshaft selection in the middle

    Would my ignition timing have anything to do with this?


  4. #4

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    fcsallan wrote:
    Are you sure the O2 sensor does not have a leak? The only way I see that those readings should give soot is if it is seeing false readings from the O2.

    gotta question regarding what you mention the kit came with a copper washer which looked like the ones you see on an oil pan drain plug. I assumed it was for the O2 sensor but the O2 sensor seemed to have a thin washer or two thin washers i cant recall and this copper washer didn't fit over the O2 threads so i assumed it wasn't for the O2

    could this be my issue?


  5. #5

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    Regarding the cu. washer, according to MSD Tech, it is to be used with

    the temporary O2 bung plug if you need to operate the vehicle before

    installing the Atomic system. It is not used with O2 sensor!

  6. #6

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    you may want to check the intial settings, cam and cubic inches and make sure they are correct or try the different cam setting to see if it makes a difference. I do believe they set the fuel curve for the engine.

  7. #7

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    I tried the cam to large and no difference, on the Atomic Dash the AFR at idle is anywhere from 11-12.3 which is really rich, when cruising it stays well below 13 and at WOT its around 13.5. I reset all my targets and all and checked the O2 sensor. I need to call MSD tech Monday, maybe its a bad O2 sensor or something? I plan to remove the O2 later today when the car cools down to see if the sensor is covered in black from the richness of the burn.

  8. #8

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    I played around with the AFR targets and had my friend come for a good 40 min drive tonight. the AFR are much better than prior data loging but they jump around alot. They seem to be between 13-14.3 at cruise, idle and WOT. They are no longer going in the 10-11 range or the low 12 range.

    If I am at WOT for a good minute or so then let off the AFR shows 50 to 20 then it balances back out.

    I think for now its much better and I plan to retard my ignition just a tad to see if that stops the off throttle pops after hard acceleration

    one thing that worries me is after driving the car hard and coming to a dead stop the cars idle drops and the car sounds like it wants to stumble and die. Any idea what is causing this? it only happens when I brake hard and come to a complete stop after i was hauling ass. Can the vacuum from the power booster be causing this symptom? Fuel sloshing around and fuel pumps targets getting thrown off? i would like to correct this.

  9. #9

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    What is your IAC (in gear if automatic). The dying when you come off throttle is typically a blade adjustment issue.

  10. #10

    Default What settings will stop my car from running so rich and making exhaust backfire pops?

    My car is a 4 speed. I checked everything now with my gauges and my vacuum is great at idle it's 16 and on acceleration up top 28. once i hit my power brakes the needle on the vacuum gauge drops to 10 then 12 then back up to 16. Can this be a throttle blade adjustment for sure? Upon installation i just adjusted the front throttle blades to get my idle to come down. I set my idle target at 850 and once the car warmed up the idle was around 1100 so i adjusted the idle blade on the front to bring it down to my level. I never adjusted the rear throttle blades. What exactly is the IAC setting and how would this pertain to what i am experiencing?

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