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Thread: 302 Backfire through Throttle Body

  1. #1

    Default 302 Backfire through Throttle Body

    So it's been two weeks since I have installed the Atomic EFI. I set everything up using the most recent updated instructions found on the atomic site (I have old instructions form Apr of 2012 that are very different, specifically with setting up the timing control.)



    I have the atomic EFI controlling timing etc. I had a problem with the car dieing when shifting gears. Per the tech line, I increase my idle RPMs (set target idle to 1,025, but idling around 950) and solved that problem. Now I have a problem with backfiring through the throttle body that I never had before. It happens under two different circumstances. 1. when trying to get the car from a stand still into 1st gear. and #2 when I am cruising (doesn't matter what gear). it happens between 1,600 and 2,000 rpm and usually when there is slight load (like going up an incline). It almost seems as if the car doesn't like to cruise/ or be in gear below 2,000 rpm without backfiring. How do I fix this?

  2. #2

    Default 302 Backfire through Throttle Body

    Try an initial timing setting of 15 degrees @ 1000rpm and check to see if your phasable rotor cap has shifted and/or loosened. Mine came loose during initial install and caused the backfiring you mention. Tighten the set scew on the rotor cap with blue Loctite.

  3. #3

    Default 302 Backfire through Throttle Body

    Is the fuel system set up with a return?

    If so, where is the regulator (before or after the throttle body)?

  4. #4

    Default 302 Backfire through Throttle Body

    I will try advancing the timing and will check out the phaser rotor to make sure it didn't move. I do recall that I am running at 10 degrees btc at idle.



    *MSD Support: The fuel system is setup without a return. I used the kit that came with the EFI.

  5. #5

    Default 302 Backfire through Throttle Body

    Were you able to check the rotor phasing.

  6. #6

    Default 302 Backfire through Throttle Body

    I will say that it is absolutely amazing how the EFI system works when the timing is adjusted. I was running with the systems 10 BTC and the car ran like crap! I had raised the idle RPM up to 1025 to keep the car from dying when letting off the clutch or coming to a stop. I advanced the timing as suggested above to 15 btc and noticed that a lot of the problems I was having before were gone. I will say that I found out that 15 btc was too much as I started backfiring through the tailpipe when accelerating hard and letting off the gas quickly. 13 btc seams to be the sweet spot. the car likes to cruise under 2k, doesn't back fire in any way, and doesn't sound like it want's to die when coming to a stop...........



    HOWEVER AND A NOTE TO ALL THAT HAVE THE PHASER ROTOR- After driving my car with a smile on my face, I found my self stuck on the side of the road. To make a long story short, the phaser rotor screw came loose. Get some locktight and put it on the phaser screw before you are left on the side of the road like i was!



  7. #7

    Default 302 Backfire through Throttle Body



    Stangatic wrote:

    I will say that it is absolutely amazing how the EFI system works when the timing is adjusted. I was running with the systems 10 BTC and the car ran like crap! I had raised the idle RPM up to 1025 to keep the car from dying when letting off the clutch or coming to a stop. I advanced the timing as suggested above to 15 btc and noticed that a lot of the problems I was having before were gone. I will say that I found out that 15 btc was too much as I started backfiring through the tailpipe when accelerating hard and letting off the gas quickly. 13 btc seams to be the sweet spot. the car likes to cruise under 2k, doesn't back fire in any way, and doesn't sound like it want's to die when coming to a stop...........



    HOWEVER AND A NOTE TO ALL THAT HAVE THE PHASER ROTOR- After driving my car with a smile on my face, I found my self stuck on the side of the road. To make a long story short, the phaser rotor screw came loose. Get some locktight and put it on the phaser screw before you are left on the side of the road like i was!




    We had one of the cars on our Tahoe trip have the same problem, the screw holding the rotor in place loosened up and came out. The other two cars with the phase rotors were checked and found to be tight. Both those cars had a couple of thousand miles on the install. We Loctited them anyway. That being said, the washer in the kit that is used with that screw is a Belleville washer. There is a right and wrong way to install it. Install it wrong and the screw will back out. It's easy to miss in the instructions, especially for people like me! I missed it in the instructions, but I work with those washers, so I recognized what it was and made sure to install it correctly.



    Gerry

  8. #8

    Default 302 Backfire through Throttle Body

    Thank you Gerry for the assist.

    The Belleville Washers do need to be installed with the dome up (concave down). If these are installed upside down they will not work properly.

    It is a good idea to apply some threadlocker to help keep the screws in place.

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