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Slight misfire thru rpm range

Discussion in 'FAST Support Forum' started by fishhore, Apr 17, 2018.

  1. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Check the MAP.
     
  2. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    I have done the tps wizard a couple times after setting my iac this week. As far as visually the throttle blades look closed in the rear. Car had been running great after getting timing all squared away for now. Forgot to mention I picked up a new tab from moroso that is just the needle pointer that is adjustable since I have a balancer with degrees etched into it and got tdc with a piston stop and found out I was at almost 40 all in so lowered it back to 34 all in as per the engine builder. Initial is at 14 with that. Will dial it in further when I get a new dizzy soon. Also map sensor has been replaced last year to the style u run.
     
  3. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    It runs hard now and seems much happier but still cuts out at light throttle. Tps % from 1 to about 3 it just does not like. If I get on the throttle it does great, but when the tps% is low is when it cuts in and out.
     
  4. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    This is mostly timing related. The initial needs to be raised and the vacuum set properly. The new distributor will change things considerably. Please remove your off topic comment in the COMP cam forum.
     
  5. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    I agree my initial could be higher, my total is where it’s supposed to be. I should be able to run without vacuum advance. I would rather run it but it just makes problems worse. I understand my timing isn’t dialed in perfectly for the vacuum advance or initial but my engine should run ok with the timing how it is set now. It should not be cutting out while cruising with the timing how it is.
     
  6. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    I replied to a post from someone who is having similar issues to me?
     
  7. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    Now if I get the ready to run 8360 can I get rid of my 6a box. I’d rather have less wiring and one less thing to fail.
     
  8. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    That thread is off topic and shouldn't be in the COMP cam forum. That forum is for cam advice.

    Thanks
     
    Last edited: May 12, 2018
  9. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You want to run the MSD box with the distributor. The multi-strike provides many benefits.

    Once you get the initial dialed in higher, the advantage of vacuum timing will help stabilize/steady part throttle rpms preventing the hunting at a steady pedal. The load % of the canister will also allow higher total timing in low load situations which will improve fuel mileage - considerably in many cases. You'll be able to adjust the canister load % and total vacuum advance with the new distributor. After working on the timing, you'll be able to fine tune the A/F even better. Overall gains will be more low rpm toque and better fuel mileage - including a performance boost throughout the entire rpm range due to improved A/F ratios.
     
  10. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Get the new distributor installed and I'll help you set it up.
     
  11. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    Pro billet and coil on the way. Just went with the blaster ss coil. Didn’t want to shell out another 80 bucks for the blue one
     
  12. A A

    A A Well-Known Member

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    Jun 22, 2014
    The standard canister oil-filled Blaster will work fine. It just needs to be mounted vertically.
     
  13. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    The ss blaster is like the blue one u suggested. Can be mounted however
     
  14. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Yes, missed the ss. It's also compatible with your MSD box.
     
  15. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    Dizzy should be on my porch when I get home from work tonight. So black bushing u were saying and correct springs already r in it. 34 total with 16-20 of that being at idle.
    Now about vacuum advance, I don’t have ported so I will be running full vacuum so should I actually run my initial lower so that with the vac advanced hooked up my idle timing is around 16-20?
     
  16. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Black bushing, and it should come with the two heavy silver springs installed.

    What TBI are you running? Look for a vacuum port just above the throttle blades.
     
  17. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    I have ez 1.0 the ported nipple makes vacuum at idle
     
  18. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Yes, it allows some vacuum at idle but increases the vacuum signal stronger there as the throttle increasingly comes off idle and is held steady. Use that port with the distributor. You'll be able to adjust how the canister uses ported vacuum. If the vacuum signal is too strong, you can add a filter bleed-off and one way valve in the line, or a restrictor valve.
     
    Last edited: May 15, 2018
  19. fishhore

    fishhore Member

    Joined:
    Aug 15, 2014
    Ok installing black bushing in the dizzy now. 16* initial should put me at 34* total with that bushing. I have double checked that heavy silver springs are already installed.
     
  20. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Since you are now using the heavy silver springs for a higher slope, you will be able to safely increase the total mechanical timing by simply raising the initial. Find the initial, the engine likes, by using a vacuum gauge to find the highest steady vacuum at idle while raising the initial - then back off two degrees. If the mechanical total is still under 38, try using the new higher initial setting. Do all of this without the vacuum connected for now. This may not correct the part throttle rpm hunting until the next step can be taken. For now, just make sure there is no detonation or plug fouling indicating any pre-ignition. You may need to adjust F/A first, or lower the initial by two more degrees.

    You want to find the optimum mechanical timing first. Then, (step two) you will work with adjusting the vacuum timing. With the vacuum adjusted properly, your total timing should easily reach 44 degrees.
    .
     

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