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

  1. #11

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

    I have a 4 speed @ 850rpm and it is set at 10 to 15 when the motor is at temp.

  2. #12

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

    IAC can certainly do it. If you open one blade more than the other or have them moving independent of each other you will get odd results at different throttle positions.

    Always adjust the front and back together and always in very small increments in order to get to the target IAC readings. This makes a world of difference in idle and driveablity.


    [hr]
    The instructions say:

    THROTTLE BLADE ADJUSTMENTS

    Note that there are three adjustment screws on the

    linkage (Figure 5). One adjusts the opening of the

    front throttle blades to assist with idle and tip-in.

    The rear blades also have a similar adjustment.

    These may require adjustment, depending on your

    engine. It is important that the front and rear open

    at the same time. Page 14 has more information

    on adjusting the throttle blades on initial start-up.

    There is one more adjustment that controls the

    front and rear throttle blades opening at the same

    time. This is set at the factory, but each application

    may require slight adjustments to receive the best

    driveability.

    And:

    THROTTLE BLADE ADJUSTMENT

    There is one more adjustment to review prior to starting

    the engine for the first time; the Throttle Blades. This is a

    setting that varies between engines due to improve idle

    characteristics due to engine and cam size.

    There are two adjustments that determine the position of the

    throttle blades, a front and rear (see Figure 3). Note that the

    front and rear throttles need to be at the same setting and

    open at the same time. They also need to be opened the

    same amount to produce the best idle.

    For initial start up, MSD recommends the following:

    • On an street/stock type cam, turn the throttle screws ˝ turn from the point where the blades first

    start to move.

    • For a mild cam, turn the screws one additional turn from the point where the blades first move.

    • For Larger cams, turn the screw 1˝ turns from the point where the blades first move.

    Once started, you will be able to monitor the IAC count (Idle Air Control) on the Handheld in the dash

    mode to improve or tune the idle. When the engine is at operating temperature, let the engine come to

    an idle and monitor the IAC count. This count will range from 0 – 200 and at idle, a rule of thumb would

    be 10 - 20 with a manual transmission and 5-15 in gear with an automatic (less is ok).

    If the count is too high, the IAC is trying to open too much and the blades should be opened to help

    with additional air flow at idle. Make any adjustments equally in front and rear using small steps such

    as a quarter turn at a time.

  3. #13

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

    Ok i just got the car warmed up and was checking the IAC it started out at 5 then dropped to 0 when the car got up to operating temp. As i hit the throttle the IAC jump up to 30-40-50+ I adjusted both throttle plates and i can not get the IAC off of 0 unless i open the throttle enough that my idle is at 1800 RPM or more. When my idle is racing i can get the IAC around 10 or 15 and when i goose the throttle it doesnt stumble at all but the idle is just way too high. What can i be doing wrong or possibly wrong here?

  4. #14

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

    note i only adjusted the two allen head screws on the linkage side of the throttle body, i am know reading there is a 3rd screw adjusted at the factory. I can not find my instruction sheet in my garage. can this 3rd screw be the one i really need to be messing with?

  5. #15

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

    I just had a friend over and we adjusted the blades perfectly. The cars idle still drops for 2 seconds when coming to a stop. My IAC is reading 0 at idle and no matter what it doesn't go up. Only at part or full throttle does IAC move up from zero. We unplugged the battery but this did not erase initial settings.

    So two issues why is my IAC stuck at zero, no error codes. I am now certain this is the cause of idle issue. Secondly what is the proper procedure to erase all Atomic settings to start over? I think this is why my IAC is stuck at 0 .

  6. #16

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

    I'm not sure a reset will fix that. The IAC is a reading as I understand it is the amount that the Atomic needs to open the blades to maintain the settings that are in your programming. Zero should mean that the Atomic does not need to adjust the blades to reach the readings that it needs. I could be wrong, that is as I said just how I read the settings. Either way, my IAC could not be brought above zero either until I pulled the ping and washer off of the adjusting rod and readjusted the blades to open at the same time. My front was opening more than a 1/16' before the back would start to move. I made them move together and I was able to get the idle under control and brought the IAC up a bit. It is still at or near zero now at idle and about 5-10 in gear but it idles very well.

    [hr]
    So if you look down into the TB now, do both blades open at near exactly the same time?

  7. #17

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

    fcsallen so having an IAC of Zero at idle isnt necessarily a bad thing you mean? I was just confused as why the car went from all over the place to all of a sudden to zero at idle. once the idle goes above 2000 the IAC jumps up. I think my idle stumble has something to do with this IAC reading and i spent over an hour adjusting things with no change from Zero IAC

    would you happen to know how i can do a hard reset on my system?

  8. #18

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

    What is your fuel pressure set at? return system or returnless? I had similiar problems and discovered my return type system wanted about 50 psi, not the 60 i was running at.

  9. #19

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

    motorhead446 wrote:
    What is your fuel pressure set at? return system or returnless? I had similiar problems and discovered my return type system wanted about 50 psi, not the 60 i was running at.

    my set up is returnless and my PSI at idle is anywhere from 30-38 and much higher when i have a load on it and full throttle

  10. #20

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

    Spoke to an MSD tech about 30 min ago and he wanted me to remove the IAC from the throttle body and turn the key on to check it if it moves.I ran home for lunch and just did that, the IAC moved in just a hair then the pin shot out of the housing and hit my hood. I do not think an IAC supposed to do that but the threaded pin looks to have worn the inside part and was loose. Waiting to get another MSD tech on the line to verify this is not normal and have them send me out a new one. At least something makes sense why my IAC was stuck at Zero.

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