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Thread: Would not restart

  1. #1

    Default Would not restart

    Finally completed my install and the engine fired right up! I was so happy it worked the first time.

    Fairly rough idle though, even after warm up to 185.

    Its a 69 Mustang, 428 Cobra Jet, Comp 275DEH cam, C6 auto, factory distributor with Pertronix 1, Pertronix Flamethrower coil, Atomic timing control disabled, MSD 6AL-2 ignition, Fuel pump within 10" of tank PWM mode returnless, used MSD supplied fuel line. Atomic cam selection mild/medium, idle RPM 750.

    I had not yet updated the firmware so it still had what the factory installed: Dash 1.0.29, ECU 1.0.116, Power Mod 1.0.5

    After a warm up to 185 I adjusted the throttle blades equally for IAC of 0 - 5 with the trans in gear and then the idle went up to 900 and would not come back down to the target I set. Prior to the adjustment the idle varied around 750/800. Shut engine off, restarted OK.

    Decided to go for a test drive. 5 miles and it was running great at higher speeds though seemed like it was going to die when I stopped. Idle still rough and surging. Went another 10 miles and running great at speed, when I stopped the idle was very rough and surging heavily. IAC was up to 30+.

    Shut off engine for 5 minutes. Then would not restart, just cranked over with an occasional sputter. Tried the flood procedure, just cranked with no sputter. Handheld showed fuel pressure around 40 and cranking RPM. Moved the throttle blades back to initial setting, no fix. Reset the Atomic, no fix. Eventually the battery ran down.

    Ran home for battery cables, also picked up the carb, fuel pump, fuel lines, and other parts removed to install the Atomic.

    Jumped the battery and tried many times to restart, just cranked over with a rare sputter.

    Two hours later I had the carb and the rest of the old parts reinstalled, and all the Atomic equipment disconnected/removed. Engine started on the first crank and I was able to drive home!

    I'm fairly busy next week so may not be able to call MSD until the following week, but does anyone here have any idea what may have happened? Or what I should look into to correct this?


  2. #2

    Default Would not restart

    Unfortunately there isn't enough information to determine what happened.

    We can start with some basics.

    Verify the two main power leads for the Power Module are connected directly to the battery (heavy Red to pos, thin black to neg).

  3. #3

    Default Would not restart

    Red was on the battery, black was on engine ground.

    Also, air temp was about 70.

    It will be at least a week before I will have time to hook it all back up and try again.

    And I must say, I am hesitant to hook it back up.

    This is the first time I have been dead on the road for many many years.

  4. #4

    Default Would not restart

    Called MSD support on 7/18/13 and spoke with Joe. He was completely unwilling to read this post to get him up to speed on this problem, I was surprised at that. Anyway, after attempting to diagnose why I may not be getting spark (and me telling him it runs fine with the Holley carb in place) he says he has no idea why it wont start and to put the Atomic back on. OK, fair enough.

    First I installed the current firmware: Dash 2.0.3, EFI 1.1.1, PM 1.0.7. I have the Atomic system reinstalled and it cold started after a lot of cranking. Idle was fairly smooth with IAC at 0 - 8 after warmup to 185 with C6 in gear. Idle was set at 750 in the handheld, car is idling around 800 -850. Shut off and restarted several times OK.

    Also, I did move the black wire from engine ground to battery negative.

    Took it for a short 2 mile or so drive then back to the driveway to try a restart. Restarted OK but idle was rough and IAC up in the high teens. Adjusted the throttle blades so IAC was back in the 0 -8 range, idle went up to 950 -1050 erratically and surging. Went for another test drive, less than a mile it was running rough and stalled at the first stop sign. It did not want to restart, but if I madly pump the throttle it started. Drove it home all the while pumping the pedal to keep it running.

    Sitting in the driveway(thankfully) the IAC was up to 175! and I also noticed learning mode was OFF.

    The only way it would run was to constantly pump the gas pedal.

    Seems like the farther I drove the worse it got, same thing that happened weeks ago on my first attempt when it stranded me 15 miles from home.

    My final readings after limping home were very erratic as the idle was all over the place with frequent help from me to keep it running:

    ECT 205

    IAT 124

    TPS 0

    MAP 16 - 25

    Fuel Pressure 38 - 42

    Batt 13.9

    A/F Ratio 12 - 26

    Inj Duty 7 - 11

    IAC 175

    Learning mode OFF

    High ECT and IAT were probably due to sitting still idling.

    I will call MSD again on Monday but I am open to any ideas from the forum, especially MSD techs!

  5. #5

    Default Would not restart

    Did you notice a loud vacuum sound coming from the throttle body while the IAC read 175?

    If not, this could indicate that the IAC is stuck closed or became disconnected. The IAC motor is on the back side of the throttle body, please check the connector to make sure it is fully connected to the IAC motor.

    If there was a loud vacuum sound, the throttle blades may be closed too much and the IAC is trying to compensate.

    The throttle blades must be adjusted with the engine at operating temp and the transmission in gear (drive). If they were adjusted only in neutral or park, the engine may have a difficult time idling in gear.

    Learning will be OFF at Idle, WOT, and anytime the engine is below 160°F.

  6. #6

    Default Would not restart

    Yes, there was the occasional loud vacuum sound coming from the throttle body. But it was running very poorly before the first time I heard it.

    I did the throttle blade adjustment as per the manual, at temp and in gear. Idle got worse the more I opened the blades. Also, the idle just kept going up and up as I opened the blades. The handheld setting of 750 RPM didn't seem to matter.

    I need to hook up my electric fan to assist the engine fan and then I will be giving MSD a call.

    Should the IAC reading stay steady after I am done adjusting the throttle blades? The IAC slowly climbs up all on its own after I am done adjusting.

  7. #7

    Default Would not restart

    The IAC count should be able to go down as you adjust the throttle blades more open.

    As you throttle it the IAC will follow the with the throttle position; this helps it to save the engine from stalling on sudden decel.

  8. #8

    Default Would not restart

    Thanks for the info, that is what I expected should happen.

    What I was seeing is "IAC creep". I had is set at 8/9 and then as you continue idling it would creep up. Got to 38 on its own without me touching anything before it stalled out.

    And then I was back to my original problem, it would not restart!

    Called MSD support and got Ray, he is a super tech and very helpful.

    After much diagnosis I have an RMA to return the throttle body for repair or replacement.

    Next update will be when I get the throttle body back and have the car running again.

  9. #9

    Default Would not restart

    I have the exact same problem and basically same combo. Certainly need a resolve for this most irritating issue.

  10. #10

    Default Would not restart

    Talked to the MSD RMA person yesterday. She says it may be up to two weeks before they send my throttle body back.

    Since I haven't been able to enjoy driving my car much the last couple months I put the Holley carb, old fuel pump and lines back on and just went for a nice drive down the Oregon coast. Engine runs great with a carb!

    UNVme2, what is your setup?

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