Signs Of A Msd Ignition

Discussion in 'Classic Mustang Specific Tech' started by Sixty7Restomod, Dec 16, 2008.


  1. Sixty7Restomod

    Sixty7Restomod New Member

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    Whats the signs of a bad msd ignition. My car will crank but won't fire. I'm trying to narrow the problem down. I have a 6al and did a spark test which it passed. Does that mean I can completely eliminate the chances of that being the problem?
  2. dodgestang

    dodgestang Active Member

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    I would replace the cap and rotor.
    My MSD setup has left me stranded on the side of the road twice in 2.5 years and both times I had to put a new cap and rotor in to get it going again (the first time obviously I put a new pickup in, replaced the coil, checked the box, rewired the ignition, all to find out the cap went bad.

    Both times...just driving down the road the car simply shut off.

    Now I have an extra cap and rotor in the glove box at all times...which obviously means it will never happen to me again.

    And yes, if you short the control wire and it fires a spark the box is fine.
  3. HookandLadder

    HookandLadder Founding Member

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  4. 2nd Mustang

    2nd Mustang Founding Member

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    My MSD6A box had an intermittent problem. Usually the engine wouldn't start, but upon checking for voltage, I found the correct voltage at the right spots. Once it started, then the engine died after driving a few feet, then restarted again and made it home. It finally went bad when there wasn't any voltage coming out of the box. Being that my car is a street car, I have just bypassed the box. I have noticed a lack of crisp throttle response in the lower gears though without the box.
  5. 1badhrc

    1badhrc New Member

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    How often does cap and rotor go bad

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