Engine misses and detonates with mallory 685
 

Hi, with the stock ignition connected the car runs fine, but when I connect the Mallory Hyfire 685 ignition to the car it will idle okay, and drive around town okay, but whenever you put load on it the car wants to miss around 3000rpm and above and also will start detonating some when the revs get higher.

I just got this ignition back from mallory tech, because when i sent it off it was causing severe detonation under part throttle conditions just driving around town. I couldn't even get to 1/4 throttle before it started knocking.

The ignition is mounted in the spare tire well, wires ran across trunk to left side of car, wires run up driver side through fire wall, across valve cover, to coil, using msd harness at coil. Wiring is correct.

I'm just posting this wondering if anyone has ever seen this before and how you fixed it assuming it not the box itself.

Maybe your wiring going to your ignition coil is causing the problems. The primary is about 400V so if the insulation isn't up to it, then it might be leaking to ground through the insulation. You have some long runs of wire there...

Or it could be that the box is seeing too much resistance or something less obvious and that is causing problems.

Also, is your +12V good back there and good grounding? And is your engine properly grounded? You need a good power supply for that ingnition amplifier and the engine needs a good ground to make the ignition work.

You might try putting that amplifier closer to the coil and using some good wire to run to the coil.

relocated box to underhood near fuse box to see if it would matter. rewired with new connectors.

RUNS LIKE A CHARM, for now...

Kind of interesting to see we solved the problem without any idea what car, what year, what engine, etc......

Amazing - Nice work Kevin!