holley ignition runs on

[redsmokin57]

I have a holley anihilator ignition and coil that when i turn the key off it runs on for a second. Have tried all the obvious things, diode on alt gen light, still does it with wires removed from alt, using pink original wire from hei as switched 12v, disconnect this wire and engine still has delayed stop, using green, black trigger wires to hei trigger, wires routed away from others, earth wires on everything, disconnect brown tach wire still does it, only time i can get it to cut cleanly when turning off is to unplug the main weather pack connector to the ignition. This has been happening for years, but I finally am getting around to sorting it out as it's not a turbo car and doesn't need a turbo timer stop to it. Pontiac 400 in 76 bird, with newly installed engine bay wiring harness. Any thoughts anyone?
cheers Steve

[Tuner]

Will it stop the instant you disconnect the trigger? If that works you could wire the trigger through a relay.

What distributor are you using?

Those are a crazy powerful ignition when they are used with an E-core coil.

[redsmokin57]

Using the stock trigger from hei with the module removed, will try unplugging the trigger to stop it. Yes using the holley street coil as well that plugs into ignition, could it be using the last of the power in the coil as it turns off?
cheers steve

[pamotorman]

twist the pickup leads so they are shielded

[Barry_R]

I am posting this message from my buddy Tim - he's the guy that accompanies me to every EMC I have entered.
About the best electrical guru you're ever likely to meet.

Steve, your troubleshooting procedure is spot on. The problem appears to originate in the box itself. You proved this by unplugging the 12V “key-on” wire from the box, and it still had the delay. If that Holley is like the MSD units, that wire only powers the small signal electronics within. The high power circuits are live continuously, right to the battery, and are enabled/disabled by that key-on signal. My guess is that the original designer put an oversize filter capacitor on that line, possibly to try to filter out contact bounce from the key switch?? Have you tried contacting Holley to see if they have a “fix”

Here is one simple test you can try. Bear in mind, if the box has a built in polarity protection diode(likely) in that circuit, this test will yield no improvement.

Temporarily connect a 12V incandescent test light (as a load) between the key-on wire and ground. See if it has any effect. If it has some effect, try a larger bulb, like a brake/turn signal type. This load is to try to speed up the discharge any capacitance in that circuit when you go key-off.

MR. Tuner’s clever relay idea has one particular land mine. The signal from the VR trigger is low voltage/low current, at least at cranking RPM. Trying to pass that signal reliably through a standard automotive relay would be problematic after the contacts oxidize. Not enough volts/amps to burn through inevitable oxide layer. It might work for a while…. I would use the “normally closed” contacts to short across the trigger, the failure mode doesn’t need a tow rope. In any case, You would need a “dry circuit” capable relay. Oh, and use a diode suppressed coil relay here, or you might find the reverse polarity destruction threshold of Holley’s key-on circuit. In Oz, you might check Jaycar? Electronics for such things.

FYI, those ISO cube relays can make over 600V back EMF at turn-off. Coil suppression vs release time vs load is a Subject for another post sometime.

Pamotorman has very good advice, alas that is not likely the problem here. Pick-up signal wires should always be twisted. Shielded and twisted (STP) is better yet, but ground shield at one end only. Run pickup wires in their own zip-code, better yet, foreign country. DO NOT bundle with other circuits.

Finding high temp shielded wire is tough. I’ve made it in short lengths by stripping RG-58 coax, and working the braid off. Tedious. Twist up some 20ga TXL wire and work the braid over. Heatshrink tube it.

Many moons ago, Fire Alarm Contractors had a use for STP that was 105*C rated, could look there. 10 ft pieces would be scrap to them.

Sorry to babble on, I don’t get out much…..

Tim Young

[tresi]

I had a bad brake light bulb do this to me once, If your foot was on the brake. The brake light filiment had shorted to the turn signal filiment and caused current to backfeed into the wiring horness.

[redsmokin57]

Thanks for the replies thus far, yes pick up leads are twisted and away as practical from other wires and plug leads. Disconnecting the trigger wires does give a clean cut to turning the engine off. And Tim thanks for the detailed reply, hooking a test light to the switched 12v trigger does not appear to do anything as the light goes out the second the key is turned off. It does as Tim has suggested run down as you turn the key off as though a capacitor is discharging. This unit was bought new back in the late 90,s and no longer produced so I don,t hold much hope of holley tech being of any service. I do have another unit exactly the same in my 57 chev that I could rob to try as when it used to be on the road it gave me no trouble, the only difference in set up being it used a crank trigger to fire it and it was bought at the same time.
Cheers Steve

[redsmokin57]

Go figure, swapped ignition unit for the one out of the 57 and all is fine! They were both bought from summit back in 98 by myself and a friend when on a holiday to the states and if I read the tag on the backs of the units right I would say one was serial no.000217 an no.000218, and maybe the build date 04497 not sure? Took the cover off the pontiac unit and not much to see as it, s potted in silicone. Oh well looks like the 57s getting a new ignition system, but still would like to know why it does what it was doing?
Cheers Steve