Holley hyperspark

[Hspencer]

Ok all you ignition genius’s I have a hyperspark question.

I’ve been running the Holley sniper 2300 for a month or so and decided to add the hyperspark distributor, ignition module and coil. After the install and setting adjustments it starts up and runs great, got it up to operating temp then went for a drive. Runs great no stalls or hesitation and timing is being controlled properly by sniper. The issue is I have engine run-on after ignition switch is turned off. There is a wire from both the module and distributor that requires 12v start and run position, I have these connected to the yellow wire that connects to the original ignition module which is now unplugged.

I assume it’s getting some residual voltage that’s keeping the module energized. I was thinking maybe a diode on the yellow wire but don’t know enough about it to know for sure.

Any thoughts or suggestions would be greatly appreciated.


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[tgreese]

No downside on adding a diode in the module or distributor wire. When you add stuff like this aftermarket ignition, it can be difficult to isolate the path of the back-feeding to the ignition switch.

Note that the alternator exciter connection stays high with the engine running, and this is connected to the ignition switch. Normally there is a resistive wire (single-strand nichrome wire) that is enough resistance to stall the conventional coil and module supplied by the factory when the ignition switch is off. Look on the factory wiring diagram for the resistive wire from the under-hood harness to the alternator. This wire may not be sufficient to strangle the Holley ignition. If this Jeep were mine, I would replace the resistive wire with a conventional stranded copper wire with a diode in the middle. Place the diode hidden in the harness and immobile, since any flexing will fatigue the diode's solid wire leads and they will break.

[Hspencer]

Therese, was a resistance wire used in 88, I know my 84 had it but wasn’t sure about the 88. Any recommendations on proper diode to use?

I did speak with Holley tech and they recommended putting the 12v switched wires on a relay, not sure if that would make a difference


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[acct21]

It's two ways of achieving the same result -- killing power to the ignition when the key is shut off.

Your easiest solution is to do what MSD recommends if you get run-on with their 6AL ignition box -- put a 1A-100V diode inline on the smaller of the two wires entering the plug on your alternator. If you search on "MSD 6A diode" you'll find the instructions in the www...

[tgreese]

I looked at the '88 diagram on the Tom Collins site, and there is a resistance wire to the alternator. You understand this is different from the resistance wire to the ignition coil? The resistance wire to the coil takes the place of the ceramic block ballast resistor used in earlier years. The ballast resistor is meant to limit the current to the coil and has no effect on back-feeding.

The MSD module uses a separate power feed to the module. The coil wire is only used to turn the module on and off. The heavy wire to the MSD is hot all the time (going directly to the battery), and the module on-off depends on the coil wire. I don't know how your Holley ignition is wired up, but if it's like the MSD, there's no path to back-feed.

A relay is usually used to handle the heavier current load you might need for the new module. A relay could stop the back-feeding problem if the circuit is backfeeding through the main power feed, but I suspect that's not the problem. The existing Duraspark module power wire should be sufficient. The Holley tech likely does not understand that you are using the power wire from the Duraspark module to run the Holley module. This should be sufficient to power your Holley ignition. Again, if it turns on and off by the ignition switch, it's not controlling the ignition power, but being controlled by it.

You can test whether the relay would make a difference by purchasing a relay and connecting its coil (not the contacts) to the ignition. https://www.parts-express.com/12-vdc-wa ... t--330-079 Ignition on, relay closes (test with your multimeter). If the relay then opens when you turn off the ignition and the engine keeps running, it likely will help with the run-on. If not, it's going to do nothing.

Another easy test would be to disconnect the alternator and start the car from the battery. You'll need to pull the plug out of the back of the alternator, and remove the big red wire. Careful with those wires - they are connected to the battery, so tape them off and put them out of the way. If the Jeep shuts off with the alternator disconnected, you've found your problem.

To pick a diode, just make sure the voltage and the current rating are more than what you need. For example, this diode https://www.allelectronics.com/item/d61 ... ode/1.html would be fine for anything under 6 amps like the alternator connection.

[Hspencer]

I’m out of town at the moment but I’ll do some testing when I get back and let you know.

Here’s the wiring diagram which is how I have it wired. I’ve been disconnecting the points output wire from the sniper to shut the engine off.




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[tgreese]

It's interesting that the distributor is connected to the throttle body. Does the module shown above control both fuel and spark? I'd presume it does.

This diagram suggests (to me) even more strongly that the alternator wire is your problem. The module has a connection to the battery which would supply the majority of the current to operate the electronics and the injectors. The connection to the ignition switch is probably a logic-only connection to the module, distributor and throttle body. Addition of a relay coil as an additional load might be enough to shut the module down, but adding a pull-down resistor should be just as effective. If the relay coil draws 20 mA, then a 500 or 1000 ohm resistor from the ignition to ground should have the same effect. I'd do the diode first. Simple, effective.

[Hspencer]

Yes, the throttle body controls everything. This is the main reason I went with the Holley system over the Howell system. Everything is under the hood, no ECM to find a suitable place to mount in the cab.

I’ll order the diode and hopefully it will there when I get home. I’ll keep you posted.

Thanks for all your help and input!


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[tgreese]

NP! Glad I could help. Interesting topic.

[Hspencer]

Tgreese, I received the diode yesterday and got it installed on the resistance wire from the alternator. Worked like a champ, no more run-on and no issues with exciter wire doing its job. I have read where some folks had issues after a diode install with idiot light staying on or needing to rev the engine to get the alternator to start charging, I’ve had no such issues.

I didn’t have time to completely change the resistance wire but will do so in the future. I looked at the oljeep schematic and it shows a yellow wire from the alternator but had resistance wire penciled in, do you know where the other end of the resistance wire terminates?

Thanks again for all you help! It’s nice to have good folks with lots of knowledge willing to help out a stranger. I wish that was still the standard and not the exception!


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[sm023595]

Hello, not sure if either of you are still active as this is an old thread but I'm having the same issue as described above. holley sniper EFI with hyperspark on an 89 wagoneer. Key off and engine stays running.

I'm far from a wiring expert but it looked like a diod resolved your problem. I follow the link provided above to the diod and had a question. How the heck do you wire this thing, i've never seen anything like this.

https://www.allelectronics.com/item/d61 ... ode/1.html

I see a lot of different diod's at the local part store that look way different that is pictured in that link. Can I get one of those?

Thanks!

[tgreese]

It goes in series with the alternator exciter wire. By convention, current flows from the anode (+) to the cathode (-). The end with the line is the cathode. This end goes to the alternator side.

Whether your diode from the parts store will work, I don't know. The diode I linked to is a common-as-dirt type used in electronics. It does one thing - conducts in one direction only - and has a voltage and current rating. The parts ratings must meet or exceed your application. Post a picture of the diode you want to use.

[sm023595]

Thank you, so judging by the wire diagram, I just splice it into the resistance wire coming off of the alternator?


I did find this little diode that looks a little easier to tap in, from reading the specs it looks like it should work.
https://www.amazon.com/Painless-80111-D ... ive&sr=1-1

[tgreese]

You need to put the diode between the alternator and the ignition. Between B7 and 78. The alternator will hold that wire at 12V as long as the engine is turning. The diode allows current to go to terminal 1 on the alternator, but not back to the ignition switch.

Sure, if you want to pay $13 for a 35c part. No problem

[sm023595]

Thanks for the reply! it's more of a matter of getting the part asap. Love some amazon prime it should be here today, the other one would be over a week

Appreciate all the help!

[tgreese]

Happy Amazon stockholder, me!