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Serious Question

Posted: Sun Oct 13, 2013 10:17 am
by neckstrap
I have just purchased a new hard rev limiter PCB and have been studying the instructions. There is one thing that worries me. According to the instructions, I am supposed to remove the connection that goes to the coil pack's center pin from the EDIS ECU and connect it to the MegaJolt rev output pin. It seems to me that this may make my system less reliable.

I run long distance rallies though remote areas of California. One of the reasons I converted from the distributor to the MegaJolt is to improve reliability. I carry a spare EDIS ECU and coil pack "just in case". However, I do not have a spare MegaJolt. I have not worried about this because the EDIS "Limp Home Mode" is not bad at all and the car runs pretty good with it at cruising speeds.

So, IF I install the rev limiter board and move that wire to the MegaJolt's connector and IF the MegaJolt main board or Rev Limiter PCB were to fail, would I be stuck in the middle of nowhere without a "Limp Home Mode"?

Please let me know,

Posted: Tue Oct 15, 2013 10:59 pm
by brentp
Like with any system, there is a finite possibility of failure. With the Rev limiter supplying power to the coil pack you will want to make sure the power connection to the megajolt is sufficient gauge and current (15A fuse).

If something does happen and the engine is disabled, you could engineer a terminal quick release to switch it directly to a fused source. That way you won't be stuck.

Let us know how it works out (and if you do actually get stuck!)

Posted: Fri Oct 18, 2013 12:42 am
by neckstrap

Thank you very much for replying and verifying my concern. I came up with an idea. I will put a switch in between the coil packs, the fused +12 and the Megajolt. With the switch in "Rev Limit" position, the Megajolt will control the coils. With the switch in "Limp Home" position, the coils will go directly to +12 volts.

I know that you may think this is overkill, but it is no fun investing hundreds of dollars in entry fees, gas, hotel rooms and car preparation, then have to sit in a broken car for hours waiting for a flatbed truck. Believe me, I have been there and done that!


Posted: Fri Oct 18, 2013 12:55 am
by brentp
Got it. If you can stand the hassle of having to pop the hood to switch a quick connect terminal from one to another, I would forego the switch and use a quick connect terminal for the following reasons:

- the switch itself is a point of failure (seriously, I've had them and relays go bad)
- you won't have to run lengths wire to and from the cockpit dash
- less work to implement.

Just a suggestion.

Either way, please do post here again if you ever experience the failure you're protecting against!

Posted: Tue Mar 15, 2016 10:25 pm
by parky1972
Old post I know.
But this may be of use to others.

On my loom I have made a bullet socket connection into the 12v wire from the megajolt.
I also have a matching bullet connector on the coil power pin from there megajolt.
I run the wire from the coil pack to this point with a bullet connector on.
This can be plugged into either the coil pin on megajolt. So the rev limiter is being used.
Or, if I move the wire to the 12v bullet connector, I have constant voltage. Should either the megajolt unit itself oir the rev limiter board die.
This way, I still have the option of getting home on edis alone should the entire megajolt board go down.


Posted: Tue Jun 05, 2018 5:32 pm
by neckstrap
I wonder if anyone still reads this forum, but here goes.

I just installed a Holley Sniper EFI system and had to go back into the Megajolt to make some changes. I have learned a few things:

1. I bought spare Megajolt on eBay and have been carrying it around for all these years as a backup in case the first unit fails. After reprogramming the primary, I changed the program in the spare to match. But, when I tried to start the car (with the spare installed), it would not work. I had forgotten about the rev limiter that I had installed in the primary unit. The spare does not have the rev limit pcb and will not work without the same connections.

2. I am planning to run a long rally and the hard rev limiter kit does not seem to be available any more?

3. Saw Brent's and Jason's posts and will wire up a bypass as suggested. Thank you both very much!

Posted: Tue Jun 05, 2018 5:36 pm
by brentp

Correct, the hard rev limiter add-on board is no longer available, sorry.

Re: Serious Question

Posted: Fri Apr 29, 2022 11:13 pm
by jlouviere3

How did you connect the rpm wire from the Megajolt system to the Sniper???