Mid-high RPM ignition cutout

[Rchab]

Okay for starters, I've got a 69 charger 440 with the Proform mopar electronic distributor and Holley Sniper EFI. Everything works as it should up until I stomp on the gas. The car pulls up until about 3500rpm to where the car starts jerking terribly. I got a datalog from my sniper system to show what's going on and I'll link it. The rpm data shows it climbing then dropping drastically and back up to correct rpm multiple times. So far all I've got to go off of is a couple people in the sniper forums don't believe it's the efi system causing problems, and noted that the rpm signal varies unusually throughout. Could this be a coil problem or something going on with the distributor?

 

[Rick@Laysons]

You might check your battery for a dead cell.....even if it's a new battery.

Ran into this with several vehicles over the years.....

 

[Rchab]

Just before cold starts when I check I'm at 12.3V so I don't believe the battery is bad. Charging is fine as well throughout the rpm range

 

[dadsbee]

12.3 static is not a "good" battery...

Where do you have your power connection for the EFI as well?

 

[hunt2elk]

Just before cold starts when I check I'm at 12.3V so I don't believe the battery is bad. Charging is fine as well throughout the rpm range

Should be 12.6 I believe.

 

[Rchab]

That's usually where my batterys have sat over the past 3 years from restoring the car right at 12.3-12.5V. Went through a battery from a bad alt messing up the first one. I've got the + and - for the Sniper going straight to the battery posts

 

[dadsbee]

Have you got one of those Noco hand sized boosters? Snap it on, tuck it beside the battery and go for a boot!

 

[Rchab]

Have you got one of those Noco hand sized boosters? Snap it on, tuck it beside the battery and go for a boot!

Just a little jump starter? Yea I could hook it up and try, might have time for that tonight even

 

[dadsbee]

Just a little jump starter? Yea I could hook it up and try, might have time for that tonight even

Yes, it should at least rule out a battery / voltage issue... or prove that it is one!

 

[Bee1971]

Not familiar with the Sniper system on my own

Doesn’t it require its own distributor and ignition system based on the EFI , correct me if I am wrong

Anyways with the Proform distributor , what are you running for an ignition coil and ignition box ?

And you are required to bypass the ballast resistor , full 12-14 volts with the Sniper system correct

 

[Rchab]

Not familiar with the Sniper system on my own

Doesn’t it require its own distributor and ignition system based on the EFI , correct me if I am wrong

Anyways with the Proform distributor , what are you running for an ignition coil and ignition box ?

And you are required to bypass the ballast resistor , full 12-14 volts with the Sniper system correct

It's not required, you can still run it with the "factory" distributor, just can't control the timing via the sniper system. For the ignition box I've got the orange box that came with the distributor and for a coil I have the "ACCEL 8140C Ignition Coil" that I put on in 2020. As far as bypassing the ballast I'm not sure about that? I thought that'd mess up the ignition system in general if I bypass it so never thought to check. Never saw anything in the manuals about it as I was putting it all together

 

[Rchab]

Yes, it should at least rule out a battery / voltage issue... or prove that it is one!

Tried it and nothing changed, still not liking the rpms

 

[RJRENTON]

Tried it and nothing changed, still not liking the rpms

Looks like you have a bad ground......or.....it's time for a new car.....or .....it's the Accel coil incompatibility with the rest of the ignition syndrome.....try a different coil......
BOB RENTON

 

[RemCharger]

Any resistance in the wiring to the coil will give these results.

 

[Bee1971]

Ignition Coil or Orange Proform ECU Ignition Module

With all the Chinese aftermarket Mopar ECU Ignition Modules made today , honestly I can’t even recommend a decent replacement

But one or both of those are just about 100% your issue you are describing

 

[Under Pressure]

Don’t know much about snipers, but it sounds like mine 2 years ago, ECU died, I bought new one, car fired up but acted like it had a rev limiter, couldn’t get rpm’s over 3,500, went to a friends and put his orange box on and it was fine.
Vendor replaced it, no issue since

 

[RJRENTON]

Ignition Coil or Orange Proform ECU Ignition Module

With all the Chinese aftermarket Mopar ECU Ignition Modules made today , honestly I can’t even recommend a decent replacement

But one or both of those are just about 100% your issue you are describing

The alternative to Chinese stuff, is to revert back to points and a recurved distributor...works every time all the time and will go to 6000 RPM without issue....and all your buddies will wish they did as well.....
BOB RENTON

 

[threewood]

If you have the parts, get it back to points, set dwell and take it for a ride.

We have a few members that can look at a saved data log and give you suggestions.

 

[Rchab]

Ignition Coil or Orange Proform ECU Ignition Module

With all the Chinese aftermarket Mopar ECU Ignition Modules made today , honestly I can’t even recommend a decent replacement

But one or both of those are just about 100% your issue you are describing

I'll start with the ECU since ive had the coil for a while now and I don't believe it had this problem before I switched over to the electronic distributor + components...now to figure out which replacements worth a damn

 

[dvw]

The trace looks like it's on a rev limiter. There is no way a fuel issue could be that quick. I'd say you have a distributor or ignition box issue. Though I never discount the idea of a bad ground. In this case I don't think so. Doubt its a coil either. Why? Because it's rpm triggered. One other posibilty. The tach. Does it have a rpm limiter? As for the battery. 12.66 is 100% state of charge at 80 degrees F. If the temp varies so does the state of charge level. My bet is it's fine. See here
Doug