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Originally posted by markemark:

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Originally posted by David_D.: I have a fuse block that is powered directly to the battery, and a fuse block that is powered by ignition switch ON. Neither of those are through a relay. All of my accessories are triggered through relays.

I don’t understand how this is wired and would need to see a diagram to make sense of it. This being your design, you have more knowledge of it.

The statement below from your initial post is the part that is the most confusing and I’m guessing goes back to the Ign ON wiring method.

*Random instances of shutting the car off with the ignition switch and the car doesn't shut off unless I flip the master disconnect switch. Then it acts normally again.

This very well could be an issue with either the alternator wiring or potentially a bad relay.

Is this a street car that turned into a drag car and some of the street wiring/ fuse box still is being used? It sounds to me like your wiring method although working prior, is incorrect. Ignition On powering multiple relays is not correct. Ignition On supplies the +12v signal for “only” the ignition device to become active.

An inexpensive permanent fix to your problem and improvement to what you presently have could be as easy as installing THIS .

Update: after changing many things, I ended up unplugging the crank trigger and going directly from the ignition box to the distributor and everything worked. Apparently I’m getting some EMI from something at higher RPM.

Put a shielded pickup cable on.... the benefits of the crank trigger outweigh using the distributor.

I think it is about $125.

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Originally posted by David_D.:
Update: after changing many things, I ended up unplugging the crank trigger and going directly from the ignition box to the distributor and everything worked. Apparently I’m getting some EMI from something at higher RPM.

I have seen crank trigger sensors have this issue. I think they just break down over time. Just replacing the sensor fixes the problem, sometimes.

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Originally posted by CAD:
Put a shielded pickup cable on.... the benefits of the crank trigger outweigh using the distributor.

I think it is about $125.

I have a shielded cable. Swapped it and had the same problem.

Removed the alternator and the interference was better, but not gone.

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Originally posted by 1leg:

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Originally posted by David_D.:
Update: after changing many things, I ended up unplugging the crank trigger and going directly from the ignition box to the distributor and everything worked. Apparently I’m getting some EMI from something at higher RPM.

I have seen crank trigger sensors have this issue. I think they just break down over time. Just replacing the sensor fixes the problem, sometimes.

Replaced the pickup and still had the same issue.

Car has run quicker than it ever has plugged into the distributor, so even though it wasn’t noticeable, I’ve likely been having issues for a long time.

If you haven’t already, the 12v +/ - feeds for the ignition box should go directly to the battery not sharing wires with any other device. You can try checking the trigger wheel magnets strength with a paperclip. The paperclip should have the same amount of pull to remove when attached to the magnet. Sensor gap should be set to .065”. As I posted prior, consider a relay board and rewire.

quote:

Originally posted by markemark:
If you haven’t already, the 12v +/ - feeds for the ignition box should go directly to the battery not sharing wires with any other device. You can try checking the trigger wheel magnets strength with a paperclip. The paperclip should have the same amount of pull to remove when attached to the magnet. Sensor gap should be set to .065”. As I posted prior, consider a relay board and rewire.

I plan on running wires for the ignition box directly to the battery. I'll also check the magnets on the wheel for strength. I think my relay board is good, but I'll consider it.

Review and update:
I had a high speed miss that gradually got worse in a rather short period of time.

I changed every ignition component, with the exception of the magnetic wheel to no avail. I also checked all grounds, changed up some wiring, changed the master disconnect switch and tach. The only thing that fixed the issue was plugging the 6AL directly to the distributor and bypassing the crank trigger. I've been running it this way for the entire year and just decided to put the new magnetic wheel on to see if that was the issue. The miss was still there. Plugged the box back to the distributor and the miss was gone.

This is the most odd issue I've ever had and it has to do with some sort of electromagnetic interference, but I have not been able to isolate where it is coming from. I did eliminate the alternator from the equation and ran without the water pump turned on and the miss was still there.

What model # 6al are you using? Analog or Digital

Lots of good advise here. This reminds me of when my buddies car was acting weird and erratic. Turned out he had a high voltage wire near his distributor - caused interference with the pickup. Opposite of what your describing. I would reroute the crank trigger wires - even if temporary to try it out.

Also read my other post on grounds. Even if rewired - go thru every one and reconfirm they are good.

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Originally posted by David_D.: Car has run quicker than it ever has plugged into the distributor, so even though it wasn’t noticeable, I’ve likely been having issues for a long time.

After re-reading this entire thread I missed this post and think you could possibly have a polarity problem with the crank trigger wiring. Easy to check and verify if correct, but as I wrote previously one needs to know if you’re using analog or digital ignition (model # ? ).

With analog ignition the pulse is triggered rising, and in digital it is triggered falling.

With timing light, check the timing at idle and record. Swap the wire position in the cable connector and with timing light re-check the timing at idle.

Triggered Rising will be indicated by “least advanced” and Triggered Falling will be indicated by “most advanced” when viewing the timing position with light.

The pic is a patch cable I made to reverse the wires to quickly check the triggering device polarity along with a compatible pin extractor.

The easiest was to check crank trigger polarity is to look at the crank trigger pickup with a timing light. If the pickup and magnet is lined up you are good to go. If the magnet is 20 or so degrees above/past the pickup the polarity is wrong.

I'm using an analog 6AL with a 2 step module selector.

I've also swapped in my backup 6AL2 with the same results.

I've checked all grounds and swapped grounding points for the shielded cable as well.

I have a ground from the battery to a passthrough lug on the firewall and a cable from there to the frame and from the frame to the engine block.

The car ran fine for years utilizing the crank trigger. Yes it did seemingly pick up plugging directly into the distributor, however there are all sorts of other factors that could have lent to that other than just that change as the engine combination has changed over the years.

What has me baffled is there are so few components to the crank trigger and with the exception of the new wheel and the pickup, all were previously used on the car. Eliminating the cable, which also eliminates all other crank trigger components solves the issue.


The only electrical components on the front of the engine are the alternator and the water pump. I tested with the alternator disconnected as well as without the belt on the alternator. I've tested with the water pump off.

I tried a different cable from the 6AL to the pickup however that cable was not a shielded cable.

When you're talking about trigger rising and trigger falling, are you saying the car can run either way, however one vs. the other depending on digital vs. analog will run better?

Yes that is what he is saying. Check the timing and then reverse the green/purple wires from the crank trigger on the box and recheck timing. Which ever wire orientation is most advance is correct for a digital box. Most retarded timing is correct for an analog box. Also make sure the trigger wheel is oriented correctly on the balancer. There is a front and back. Msd marks them but it’s easy to miss the marking.

^^^^^^ This, 100%