Sandy, I went on MSD's web site and found only the 4 pin listed. Maybe the 7 pin has been discontinued.

Sam

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input is 12v
output is MS and/or HEI

Leave the resistor out.


Biggest capacitor you have.

Don't you have one from when you were screwing around with the LC-1?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I think I know were those things are. When you say biggest, do you mean highest value? Highest voltage? Biggest physical size?I am really dumb about these things.

Sam

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Biggest MFD (uF)


Voltage rated 25V or higher.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Read this whole thread and dont understad 95% of it.Didnt read anywhere where the reluctor was trued up before it was gapped.Every one I have checked has high and low tips.I close up the gap and put a piece of 400 wet sandpaper with some wd40 on it and spin it till it gets smooth on all points.Useally takes 5 min spinning it by hand till i get the same drag on all of them.I allways start with a newly re bushed dist.Doubt this would fix your problem but had to throw that out there.Guzzi Mark

All Advice is welcome and thanked. You are right about the reluctor. The pickup itself is not exactly parallel to the reluctor blades. It is a little further away at the top. So that is on the list of possible fixes.

I talked to George last night for about an hour on the phone. Here is the current to do list generated by that phone call:

1.Twist "HEI to ECU communications wires to minimize possible interference from that end of things. Maybe shield it.
2.Turn on filtering in basic set up.
3. Clean up grounding by eliminating a chassis ground for the HEI, and take it directly to the block.

Thanks George.


Revelation.

I looked carefully at my pile of distributors and realized something rather startling about the Mopar units. The indexing of the cap to the body is done by the vacuum advance canister, which is removable, or in the case of the fixed, lean burn units, the steel block off plate that covers the hole in the absence of the advance diaphragm. This means that the process of phasing the distributor can be accomplished most easily by making a new block off plate with the indexing tab in the location of your choice to get the number one spark plug tower center over the rotor 7 degrees before the reluctor blade aligns with the pickup. This looks to be a much easier process than fiddling with getting the pick up plate locked down in exactly the right place.

Before I knew that phasing was an issue, I took a rebuilt advance unit and had the centrifugal slots welded shut. Then screwed down the plate so it would not rotate. As it turned out, it was in the wrong place, so I began looking for alternatives. Lou came to the rescue with his lean burn distributor which is what is in there now. Armed with my current knowledge, if I am still experiencing problems after all the above things are done, I will take this rebuilt, and home locked distributor and make a new plate to index the cap correctly, and try it. I will apply Madmax's tuning approach to it then.

Stay tuned. (Maybe get tuned first).

Sam

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Does twisting three wires together create the same shielding effect as twisting 2?

There are three wires in the bundle that goes from the HEI to the ECU. One of them is the bi-pass wire, which is the wire you unhook to time it. I can leave that one out, or twist it with the other two. Thoughts?

Sam

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OOps sorry bout that.......

Accel and Pertronix both have 7 pin modules available at Summit racing.

My MSD 7 pin module is probably 10 years old. They may have discontinued it.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I'm awaiting the results of the test run with the filter turned on.... I think he's out burning rubber right now.

Truing the reluctor... now there's an idea. Not for this problem, but for future tuning...

With three wires you could braid them... not trying to be funny there
Sam, you need to read my posts more Over in the distributor phasing I thread I talked about making an adjustable rod in place of the vacuum advance. Then you can set it where you want it. And it does not change the phasing. It's what I'm running now.



-G

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

Which of those two would you trust.?

Sam

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Sorry George, Do you have a link. I like to read the thread. Did you lock the centrifigal?

Sam

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I think it was actually in your distributor phasing thread. Yes, I welded the centrifugal.

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

Duh!

Here is the current status of things. Feeling good.

I have gotten it to run better but not by solving the underlying problem. I tried turning "on" the filtering, which also turns "off" the tach interrupt filter, and it ran much worse. You must put in a filter curve for this to work, and the values I tried just did not seem to work well. So, I switched back to the tach interupt filter and increased the value from 50% to 60%. I will explain what this does down below.

It ran much better for sure. So at that point I increased the filter value to 75% and it ran better yet, except when it went into miss mode, at a higher KPA and RPM, when it actually did the reset thing. So I took the filter down to 70%, turned on the autotune and drove for an hour.

By the time I was finished I was able to get it up to 4K at all KPA values below 130. It seems much more like it has a turbo and some power. I did not take it above 4 K at all. I actually got it into territory where preignition happened. So, I will begin figuring out the timing map, and get the water injection going again.

I first took it about 5 miles up a steady hill climb in 3rd gear,at 50 MPH, which kept it at 3K, and it took tons of fuel out. This was kind of uncharted territiry. Coming back home I drove the last five miles with it in second gear at 4K RPM which is about 50 MPH. It had never been in this part of the VE table up to now, so it was taking gobs of fuel out of the table. There is more of this kind of tuning to do. I am just glad I can get it to run well enough to drive it in those cells.

Here is the curious thing: as you drive in auto tune, a datalog type display rolls past. I do not know if you can re-play this. But the entire time I drove it, I never saw an RPM spike. However, thought I felt tiny misses as I drove. They were very subtle, and did not come anywhere close to melt down. I saw nothing in the scrolling datalog to suggest why. RPM was steady, AF ratio, MAP, etc. all stayed steady. I had the box checked to update the ECU as it tunes, so I suspect maybe I was feeling the auto burn as it happened. When I got back, I did not take it out for another drive so do not know if this little miss is gone with autotune off. (I really had to mow the lawn).

So, here is the deal. All VR signal lines are now twisted and/or shielded. All grounds are uncompromised, as near as I can tell. I have not put on capacitor filters yet, but likely will. Since it now runs well enough to drive it more aggressively in autotune, I can get the fuel dialed in, and once that is not an issue, I will take the filter back down to 50% and see if the signal is better. Maybe the noise in the line is somehow started by a fuel induced miss. Just a thought.

I suspect that there might be some cross talk that gets started between the HEI module and the VE pick up at certain frequencies. Peter is adamant that everything will work better if we can get this RPM signal cleared up. For now I think I have narrowed the spurious RPM signals to something happening in the distributor. Solving the RPM signal challenge is on the radar for sure, but not as hot a concern as it was a week ago. If I can get fuel and timing really tuned well, then solving the ignition challenge will be easier.



Here is the lowdown on the tach interupt filter:

The precentage you set it for determines how much time can pass between tach counts before a new one is accepted. It is the percentage specified times the time between the previous two RPM counts. In theory if you set it at 100% you could never accelerate the rpm of the engine. To figure out the highest percentage you could use, you could do the math of how fast you wanted to accelerate the engine from idle to redline. I have not worked it out, but it could be done.

Thanks to all contributors for their ideas. All ideas are now a part of my general grab bag of knowledge. Everything that was done was needed, and has made it better. I am feeling very encouraged. Sorry George, no burnouts yet. Eventually. Further thoughts are welcome, but as I get back into the ignition hunt, I think I will start a new thread. This one has gotten a little unwieldy.

Sam

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I am back to working on this. Things are gradually getting better, but still no cigar. The latest is that I reduced the tach rejection filtering to 20% and things got better. The miss is still there at 3500 RPM, but it does not reset. This is a big step forward. It just runs badly at that point but does not go into reset mode, with its associated back fires and complete loss of power for 10 seconds or so.

So, I sent a datalog to MAtt and he said the log showed there was a fuel-cut being triggered by the acceleration wizard tuning on the MAPDot threshold side of the control. Matt recommended raising the threshold way up from 100 to 999. This keeps the MAP controlled accel/decel from seeing noise and acting on it as if there was an actual MAP change. This can happen even when the control is set for 100% TPS controla as mine is. After the change it actually got better, but the noise, and a miss is clearly still there, and things still do not want to move smoothly through the upper RPMs. Whatever noise is there just does not have as many ways to cause mischief.

Then, a friend who is a real genius about almost everything mechanical and electronic suggested putting a ferrite choke in the main feed from the alternator to smooth out the current coming off it. So, I looked up ferrite choke on Digikey and they had scores of them, but at different values. So I am left scratching my head and wondering which one to get. It seems like it could not hurt, but I do not know which type to try. Max talked like almost any ferrite choke would to the job.

Max thought that since the break down always happens at the same rpm the problem is likely a spinning component like the alternator or distributor. He suggested, as have others here on this thread, maybe trying another HEI module.

Does anybody have a clue as to what spec ferrite choke to get and try here? He says that even though the alternator is supposed to put out pure DC, it will still show a slow, lazy sine wave, which could cause mischief at the right RPM.

Another thought: Do the injectors create EMI noise? This is a component that would possibly hit some critical frequency at 3500RPM and maybe set something off. There must be a coil in them.

I hope you guys have not grown totally tired of hearing about this. Your advise is not falling on deaf ears. I re-read this thread in its entirety every once in awhile.

Sam

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Injectors can cause noise--there is a coil inside them that actuates them.

Without the benefit of a good background in EFI systems, much less yours, I really don't understand your setup. But I have worked on some EMI issues. First rule is to gain distance between an aggressor signal and the victum wire. Remember how one should not overlap plug wires, due to crosstalk? Same idea. Shielding the wires can (and does) allow you to bring a noisy wire next to other wires; but separation can cut down dramatically on the noise. [In some applications I've had to recommend using steel conduit as a "shield". ]

I tend to be leery of adding capacitors to signals. The capacitor tends to slow down the signal of interest too; and depending upon what is making the signal, the extra capacitance can cause noise of its own (ie, the driver goes unstable). Sometimes though that capacitor is the right idea.

Grounding an electrical system is a huge box of worms; I won't even attempt to get into here. But, on your shielded lines, did you ground both ends? Generally speaking, on low speed signals, one only ties the shield to ground on one end, so as to prevent ground loops--which make noise of their own.

Hate to say it, but after working on these sorts of problems, I've usually wind up having to sketch out the wiring diagram, paying particular attention to grounds and grounding schemes; and then using a DSO (digital storage oscilliscope) to actually find the real problem... And then lucking out after a few hours of work.

Oh: ferrite chokes. Radioshack tends not to be the cheapest place to get anything electronic, but they do have some clamp on chokes. Might as well grab some. Easy enough to wrap around some wires. Depends upon what you are trying to choke off. Sometimes it takes multiple wraps around the choke.

But the altenator should be heavily filtered by that big ole lead acid battery. Given the magnitude of current out of it, I'd think a clamp on choke would be of minimal help: but it won't hurt to try. But I think you'll have better luck with the choke elsewhere.