Was that a typo? 12.8 running, 11.8 with fans? Umm yea, lets focus on this first as its a critical point before you consider anything to do with the interference. This isn't an interference issue. This is a current draw issue. 11.8 means the alternator is overwhelmed and your running off battery. It likely drops well below 11.8 but the laptop/MS just doesn't report it because it happens for a brief period (but can certainly cause the MS to reset no matter how brief, and engine to die/sputter/etc).

First, with engine not running but megasquirt on, measure battery and compare it to what you see in laptop. Should be minimal difference. If its big, the power wiring to the megasquirt (and any relays etc used) is suspect. Do same test with it running but nothing else on (lights, fans, stereo, etc). Then do same test again with everything running. Also get me voltage at the battery and MS while cranking but car not running. (Do not disable the megasquirt or anything else to accomplish this... how about just choke it off?) Stop monkeying with the HEI or anything else until we get this figured out.

Just to put it in perspective - with over 1kw (actual measured, not theoretical) draw from the electrical system, my voltage drops less then 0.1v @ the battery. Either your wiring or alternator is woefully inadequate.

Errr. you replaced magencore wires with nothing exotic belden wires to eliminate interference? That's a bit bass ackwards eh?

Why the msd at all? Is the HEI and blaster coil on its own not enough to ignite a boosted mixture?

Report back with the voltages. Anxiously awaiting, Sam.

You know more about this than I do for sure. But, the folks who know MegaSquirt seem to think this is a good idea. And, before I did this the engine would break down completely at 3K rpm. Explain what a ground loop is please.

Sam

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A ground loop is when current flows between one ground point and another in the same system. This isn't supposed to happen. Ground is ground, 0v, no potential. If multiple components in the same system reference the same battery voltage, but have a different ground, they effectively see different voltages. Sometimes this isn't significant depending on the application but this one certainly is.

A common place you may see it - in an audio system using a microphone, if the mic isn't grounded at the same place as the amp you'll get that humm going through the speakers.

Six months ago there were monster interference problems. Lou experienced it when here in May. The interference was a known and verified fact. At 3k rpm under WOT the laptop would register a sudden jump to 6K rpm, the ECU would deliver too much fuel and it would die, and then reset. So actions were taken to get that worked out.Many things were tried to get at the heart of the interference issues. Replacing spark plug wires with suppression wires was a shot in the dark at the time but one of many things that were tried, including using shielded wire for the pickup. Grounding the HEI through the ECU instead of to the block seemed to fix the bulk of the interference problems, so I quit fooling with it at that time and just drove it. Then last week something new cropped up when it died on the way to work. So now we are on to a new, and maybe just as basic problem. I am glad you have been able to pinpoint something here that is going to move us forward.

That being said, please don't jump all over me or call me names for doing dumb things in the past. You can think those thoughts if you must, but just don't type them. They are not helpful at all in any way shape or form. I was usually taking someone else's advice, and always doing the best I could. I have admitted many times I am pretty dumb about this stuff. And you are much smarted than I am . So, be gentle. Let's move forward. I am eager to get this fixed, and you can help I am sure.

I don't have much time in the next week to fool with it, but will do exactly as you say sometime soon. My VOM is acting up, so I will have to either replace it, or get this one fixed somehow. For what it is worth while it is running the voltage gauge on the dash measures 14. volts or so while the lap top shows 12.8. I do not know why the difference. I assume there is an internal regulator, but maybe there is a drop somewhere between the battery and the ECU connection.

Sam

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I see, that is helpful. Thanks.

Sam

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I agree that the voltage should not drop anywhere near 11.8 with the fan on. I assume the fan has its own relay and is powered by direct battery voltage? Need to fix this first.

Lou

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Home of Slant6-powered fun machines since 1988

Fan has its own relay powered by direct battery power. Yesterday I realized my old VOM is giving me false readings. I cannot continue working on this until I get that worked out. The old one I have used for years is reading about 5 volts too high. It was showing 19 volts at the battery while running, while the meter on the dash showed 14. I have another one that needs a battery right now. When this is resolved I can continue with readings to figure out what is happening. At that time I will post a chart of volt readings at all junction points in the system, both running and not running.

Of course if the car will not start, then the pickup issue becomes the highest priority. There is a serious deadline at work that is actually a higher priority at the moment.

Sam

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Hold on a minute...

Question: Is it possible that we are all "over thinking" this?

The original problem, if I read it correctly, was that the car dies when the electric fan comes on. Is that still the case, or is the car dying all by itself, even with the fan relay disconnected?

If it's still happening only when the fan switches on (or off), then disconnect the electric fan relay and drive the car.

If all these issues go away, then great... we have one area to work in... which is stabilizing the voltage in the vehicle and / or limiting the RFI that the fan or its relays are generating.

If the car STILL dies with the fan disconnected, then we must go deeper into ground loops, shielding, faulty pickups, overheating components, etc.

- Mac

BTW - Please don't think that I was criticizing you for connecting the ground for the HEI through the ECU. I can see that as a potential problem area, but that doesn't mean I think that you were off your rocker to do it that way. I'm just trying to run through all the possibilities.

I did not infer any criticism on your part. Thanks. The car died even with the fan off. I was playing with the fan thermostat in attempt to watch the effect on the voltage, and it died with it on, and with it off. So I think there are different issues here . Both are important apparently.

On the other side of the coin, don't hesitate to tell me something is wrong. That will not hurt my feelings. Just don't call me dumb for doing it the way it is right now. I have no pretenses about being MR Cool, or of knowing everything. Some folks use forums to puff themselves up, and look good. I obviously do not do that. I kind of expose myself to ridicule on a regular basis. There is obviously room for improvement, and I want any advice available. But just be kind about it.



Thanks.

Sam

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That's good Sam. It sounds like you do enjoy the "learning" process in the end. You will get to the bottom of it and then you will feel good about it! I also show my own dumbness many times. Electrical things are just confusing as all get out to me. You should feel good, because you are still light years ahead of me in "smarts" department.

Good luck my friend!

PS. I still want you to come to Mason Dixon and race (I mean test drive) with us!

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

My bad Sam, never intended on any harm, was just a head scratcher about the plug wires.

The fan is only exacerbating your under-current problem. Even 12.8 with the fan off is low. It's not the end all be all low that 11.8 is, but it is suspiciously low. You should be in the high 13's to low 14's load or no load.

The car not starting and not reading any rpm - I'm starting to suspect that's not a megasquirt or pickup issue. Gap the pickup and be done with it. They are pretty simple devices by nature. If they work they work, if they don't they don't. Usually no middle ground if its gapped right. If line voltage is too low things simply just won't function. Your starter draws more current then the fan does. If the fan drops voltage to 11.8 running (who knows how much at the peak instantaneous turn on point) your starter could easily be dropping voltage to the point megasquirt won't function. That's why I asked for all the voltage readings.

BTW - Unless your meter has sentimental value getting it fixed isn't very cost effective. Fluke brand is still sold at Sears. Top notch stuff. Their basic models are in the low 100 range.

We were responding at approx the same time as I edited my last message so you may not have seen my update - why the MSD box at all?

Checking reluctor gap is a great idea. TWO racecars at Bristol this past weekend were having ign trouble because their dists were gapped too loose.

Lou

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Home of Slant6-powered fun machines since 1988

Am I correct that the reluctor itself has a little magnet "voltage" of its own? And that the reluctor could be bad itself. Is there a check for them?

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

The reluctor can't go "magnetically bad". It can be physically damaged, but that's the only failure mode.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Any magnet, including permanent magnets, can loose their magnetic properties. However, it would take a super long time, or incredible temperatures, improper handling, etc to do it. There is a spec, if you spin it at x rpm it needs to put out y voltage. Thought I ran across it in the FSM. But that's not what's happening here. Another all or nothing type of deal.