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Bad Break up(Resets,Grounding,Noise Problems)


jeffer949

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Well I got my Magnecor's in today and installed.. And well lets just say i went for a ride and there was alot of cursing going on because its still Resetting.

 

Im so lost on this car. I cant find anything wrong on the megasquirt. And i have to drive around with my laptop at all times so i can reload my firmware about once a day on average when im out driving it.

 

Im this close to lighting a rag in the gas tank. I just dont know where else to look.

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lets think around MS. hows your dizzy cap and rotor? fuel pump? fuel filter? stock fuses? fuses in you MS wiring. Or?? how about your ignition switch? do you have any stock relays, or check all your relays?

 

I feel your pain.

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Jeff read through this:

http://en.wikipedia.org/wiki/Electromagnetic_Interference

 

"EMI or RFI may be broadly categorized into two types; narrowband and broadband. Narrowband interference usually arises from intentional transmissions such as radio and TV stations, pager transmitters, cell phones, etc. Broadband interference usually comes from incidental radio frequency emitters. These include electric power transmission lines, electric motors, thermostats, bug zappers, etc. Anywhere electrical power is being turned off and on rapidly is a potential source.

 

My thought is, if it is happening now, maybe you've moved your plug wires around (bumped) and now they are causing the issue.

 

When you cut the harness did you move anything else?

 

 

Is it just me that noticed this or does Megasquirt seem to have an inherent problem with EMI? I've read about several problem MS installations that exhibit similar symptoms. The recommendation is often "fix your EMI problem". Why don't other standalone EFI manufacturers have a similar issue? I don't mean to thread jack but the EMI issue comes up often.

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My hunch is that because so much of the wiring and assembly is open to the user's skills, there is lots of opportunity for error in installation and wiring.

I'll add that the routing of sensor wires can play a role in allowing noise to creep into the MS system. Most people focus on the power and ground wiring, and that's important, but EMI can affect any wiring, and long straight runs are quite susceptible (they act as an antenna!). One good practice is to twist the pairs to/from the sensors, or even to switch to shielded cabling. I'm not saying that will solve the issue in this case, just saying that eliminating EMI is tough and involves a variety of best-practices.

 

Jeffer949, where do you have the MS unit mounted? Is the cover on it? Where is the relay board mounted (if you used one)? Do you have any of your wires running near the ignition coil? How about near the spark plug wires (aside from where they cross over valve cover - or did you route them some other way)? Do any of your wires run across openings (free air) as opposed to following along the metal of the car? Just throwing some things out there to look at.

 

It's one thing to have resets, quite another for the MS firmware to become corrupted and require a reload. At the risk of stating the obvious, something is still quite wrong here.

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Is it just me that noticed this or does Megasquirt seem to have an inherent problem with EMI? I've read about several problem MS installations that exhibit similar symptoms. The recommendation is often "fix your EMI problem". Why don't other standalone EFI manufacturers have a similar issue? I don't mean to thread jack but the EMI issue comes up often.

 

I'm thinking it may not be related to EMI. It may be, but he's removed his wiring from the Alt and still getting spikes and replaced the plug wires to Magnacor w/ the same results. He's never had a problem until recently.

 

I'm curious if removing the belt all together and not spinning the Alt will help at all, if EMI is suspect. Other than the coil and maybe the MSD box, what else is putting out high amounts of current on and off rapidly?

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It's one thing to have resets, quite another for the MS firmware to become corrupted and require a reload. At the risk of stating the obvious, something is still quite wrong here.

 

You guys have probably seen some of my posts in the past about one of my friends TPI installations that continually gets resets to the point that the firmware has to be re-loaded just like stated above.

 

Some of this has been posted before, but some of it is new:

 

We had found that his processor chip was not seated all the way in the socket on the megasquirt board, that helped a little bit.

 

Since then he continued to get resets and firmware corruption to the point that he gave up and sold the truck to another one of my friends that has more experience with cars and megasquirt, then:

 

I looked over the entire setup and didn't like several things about it, there were not good grounds across the entire vehicle. I suggested to add big ground cables from the engine block to the frame, add smaller ground cables from the engine block to chassis, add better ground from MS relay board to chassis.

 

After that the resets got better again, but not fixed. My friend then noticed that the relay board was mounted in a position that caused the exhaust to heat it up a bunch, when it got really hot the resets started. He swapped out relay boards and also moved it away from the heat source. So far this has fixed the reset and corruption problem.

 

The PO had used super human strength to push the fuses into the relay board and had totally busted the sockets. I believe he had also damaged the internal traces of the circuit board by pushing so hard he flexed the board itself. The heat cycles then causes power traces to start opening up making for all kinds of trouble.

 

Just some more stuff to think about since it seems like a weird one. All I can say about this installation that had resets vs all of my other installations that run fine is that virutally everything was done in a hack job manner. Grounding between battery/engine/frame/chassis was non-existent. Stuff was so messed up that the LC-1 that was installed ended up going bad, no idea what is wrong with it but it is dead now.

 

In general there is no such thing as too much grounding. Having at least one condenser near the coil is required. Resistor plugs and resistor wires can save the day. Make sure someone did a good job soldering your MS board. I know all of this has been mentioned before, but it never hurts to mention it again.

 

Good Luck

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I just took apart all my wiring on my car and did everything with twisting of all wires to sensors and such. My relay board is Under the drivers inspection panel is. I built my whole unit and ive had it out several times and all my solder joints look great.

 

One thing i dont have is a condenser on the coil. How do i wire that up? Also when i had my alternator unplugged I noticed i didnt have one on there either. Not sure where it went.

 

Im going to go take it for a test drive and see how it does. Ill let ya know.

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The condensers are capacitors and they go between 12volts and ground. I always have one at the coil positive. I have spent some time measuring noise on the 12 volts systems and the most seems to come from the coil or coils, the alternator and the injectors. Keep at it, these kind of problems will force you to learn about parts of the system you never wanted to learn about.

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Ideally you'd find one off of an old Z such as the cap that's next to the distributor or the one attached to the alternator. I'm not sure of their exact value, but you could also pick up an electrolytic capacitor at Radio Shack. Probably go with a 100 uF rated at 100V. Or maybe 50 uF? I'm not sure what Nissan used, but the exact value doesn't matter as much as you'd think. The cap is basically acting as a short circuit to high frequencies and an open to DC. Smaller values have more effect at higher frequencies.

 

Anyone know what values Nissan used?

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I have one on my alternator, but not at the coil. I think I have an old one or two hanging around? Do I go from the 12+ on the coil to the capacitor then to ground?

 

On my alt. I think its hooked to the ground wire then bolted to the alt.

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K well i cant find any caps that im used to seeing. Maybe ill hit a junk yard tomorrow and just snag some from different vehicles. The car is becoming almost undrivable. Its getting more to where If I take it up to 0 psi it just starts to break up horribly. I even thought maybe my turbo was locked up and wasnt allowing any air through so i took my filter off but its fine. Can the map sensors go bad and cause a problem? Do they go bad if you spike over the max value of them? I might see about ordering a new relay board pcb board as its pretty cheap and just transfer all my componets over to it. Im so lost on this its not even funny.

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I've been going on the assumption that your issue is due to resets. But you used the term "break up horribly" again. Without trying to pick on your words, I'm wondering if you've got something else going on. Have you taken a datalog and looked at your spark advance and injector PW values while the break up is occurring? If there's a problem with your MAP sensor I would expect to see that show up too.

 

Perhaps you can post the datalog and let us know what times to look at?

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Hey Jeff,

 

Got your message and didn't get back to you -

 

3 things come to mind:

 

1. Grounding - make absolutely sure that the ECU, MSD,WBO2, car chassis, and Battery negative ground points have less than 0.1 ohms difference between them.

 

2. Closely examine data logs for anything weird that might point you in a particular direction. I agree with those that say this problem is most likely caused by noise, whether it be radiated EMI or power supply induced.

Look for anything weird - steps, spikes,etc happening on sensors or battery voltage - anything that may point to a specific direction instead of checking everything and flying off on tangents. Pay special attention to battery voltage and MAP sensor. If nothing conclusive shows up you may have to swap in a known good ECU.

 

3. Your symptoms are consistent with high voltage arcing causing EMI. Replace your distributor cap and rotor. If possible, swap in another coil. Try running without the MSD. Try that old trick of looking under your hood with the car running in the dark and checking for visible arcing. I've seen bad MSD coils arc at the high voltage tower.

 

Oh yeah, Ford EDIS coils have a 25 microfarad, 50Volt electrolytic capacitor connected from the + terminal of the coils to ground. You can get something close to this value at Radio Shack (20- 50 microfarad will do). Mount the capacitor as close to the coil as possible. Note that electrolytics are polarized - connect the cap's + side to the coil +.

 

I'll try to think of more...

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