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Edis Misfire/random Reset Troubleshooting


Rocan

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I've been chasing this issue for a little while now. Car ran fine for most of the winter, then at some point a slight miss started that has progressively gotten worse. I have narrowed it down to being an EDIS issue as the problem exists even with the megajolt unplugged. 

 

First I thought it was my absolutely horrible negative ground, which was broken and corroded. Changed that so everything is nice and tight and nothing changed. Replaced the worn coil with a new coil that accepts my pretty kingsborne wires, so the coil pack, plugs, and wires are new. Plugs are resistor type. 

 

Now, I am not happy with my edis wiring. It was rushed and I am in the process of redoing it; I have a new connector plug from millers mule ready to be installed, plenty of wire, connectors, etc etc. But I can't find a specific reason why my current wiring would work perfectly well (surprisingly well!) in the past but not work now. 

 

While digging around, I noticed my 12V feed for the coil went to crap. It was taped up and had been poorly crimped at some point (not my doing; I wouldn't have let that stay there if I knew it was like that), so I guess things got hot and the tape inside melted to form a rubbery gum. AHA! I thought, and I made a fresh connection with proper heat shrink and a proper crimp. The issue improved dramatically, but it's still there. It's at least drivable now, but while on my testdrive I got a random reset which killed the engine. Started up right away after. 

 

The misfire is present at idle, but not nearly as noticeable as when held at constant revs. It misfires almost every 4 seconds. I have read about placing a 25uf cube capacitor onto the coil feed line, but I cannot find a suitable one that doesn't cost 80 dollars; no way I'm spending 80 bucks on a capacitor. 

 

I will be redoing the Megajolt/Edis wiring completely, but in the meantime I want to figure out I'm having so many troubles. Any ideas?

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

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I'm not mechanic, but I can tell you that your problem is close to what I'm experiencing.  A refresh of a few of the ignition components made the problem subside, but it's still there.  Mild, but there.  Not noticeable while driving at all.

 

I don't know what EDIS means (Electronic Distributor Ignition System?) but my distributor is mechanical with contact points.

 

Never heard of "25uf cube capacitor" what's that?

 

So, bad grounding cable could cause this problem?  My ground cable looks good to me, but I'll double check.

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EDIS: Electronic Distributorless Ignition System... It fires off of a signal taken from the crank. Far more accurate than a distributor could ever be.

 

Electronic ignition systems are extremely sensitive to grounds. Poor grounds can cause all sorts of running issues. Poor grounds are bad for everything, period. Just fix them and make sure things are grounded properly. 

 

25uf cube capacitor is just a 25 microfarad capacitor, but it is cube shaped and is a bit more durable compared to your standard capacitor. They came standard with all the vehicles that run an EDIS system, which makes you think finding a replacement would be easy, but I can't seem to find one. 

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

A bunch of Bikes...

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If I read everything correctly, the only thing you have not changed or adjusted is the VR sensor . Check the gap between the trigger wheel and the sensor. If I remember correctly, it should be .02" to .04". Make sure there are no metal chips or filings at the end of the sensor. BTW, the capacitor is .25 micro farads not 25. I just measured one to make sure. Any non electrolytic type of capacitor will do (mylar etc). The problem with most capacitors is that they have solid leads that will break due to vibration.  

 

No amount of skill or education will ever replace dumb luck
1971 2002 (much modified rocket),  1987 635CSI (beauty),  

2000 323i,  1996 Silverado Pickup (very useful)

Too many cars.

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allbim, I'll double check the VR sensor gap with a feeler gauge, it may be a bit off since I haven't adjusted it since I installed it. Good call on the capacator being .25uf. That is the exact problem I am having, finding one that does not have solid leads. 

 

Do you have any pics of the capacitor mounted on your car?

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

A bunch of Bikes...

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chech the pins at the EDIS4 12 pin connector if you have excessive pin drag better known as loose pins or corrosion (that blue stuff) that  builds up it can be just as bad as a bad ground especially at the 2 pin connector for the crank sensor. when i first built my megajolt i had a ton of drivability issues then i cleaned and checked all the pins with electric contact cleaner. 

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I cleaned off the connectors for the coil pack and the edis using a small allen key to get inside the molex connectors and was able to pull them out a tad. It must have gotten everything to seat a little bit better because the misfire happens far less often now. I'm going to just settle and say this is as good as it is going to get with the sh*t wiring that is in there now. The replacement connector I have from millers mule has thicker gauge wires and is a lot stronger then what I have now. I checked the gap and it is on the tight side (about .2mm is what I felt, but hard to tell thanks to that magnet in there) so maybe that is causing some issues as well. 

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

A bunch of Bikes...

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also make sure to check if the trigger wheel is stright and true if you bought a kit from 02again.com then its probably not an issue but iv seen ones that people have jb welded and have a small amount of deflection witch can upset the crank sensor (they dont like it) if all that is ok then its time to start measuring voltage drops. this is why most shops dont want to deal with megajolt or megasquirt.

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also make sure to check if the trigger wheel is stright and true if you bought a kit from 02again.com then its probably not an issue but iv seen ones that people have jb welded and have a small amount of deflection witch can upset the crank sensor (they dont like it) if all that is ok then its time to start measuring voltage drops. this is why most shops dont want to deal with megajolt or megasquirt.

 

 

It's an 02again pulley... very pretty :). Definitely runs true. If I had a lathe handy I would have modified a pulley and shrink fit an edis wheel on, but I don't so I found a good deal on a trigger wheel. 

 

Voltage drops! What's the general idea... Measure voltage starting at the fuse box, then at each component? 

 

*does research* 

 

http://www.fluke.com/fluke/usen/community/fluke-news-plus/ArticleCategories/Electrical/DiagnoseVoltDrop.htm

 

 

Okay, I get the general idea. I'm guessing I need to measure voltage going to pin 8 on the edis and pin 2 on the coil pack... where else? come to think of it, I think the +12v wire feeding the edis also feeds the megajolt and the coil, and the wire is pretty thin. Might have worked at first but over time the resistance caused the wire to heat up and melt some of the insulation somehow causing a voltage drop? just speculating. 

1974 Grey European Market BMW 2002 

1976 Yellow BMW 2002 "GOLDENROD" SOLD

1972 Yellow Austin Mini 1000

A bunch of Bikes...

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