Sudden sync loss

[S_Mitchell]

I've been running spark only for the last 5 years with no issues. Last week my engine started running rough and wouldn't crank after it died. I put the stock distributor back on it to get home and run some diagnostics. For some reason I'm not getting much signal from my VR sensor below 1000 RPM, so the coils will not fire to start the car. Also I get a sync loss around 3000RPM, but it is fine above that and below it to 1000. I haven't fooled with this thing in 5 years because it ran so good, now I'm like a noob again.

My set up is MS1V3 direct firing a wasted spark coil pack. A few weeks ago I somehow cut a spark plug wire and ran a while before I figured it out (happened immediately after getting fuel and thought it was a fuel problem). It may be coincidence or could have damaged something from arcing on the engine?

[ps2375]

My guess would be electrical noise. Same plugs? Different wires?

[Clonebug]

Check your gap.....has your engine crankshaft endplay changed maybe????

[S_Mitchell]

Spark plug wire fits the time frame of when it all happened. The stock system would be very noisy to watch on the composit tooth logger. I'll try this first. Gap is .7mm pulley set up is like this https://goo.gl/images/aGj3e5 with a bracket holding the sensor over the top. It's thick and bolted to the fuel pump studs.

[S_Mitchell]

No luck today changing wires, plugs are the same I've always had. Tomorrow I'll pull the whole thing out and connect the stim.

[S_Mitchell]

I was fooling around with it this morning with TS attached. It's been so long that I don't even remember what the three LED's on the MS box mean. As I was trying to remember, I pulled some wires out of the way too get a better look and the relays went crazy. I kept jiggling wires and it would run fine, jiggle some more and lose sync. I tracked it to one of the VR sensor wires had come loose in the relay box, I don't know how it was running at all.

[ps2375]

Glad that it turned out to be a simple fix.

[Clonebug]

It really is amazing on how bullet proof these systems are.

That is the only complaint I have about the relay box is that the terminal strip will work wires loose if they aren't checked occasionally.

Fortunately I check my Buggy over and do lots of wiring changes so I check them at least 4 times a year.

Add that to your yearly maintenance program........

[S_Mitchell]

IAT was also loose and I've found that one out before. Didn't give it much thought at the time because I only use it for spark right now.

Will define checking them every winter now.

[ps2375]

For the years I ran MS on my Rabbit, I never had loose connection problems, but I never ran the b&g relay board.

[Clonebug]

For the years I ran MS on my Rabbit, I never had loose connection problems, but I never ran the b&g relay board.

The relay board has small screws and it's not easy to get a lot of torque on them.

I solder the wire ends to keep them from getting crushed so that could be a part of them working loose over time........or me forgetting to tighten them when installing.......