greg1990964

My car has new coils now. With the old coils it would run if I took off one coil wire from the distributor cap, but car lost some power when hot, and had intermitten stalling, so changed them. Been great so far. No power loss, no cutting out anymore. So..Out of curiosity, I just tried it taking off one coil wire from dist cap with new coils and it died. Did it with both dist coil wires. I tried unpluging the ignition modules below the coil, and it stayed running on either. What gives here? Isnt that the same basic thing?
My question is, is the car supposed to stay running if you disconnect a coil wire? Why then would it stay running when a ignition module is disconnected? Maybe I am missing something here in my pea brain..

Shamus964

Disconnecting the high voltage line from the dizzy cap is very dangerous to both you and the electronics of the car should the voltage go into something not designed for it.

Not sure why it would die though - seems like it should continue to run.

greg1990964

Yeah, I know it is not smart. Not got a zap yet. But still weird that it will NOT run when you pull a coil wire off but will stay running with a ignition module unplugged. Hoping someone has the answer cause it has me thinking that my coil replacement did not do the whole trick.

Earlydays

Here is a possible scenario:
If your distributor belt is broken and you disconnect the coil from the primary distributor, the engine will stop, but if you are actually disconnecting the ignition module from the secondary distributor, not the primary, the engine will still run.....

greg1990964

Good point, but both dist spin. Saw it when doing the valve adjustment today. And disconnected the ignition module from both. Oh well. It runs great so I guess I should stop being obsessive about it. Thanks for the reply

mike9186

How old are your coil and plug wires?

greg1990964

I am not sure how old. Would old coil wires make a difference? Trying to work this out in my head..

mike9186

I don't have a specific answer for you but I recently changed out my plug and coil wires and it eliminated some electrical gremlins. I was having the Xmas tree effect on the dashboard when I turned on my headlights. I replaced the plug wires and was still getting the effect. Then I replaced my coil wires and the Xmas tree is now gone.

This is pure conjecture but, you may have a coil wire with worn out insulation and you are getting a short when you pull it off the center distributor post.

Good luck and keep us posted.

dutchcrunch

unlike the 993 which have 2 independent trigger for each coil the 964 has only one. maybe the high current has no where to go and your getting some kind of feed back screwing the ignition circuit up. this is not the proper way to test the ignition system, especially if the high tension lead is not placed near a ground . always disconnect the modules.

greg1990964

I see your point, but I used to be able to take off a coil wire from dist and car would stay running before new coils..I don't know, I guess I am overthinking it. The car runs great, and doesnt cut out once in a while anymore since i changed coils Guess I am wondering if I am not getting all the power I could.

greg1990964

Ok, I went for long drive and noticed getting on the highway when giving it the goose, it was a little sluggish. When I stopped I just pushed down on dist coil wires, and made sure ignition plugs were firmly in place and it all seemd fine. When I left rest area and the car had the old growl back and could really feel the pull through the rpms and such. I am now home and checked all this stuff again.

1:Car starts with either ignition module unplugged.

2: Car also stays running with either ignition module unplgged while running.

3 Car will die if I unplug either coil wire at the dizzy cap.

4: Car will not start if one coil wire is unplugged from dizzy cap.

I am at a loss here. Can't figure this out. Both distributers are working, and belt is fine. Maybe since it runs better after toucjing the wires, or modules, it is just coil wires? I can't see where you can just buy new coil wires. The plug wires appear to be in good shape, and not really in th ebudget to just throw $500 at new complete beru wire set. Plus I have done enough throwing parts at problems. Well, the coils and ignition modules are new, and the caps and rotors are only a few months old..Any ideas? Throw any crazy ideas out here..Please!

Rocket Rob

Greg - I can't think of a logical reason for this but I would suggest checking your distributor caps and rotors. There have been some recent threads about problems with Beru caps where the wires come loose. You may want to confirm this is not a factor.

greg1990964

The Beru caps I used to have had an electrode come right out of it, and just had an electrode come out of my Bosch cap now. I glued it back in and I think should be ok..I am ordering new ones after I try and get it replaced for free. Rob, let me think about the pm you sent me. Thanks.

Lorenfb

"Disconnecting the high voltage line from the dizzy cap is very dangerous to both you and the electronics of the car should the voltage go into something not designed for it."

As mentioned previously, that's basically it. In particular, the 964 DME ECM
is extremely sensitive to electrical 'noise', i.e. a HV spark, entering the sensor
inputs. This will most likely cause the ECM to generate a CEL, cause the engine
to mis-fire, or cause the engine to die.

This is why even when everything is properly connected that all the components
of the secondary spark signal (HV side of the coil) be in good condition, i.e. coils,
spark plugs, spark plug wires, rotors, and caps.

Bottom line: Don't ever run the engine with any of the secondary spark components
disconnected!

greg1990964

I understand the dangers of disconnection stuff. I am just confused why it runs with ignition modules unplugged but not when a coil wire is unplugged from dizzy. It used to run on old coils when wire was disconnected from dizzy cap. Is it supposed to run with a actual cool wire unplugged from dizzy? Or was it just odd that it use to run like that?