Spark on only one side of the Engine

[DeLoreanDMC81]

Hey everyone!

So I’ve got a strange problem going on. I’m only getting a spark on the passenger side of the engine, and absolutely nothing on the driver side.

I had the car running last April, my clutch line went out on me and the car sat for a while. I finally replaced the line and slave cylinder last Friday and was all ready to take the car for a much needed drive, around the block.

I went to start it and all it does is crank. The fuel pump runs, and I did all the normal bypass tricks with the jumper wire, nothing worked. I checked the ECU and the numbers were jumping all over. I checked the coil and it seemed to be reading good. But I’m only getting a tiny spark on the passenger side of the engine, and absolutely no spark on the drivers side of the engine.

I am absolutely stumped on what to do! I didn’t bump anything, or knock any wires off. The only wire that did come off was to the ballast resistor, but I hooked that one back up.

Any recommendations to help figure out the problem would be greatly accepted. I’ve been reading things and trying to look things over on the car for nearly a week and I’m slowly going insane.

I wish my Salt Lake City Delorean group was good at, oh, I don’t know, actually meeting up. I’d enlist their help, but that group never does anything. So I’m left to try and figure this out myself.

Thanks everyone!

James

[Bitsyncmaster]

There really is nothing electrical that can make it only fire on one side of the engine. Now with weak spark on the other side I would try bypassing the resistor (or even bypass both) and see if it starts. You may have a bad connection (crimp) on that wire you bumped off.

[Ron]

+1

If it's a stock set up and nothing involving the ignition has been changed since it ran, it has to be related to the cap. Possibly moisture inside it cap...

Put a plug wire on the coil and see if it sparks to ground normally while cranking the engine over.
(Compare with another car if you don't know what to expect...)

[DeLoreanDMC81]

Alrighty, how do you go about bypassing the resistor?

As for the vehicle, everything on the car is 100% stock, except for the master cylinder, clutch line and slave cylinder.

This whole thing is just super frustrating because I’m just not sure where to go, at this point?

It will eventually be figured out, just gotta stay at it.

Thanks,

James

[David T]

Don't try to "bypass" the ignition resistor. Just try cleaning the contacts and see if that improves the spark. If the battery is weak you would also get a weak spark or no spark. Make sure the battery is fully charged. If that doesn't do it you probably need a tune-up which includes replacing the cap, rotor and spark plugs.

[FABombjoy]

Spark on one half is possible if the distributor cap were (somehow) rotated, or the alignment between the pickup & rotor were changed.

Also might be possible if the distributor pickup wires are reversed. This inverts the VR signal and IIRC the ignition ECU uses zero crossing detection for trigger. With the wires flipped the AC signal is 180 deg out of phase AND will trigger like an even fire motor due to the pole piece design. The ignition ECU would detect the pole piece in the wrong spot and trigger spark at the wrong time. The existing weak spark could be due to rotor phasing if the pickup->ECU->rotor timing is off.

How likely is any of this? Who knows, but it's all quite possible and only further exacerbated by an odd-fire distributor.

[Parzival]

I had an issue like this after taking the intake apart and doing a bunch of messing about in the engine. I would get spark inconsistently, but if all I did was check spark at one or two plugs it looked like it was working (this is what I did, so I ended up investigating in the wrong places and wasted a lot of time) In fact I never found it because I thought spark was fine, Robert at DMC FL ended up coming out and finding the issue. I live to learn another day I guess, lol.
Anyway it turned out the rotor was not pressed down all the way under the cap. It was not turning and making properly timed connection, or connection at all on some cylinders.
So with your issue something must be up with the rotor or cap to cause this I think. The spark is being generated its just not getting to all the right places. So unless you have loose spark-plug wires on 1-3 or 4-6 I'd look there.