ViribusUnits

Well, my new ignition coil came in today. I installed it, adn I've got the same old problem. When I get to 4k rpms, I can go no faster. The ignition just cuts out.

Now I'm confused.

I'm trying to see if the wire between the various connecters in ther harnass are shorted together. Sometimes I think so, sometimes I don't.

The grounds are good. The coil, resisters, plugs, cap are new. The plug wires are in good shape. Only thing not new is the brain box.

As far as I can tell, everything is inside book spec.

Any other suggestions?

Thanks.

WallyP

What about movement of the distributor shaft that puts the pickup out of distance tolerance?

ViribusUnits

Well, wally, as far as I can tell, there wasn't any, but I'll go back tomarow, nad check it again.

The thing that bugs me is that I know the ignition basicly cuts out. The external tach that I have wired up to the coil drops alought, basicly telling me that it stops pulseing.

I can't figure out why, unless there's a bad brain.

Would a lose shaft in the distributer make it so the reluclator gets out of sink with the magnetic pick up?

Oh, btw, one something gets warmed up, it goes away for about an hours worth of driveing, and then it comes back. It's like a switch is switched on or off.

Thanks.

ViribusUnits

OK, latest news. I'm confused, please help.

Wally, there is no side to side play in the distributer shaft. There is a very small amount of play up and down. Maybe most of a mm.

The rotor and distributer are still good.

I just noticed something. I rather throught there was suppost to be some sort of plastic protector over the magentic pick up coil. I keep rembering a picutre with some sort of green shirnk wrap looking stuff. There isn't on my car. I thought that was a picture of a 928s distributer, but I can't rember.

The behavor of the miss is exactly as before. It acts as a rev. limiter, untill something warms up, and then it goes away for about and hour, some times more, some times less, and then it comes back, and doesn't go away. When the miss happens, it seems like the ignition is being cut out. The external tach. agrees with the internal one. The car's tach is of course hooked up to the tach feed, while the external tack is wires to the negetive side of the coil.

Question, is the ignition module suppost to make the dwell change as the car revs up? When the miss is not there, as the car revs up, the dwell seems to get longer, but when it's there, it doesn't seem to change nearly as much. I rember checking it when I went through the service mannual, and it was OK, but I don't rember reading if anything changes as the engine revs. up.

Thank you.

Old & New

VU,

I remember talking with you about this months ago.

Where do you stand on all the previous suggestions? If you summarize where you are at with all the old stuff, you might get some new ideas out of people. (Otherwise this will just turn into the thread that wouldn't die.)

If both tachs cut out, then it could be an electrical fault with the brain or pickup, yes. Swap brain or pickup yet?

Dennis Wilson

VU,

Are you still just getting 3 volts at the coil when it cuts off? If so, check/clean the O connector/plug on the fuse panel and the 30 and 15 posts on the starter solenoid. Also, check your battery and ignition module grounds.

Dennis

BC

I can understand your frustration. I had a cut out in the same way, but I put in a stock ign box, and it went away. I also replaced the Fuel injection relay.

reno928s

I had a problem like that one time but in a different vehicle (BMW). What happened was the car would cut out then drive normal then all of a sudden it would cut out again. That problem turned out to be a hairline crack on the mother board for the brain box. I would leave that for last and would try Brendan's way first. Sal

Lorenfb

The '83 928 should have a EZK box and not a
distributor pickup. If it does, then it has
an inductive discharge ignition unit on the
right fender upfront. This unit may have
developed a problem.

Please verify what type of system you have.

Good luck
Lorenfb@aol.com

ViribusUnits

Thanks.

I was afraid of that.

I know the 83 car, like all the pre LH-jetronic cars, doesn't realy have a "brain" controling the ignition. There is a box located by the passangers side of the car, in the engine bay near the radaitor. All it does it turn the ac single from the magnetic pick up, and relucator, into a square pulse of the proper duration for the coil. The advance is hanndled by a set of centrifical weights, and a a vacume advance. Since the advance and retard are not computed by the box, it's not a true brain, I think. An "inductive discharge ignition unit" sounds about like the right name for it.

I know I don't have the EZK brain box next to the fuel computer, in the passanger's foot well.

Looks like the ignition unit has a problem, that was the last thing to check. But since you can't check the unit with out swoping another one in, it's a rather expensive check. I'll get a diffrent one.

Thanks.

ViribusUnits

A list of everything I've done so far.

New plugs, distributer cap, coil, and ballast resisters.

The rotor, plug leads, and wires seem to be OK. They all ohm out as in specs, with no shorts that I can tell.

Both the frount right and left grounds have been cleaned. The engine to frame ground has been cleaned. The negetive battery terminal to ground has been cleaned. All of the connections in the ignition system have been cleaned, including but not limited to, the 6 pin connecter for the ignition unite, the 2 screws on the coil, the 4 connecters for the ballast resisters, the 8 pin connecter on the fuse/relay pannal, and the 15 pin connecter for the tach. Plus I'ce cleand all sorts of other connecters while going through it.

I've checked the voltage at the coil, both termianl 1, and 15. Termenal 1, the negetive side of the coil, has 1.80V when the key is on, engine off. Terminal 15 has 4.4V when the key is on, engine off. This is well with in book specs. The dwell at idle is, IIRC 32 degrees. At idle, the timeing light doesn't "skip" at all. It's a steady flash.

The advance works like it's suppost to. I pulled a vacuum on the advance unit, works fine, and hold vacuum. The centrifical advance also works. Checked with a timeing light.

When I'm driveing it and I run it in to the miss, both the internal, and external tach. indicate that the ignition is basicly cut out. If I hold down on the throtal, black smoke pops out of the exause, in addition to a backfire.

It seem lik I've gone throguh everything it could be, excepting the brain. Look like I'm out of luck. Any one intersted in buying a nearly new coil?

Thanks for the help.

Dennis Wilson

VU,

From looking at the troubleshooting chart in the manual, you have performed all the tests except checking for battery voltage at the 15 connector of the ignition module plug and the tach test. If there is battery voltage, try disconnecting the tach (12 pin connector under dash or connector G under the fuse panel). If disconnecting the tach doesn't fix the problem the module is probably bad. Is there anyone in the Houston area that has a similar 928 who will let you do a temporary swap? BTW all the ignition modules from 78 to 83 are listed as the same part number in the manual.

Dennis

ViribusUnits

I'm sorry, I forgot to include those tests.

I did the pull the plug on the tach test a long time ago. Did it again recently, didn't fix it.

I checked for porper voltage on the power cable to the ignition unit. I forgest exactly, but it was on the top side of 12 volts, so it's good too.

I'm not realy in Houston, and I'm not active in the PCA, currently to many other demands on my time. Plus I haven't realy put much effort in that diriction. I don't know anyone else with a 928, so looks like I'm trying to buy a used one.

IIRC, my study into this tell me the US 84 also had the same ignition unit, but the Euro 84 had the EUZ unit.

Well, at least now I know what the problem is.

Thank you.

reno928s

Viribus, I left the previous post with the brain box malfunction. Like I said my car, with the throttle down would backfire and shoot black smoke out of the tail pipe. If what you are saying that you don't actually have a brain box then I would look into whatever takes it's place. Sal

Lorenfb

Your problem is a difficult one to trouble-
shoot since it happens at a high RPM. You
really need a scope to check for the problem.

You might try and tap on module to see if it has
a bad internal connection. Also, clean the
main connector into the unit. This is usually
the major problem, as I think it points to the
front to take on water when driving.

Good luck
Lorenfb@aol.com