ViribusUnits

If most of ya'll with think back, I've had a rev. limiting ignition problem since I bought my car last october.

I can rev the car up fine, under load or not, to right below 4,000 rpm. There, the ignition basicly cuts out, and she won't go any higher. The tack falls to 0. If I hold it there, a simply huge amount of fuel gets dumped into the exaust, and black smoke apperes. Yuck.

I've gone through everything in the system. The coil, magnetic pick up, resisters, and such all Ohm out OK. I've clean the right and left grounds on the frount corss member. I've claned the plugs on the fuse/relay pannal. I've also cleaned the resister, coil, green wire, and brain plugs/screws. They are so clean, they now reflect my frustrated face back at me.

In frustration, and in an attempt to double check my tack, I ran a wire from the coil to the inside of my car. There I wired it to an external tach/volt/dwell meter. The tack was right. When I get just to below 4,000 rpm, the external tack loses about 1,000 rpm. The dwell is constant, even when the igniton basicly cuts out. The realy intersting thing is that when the voltage on the coil drops under 3V, I have the rev. limiting miss problem.

Sometimes it's like that. Sometimes however, it's like a switch is fliped, and the voltage never hits the asymtopic line at 4,000. Instead it stays between 5 and 7.5. Under that condition, there is no rev. limit, and I go all the way to 6,000 np. Since I've been messing with the thing, the rev. limit's charator has changed. Use to be, it was like that all the time, no matter what. Now it misses when I figure start up for have 5 minuts. Then the rev. limiting miss is gone for about the next hour and a half. After that, the miss returns, exactly as before. If I slow down and idle for a while, the miss goes away for a few minutes. Several times, the miss has returned while I was above 4,000 rpm. It was like a switch was fliped, and the ignition was cut out till I got below 4,000 rpm, and then it was as before.

Does this sound like a brain problem? I've checked and rechecked everything I can think of, and now I'm going nuts. I realy don't want to buy a new ignition module unless I have to. I can't think of what else it might be.

Thank you.

Barry Johnson

Have you replaced the coils? I've heard that while they may ohm out ok, they will still do exactly what you're experiencing. I'd go ahead and do that.

Normy

Something's overheating~

Good luck-

N!

Dennis Wilson

When the voltage drops to under 5 volts at the coil is the voltage from the starter to the .4 ohm resistor a constant 12 volts? If not you have a bad connection or wire from the 16 or 30 post on the starter solenoid. If it stays a constant 12 volts the resistor(s)are bad and building more resistance when warm.

Dennis

Erik - Denmark

Viribus,
Only a thought - Can it be the revolution limiter?
I am not familiar with the 83 US model, but you can check it yourself.

Dennis Wilson

Erik,

On the 83 the ignition module gets its power through the .4 ohm resistor. Also, I believe he has tried jumpering the fuel pump relay, which would rule out the rev limiter.

Dennis

ViribusUnits

It's deffently something in the ignition. the rev. limiter cuts the fuel pump, no dice. Also, I jumpered the fuel pump, no effect.

As of yet, I've yet to test the resisters, or the other side of the coil. If I can find some place upstream of the negetive side of the coil, with the correct voltage, then I should have it, right?

I'm thinking about wireing the two leads of the volt meter to the two sides of the primary coil. If there is ever much of a voltage diffrencial accrost the coil, I should have my problem, right?

Thanks!

Dennis Wilson

The .4 ohm resistor has 2 black/yellow wires going in and one black wire going out. One black/yellow goes to the starter and one goes to the other .6 ohm resistor. The black wire goes to the ignition control module.

The black and yellow wire that runs from the 16 post on the starter to the .4 ohm resistor would be another possible offender.

Check the connections (3) at the starter solenoid and while you are down there, check the ground from the body to block.

Do you have the factory schematics? If not send an e mail and I'll scan it for you.

Dennis

ViribusUnits

Dennis, I already been there, done that.

The .6 resister was looking bad so I replaced it. When I go back now and check on it, it reads out OK, just looks bad, and has a crack.

The connections are shiney now. Both the grounds, the resisters, the coil, pretty much everthing.

I've got the factory schematics.

This is why I'm frustrated. Everything Ohms out good, the connections are good, and yet, I've got a problem.

I'll see if a new coil helps. If not, well, I'll go from there.

Dennis Wilson

Even a new coil will not fire with your measured 3 volts. Are you sure the cracked resistor isn't making contact when cold but dropping off when it warms up? Try putting jumpers across the two sides of the relay and see if the problem goes away. BTW don't run it too long jumpered as the coil wasn't designed for 12 volts except at start up.

Dennis

Bill 86.5 928s

Hey Viribus: Check out pages 28/11 to 28/19 of the engine manual. Ignition troubleshooting...you should have 3 volts at term 15 with ignition switch on, engine not running...Good luck

ViribusUnits

I'm quite sure the cracked resister isn't causeing the problem. It's been replaced. It was only after I had already replaced it that I Ohmed it, and it checked out OK.

Hay bill, I already been there, done that.

Both termanel 1 and 15 check out OK.

Over 3V at terminal one, and about 1.8V at termanal 15, very nicely between 1V and 2V. Exacly as per book spec. before I start her up.

I think I just found my problem though. I wired up at volt meter between termanal 1 and 15. Engine one, below the miss rpm, voltage diffrence of about 1.30. Engine on, and misisng voltage diffrence of about 2.5+ Engine on, above the 4k limit, with out the miss, and the voltage diffrence about 1.30 The voltage before the coil is stable, when compared to the frame ground.

I belive I just possitively identifyed a bad coil. hum... How much is a new coil...