byrdman454

Swapped both amps with a known good set from the '84 Euro. No change. Still running rough.

byrdman454

Do both coils have a ground or just the drivers side?

ammonman

Both coils have grounds. Did you check both ends of the coil wires for corrosion? How about the smaller wires to each coil?

Mike

ammonman

Here's the resistance specs for the primary and secondary windings in the ignition coils.


Mike

byrdman454

The coil ground on the drivers side is broken, but I do not see any ground on the passenger side coil. Do both coil brackets have them?

I checked every spark plug for spark while cranking and they did. All plugs are getting some spark, not sure if it is enough.

How do I check the coil wires for voltage? Will they show power at all times or only during cranking? Just unplug from the distributor cap and check the voltage?

byrdman454

ammonmann, where do I check the resistance for the coils? Are the terminals on the ignition computer harness inside the car? If so, does anyone have a pin chart for that connector so I know where pins 1, 4 and 15?

byrdman454

I pulled the wire that connects the coil to the distributor. The ends showed no sign of corrosion. I did not check any small wires.

SQLGuy

Did you pull plugs when checking spark, or use an extra plug?

If you pulled plugs, how did they look? If you didn't pull them, you might want to to see if one is bridged or if there are some that look richer or leaner than the others.

WICruiser

There should be ground wires from the coil brackets to the engine on both sides if I recall correctly. It sounds like you only had one and it is broken. Coils may be firing weakly giving you an indication of spark but not the intensity that you need to get good combustion.

byrdman454

Pulled all the plugs when I checked for spark. There were some that looked like they were wet with fuel, others looked just fine. There was one in particular that was sooted up pretty bad, all black. I checked it for spark before cleaning it and it was still firing.

Podguy

First thing I would do is get in front of the cat and see how much raw fuel you are dumping. There are two tubes at the back of the heads to make measurements ahead of the cat. If they are balanced and and the HC is low then the fuel is not your problem.

I guess you have already removed the plug on the amplifier one at a time. If you remove one and the engine starts to die then that side is running. If you notice no difference then that side of the engine is not getting spark. If both sides are affected then the ignition is working correctly.

Right there you have eliminated a big part of the potential problems.

The next question is what did you do to the car before it started to run poorly. If you put in Ken chips did you change the regulator.

Then there is putting on a pressure gauge on the rail and checking your pressure. Does it hold pressure after you shut it off.

Finally try you computer in another good running car. The S3 computers are stable but they like anything else fail. There also could be wiring issues. There is a continuity test in the manual.

One other place to check is the timing belt. check the tension and timing. It is possible to run the car with it one tooth off.

ammonman

Terminals 1,4,and 15 refer to the terminals on each coil. Terminal 4 is the large wire from each coil to it's distributor. Terminal 15 on each coil has two black wires (+12V from the 15 buss in the CEL) while terminal 1 on each coil has a single brown wire with w black stripe (if I'm remembering my German color abbreviations correctly.) If the resistance readings are not within spec you have a bad ignition coil.

Mike

byrdman454

I removed the coils from the fender wall mounts and checked resistance.

Between terminals 1 and 15, both coils showed 1.5 ohms, so twice the upper limit per the WSM.
Between terminals 1 and 4, I am not getting any resistance values on both coils.

If I turn the key one and recheck 1/15, the value is a -3.2 ohms on both coils.

I doubt both coils would be defective at the same time and run. Am I running the test incorrectly? Does it have to be mounted to the fender bracket? I removed them to get better access to the terminals.

ammonman

The coils need to be completely disconnected from the cars wiring to do the test correctly.

Mike

byrdman454

Pulled the cam covers. No cracks or any damage seen on the rotors or distributor caps. Checked cam timing and it is spot on. Belt and tension appear to be fine.