Lizard928

I figured I would post this on here and try to get some of the other great minds on it as I am sure that Louis has had just about enough of me pestering him
Thanks again BTW.

Ok the brain is MS II V 3.57

I am running them wasted spark arrangement.

I am generating with the MS +5V logic signal to the COP units.
Pin #1 ECU ground (all soldered together with a single lead attaching to chassis)
Pin #2 engine ground
Pin #3 +12V constant.
Pin #4 +5V signal/trigger.

I have verified with an oscilliscope (bought one today). That I am getting a proper square wave +5V signal from the MS to the COP units.

At first I was having a problem with the dwell being too high while cranking. I was however able to correct that problem and have now tried cranking with 2, 1.8, 1.5, 1, and 0.7ms dwell times on the +5V signal line. The coils will still not fire.

I have taken the coils and put manual pigtails on them and held the plug, pin #1, and #2 to negative, and held pin #3 to positive while dragging/arcing #4 to the positive. This produces a nice thick spark verifying that the unit is indeed functioning.

Now I have gotten the Cayenne COP units to work on another 928GT but we were using VEMS. We also had trouble getting them to fire on that car. What we ended up doing was using a different section of the board (stepper IAC) circuit to drive the coils. But the stepper IAC uses 12V instead of +5V. I cannot recall if the reason we did that on the VEMS was because the signal was actually -5V or if there was another problem.

So if anyone has any light that they may care to shed on this situation. Or any possible things to try I would be MORE than keen to try.

BC

These coils have had such close scrutiny by Todd, Louie, myself, and a few others that I don't know why there is these problems. When Todd had them tested by AEM (you can send in coils I guess) they said a few things about them - and the jist is that they are sensitive. Sensitive to voltage irregularities, as well as the falling edge signal - but this was in the sense that the falling edge - if not clean, can cause multiple sparks.

You, however, are getting no spark.

The dwell needs to be quite low as I recall on these.

When the falling edge starts - does it go low cleanly?

BC

It has to be something with the way MS is dropping the 5V off. My emotive response to this, from all my info, (simply intuition) - is that the 5V needs to be dropped off a cliff, and cleanly, and these things will work up to, as Louie said to me in 2007 "F1 speeds"

Lizard928

Louis ran many tests on the COP units and stated that in his memory if he went about 2.0mS dwell time that they just shut off or went really funky.

The other car that I have running these is running 1.5mS dwell time and has no issues with that dwell time.

The falling and rising edge are as far as I can tell on the oscilliscope not even there. IE it is like a rock falling off a cliff. Very clean. It is a very neat square wave signal. So 0V, +5V, 0V.

This is what is kind of confusing. I am tempted to try to convert the +5V signal to a +12V signal and see if that triggers them. As that is what ended up happening with the other car.

Lizard928

This should give you an idea of the signal. Dwell was too long in that video. But will give you the idea of the signal. Time is 1mS/CM

http://www.youtube.com/watch?v=IZlssoUuA-I

PorKen

Does the engine have good ground?

Lizard928

Hey Ken,

The engine has a perfect ground and I have verified voltage and signal between the engine ground, and ECU ground. I have also measured voltage from basically the jump post to the engine ground and ECU ground and there is not even .01V difference between them.

Keep the thoughts coming guys

Mike Simard

I sent one of those to Motec for testing. They found that the coils will shut down at exactly 20ms. They would resume firing as soon as it dwell got below that.
That prevented me from using them because of the Motec pesky cranking dwell but otherwise Motec seemed to be impressed with them.

The 5v+ trigger signal is something I don't understand. I thought it should be a 'ground' signal but I don't understand that terminology well.

I bet Alan would be able to shed some light.

Lizard928

Hey Mike,

I am glad you are able to chime in here. Are you sure that it was 20mS?

I had thought from previous discussions that it was 2.0mS not 20mS.

And I can say from experiance that they do fire with a positive trigger, and definetly dont with a negative.

Do you happen to have an email from them that you could confirm that in?

Mike Simard

Yes, it's twenty milliseconds for the shutdown.
That is a huge amount of dwell and shouldn't be a concern for anyone not using a Motec IEX. It's just that the IEX has that silly long dwell time during cranking and that can't be changed with settings, it's a hardware thing.

Lizard928

Thank you for the confirmation Mike,

I got another email from Louis, it seems we triggered something in his brain and he has found that the coils need a minimum of 18ma in the signal. And this is more important than the amount of voltage.

I will be speaking with the people at MS tomorrow to find out how we can modify the signal to get that into the signal.

Tony

cool stuff!

Lizard928

After talking to the guys at MS, I will jumper a 100 ohm resistor from the 5Vref line (for TPS) to each of the 4 logic level ign drivers and this should supply the needed amps to drive the COP units.

I will post an update stating if it works or not.

BC

So the theory currently is that the MS does not have enough amps out of the logic level ign outputs to run the coils?

User 4221

Are these new coils? What version .03 or .05?

I ask because they are notorious for cracking and failing. They may fire intermittently but beware that they are not the most robust units mechanically.

A quick search on the Cayenne forum will give you plenty of info on failures. BTW, I've had mine replaced twice.