NON ZR-1 Technical Help needed

[limey]

You guys are smart and i know we have some ECU geniuses here, so i pose my dilemma.

I'm been trying to convert a lamborghini that uses Marelli 3 pin C.O.P. ignition coils to the more common and easy available VW AUDI 4 Pin coils.

For the love of me, i can't get a spark. I switch back to the 3 pin coil and fires right up.

Ive attached 2 pdf pages, the 2002 Murcielago uses Marelli 3 pin, the 2004 uses VW 4 pin coils.

On the 2002 cars, the coil wiring is as follows:

Pin 1 = 12V Power
Pin 2 = Signal Ground
Pin 3 = ECU Signal

On the 2004 cars, the coil wiring is as follows:

Pin 1 = 12V Power
Pin 2 = Signal Ground
Pin 3 = ECU Signal
Pin 4 = Chassis Ground.

So, why when i ground pin 4 on the 2002 retrofit, the car doesn't fire?

[GOLDCYLON]

What happens when you Ground 2 and 4 together or are you running pin 4 to a seperate ground?

[XfireZ51]

Which ECM are you using? And has this retro been done before?

[XfireZ51]

I have a feeling the 4 pin Chassis ground is short circuiting the Signal w the VW coils. Are these coils of equal output?

[limey]

What happens when you Ground 2 and 4 together or are you running pin 4 to a seperate ground?

Nothing, same no spark issue

[limey]

I have a feeling the 4 pin Chassis ground is short circuiting the Signal w the VW coils. Are these coils of equal output?

The VW coils read a LOT higher resistance than the stock ones. I was told that i may need an ignition amplifier, but haven't looked into this yet.

[Paul Workman]

Well, right off the bat, the schematic for the Lambo coils leaves a lot of questions. That and exactly what/how the (ECM) signals the coils: beit a ground or??

And, another thing: If I signal trace the VW circuit and go by the schematics provided, either the schematic for one or the other is wrong, or it is a positive ground whereas the Lambo is a negative ground chassis. Do we know that to be the case? Cuz if it is, it makes a big difference how the switching transistor is biased on, and explains why the VW coil will require some faniggling to make it work.

Note: RE the 4 pin coil: The collector of the transistor switch is grounded, and appears to be a NPN (if the diagram is correct). The emitter connects to (I presume) the battery, and to bias the transistor ON, the emitter voltage would have to be to be negative in relation to collector. That would suggest the chassis is a positive ground, assuming the schematic symbology is accurate. Or, am I missing something?

It may be possible to fanigle the VW coils, but to see what is what, a breakout of the Lambo coil is required; that or taking a whack at guessing how it is configured and experimenting. Do you have one of each in hand? (I'm guessing you do.)

[XfireZ51]

I'm thinking the VW coils are much more powerful than the 2002 coils and so have discrete power and ground. The 2002 ECM likely can't handle them.
BTW, I have read that the VW guys swap in LS-2 coils due to reliability issues better dwell time properties. And of course the LSx coils are 4 wire.

[scottfab]

Very interesting indeed. I've noticed two design elements obfuscated into the schematic which explain why shorting 2 to 4 on the four wire design does not work.
Since this is not a ZR-1 issue for a donation to the club I would consult on the what's going on. Certainly the cost could be passed on to the owner of such a fine automobile.

[geezer]

Kurt; Hope you find a solution for this. BTW still waiting for your parts to arrive here. Check your emails.
Thanks; Bill

[limey]

Very interesting indeed. I've noticed two design elements obfuscated into the schematic which explain why shorting 2 to 4 on the four wire design does not work.
Since this is not a ZR-1 issue for a donation to the club I would consult on the what's going on. Certainly the cost could be passed on to the owner of such a fine automobile.

I have no problem with this at all, I'll donate $500.00 to the club if what you tell me works and show us how to implement it. I've spent countless hours and resources on this, so money well spent. Mind you, if your solution doesn't work, no money donation, sound fare?

Bill, will get with you on this tomorrow, will need to look into this.

[scottfab]

I have no problem with this at all, I'll donate $500.00 to the club if what you tell me works and show us how to implement it. I've spent countless hours and resources on this, so money well spent. Mind you, if your solution doesn't work, no money donation, sound fare?

Bill, will get with you on this tomorrow, will need to look into this.

Kurt, Good enough, does Bill have an email address?
I can walk him through a bench test then wiring changes.

[limey]

Scott,

Can you pm, or call me with the info. Once confirmed that this is successful, I will paypal $500.00 to the registry.

Kurt.

[scottfab]

Kurt, I will call later on today but be aware. The bench test (or putting the coils into another car) will be needed first to verify component viability. If they were wired wrong initially the internal transistor could have been fried.

From there a few "on car" measurements will be needed the a "where to cut" process. Does the car run at all with the old coils? If so that speeds up the mod.

[limey]

Car is in house and all tests can be confirmed. I have lots of coils :-)

[scottfab]

OK Kurt, Here is what I've found.
To start with the pdf schematics for the 2002 and 2004 are more of a logical diagrams and do not contain all actual specifics of the circuit.

Having said that and after examining both coils I now know enough to say the 2004 circuit uses a positive transition pulse to turn the coil (create HV at the output).
The 2002 circuit uses a negative going pulse to do the same.
An example here shows what the two look like. First is the 2004 pulse
the second is the 2002 pulse.
http://1.bp.blogspot.com/-_RhrcMIcwQY/T4ymHrGV-vI/AAAAAAAACqg/61meXkrwjpk/s1600/Screen+Shot+2012-04-16+at+7.07.02+PM.png (http://1.bp.blogspot.com/-_RhrcMIcwQY/T4ymHrGV-vI/AAAAAAAACqg/61meXkrwjpk/s1600/Screen+Shot+2012-04-16+at+7.07.02+PM.png)

What does this all mean? It means just changing the wires in the harness and shorting pin 2 to pin 4 will not work.
What has to happen is an inversion of the pulse on each coil input from the ECM.
This can be done by adding a transistor (and possibly other protective components) to each coil. I can furnish a rough schematic of this.
Sorry I know this is not what you were hoping.

BTW the output voltage of the 2004 coil is MUCH greater than the 2002 coils.

[XfireZ51]

Scott,

I think what you have discovered is very similar to what we did in adapting the LSx coils on the LT-5. In our case, we converted what was grounding the coil by the Ignition Module into a triggering signal. The signal was ~.4v and it was inverted.


OK Kurt, Here is what I've found.
To start with the pdf schematics for the 2002 and 2004 are more of a logical diagrams and do not contain all actual specifics of the circuit.

Having said that and after examining both coils I now know enough to say the 2004 circuit uses a positive transition pulse to turn the coil (create HV at the output).
The 2002 circuit uses a negative going pulse to do the same.
An example here shows what the two look like. First is the 2004 pulse
the second is the 2002 pulse.
http://1.bp.blogspot.com/-_RhrcMIcwQY/T4ymHrGV-vI/AAAAAAAACqg/61meXkrwjpk/s1600/Screen+Shot+2012-04-16+at+7.07.02+PM.png (http://1.bp.blogspot.com/-_RhrcMIcwQY/T4ymHrGV-vI/AAAAAAAACqg/61meXkrwjpk/s1600/Screen+Shot+2012-04-16+at+7.07.02+PM.png)

What does this all mean? It means just changing the wires in the harness and shorting pin 2 to pin 4 will not work.
What has to happen is an inversion of the pulse on each coil input from the ECM.
This can be done by adding a transistor (and possibly other protective components) to each coil. I can furnish a rough schematic of this.
Sorry I know this is not what you were hoping.

BTW the output voltage of the 2004 coil is MUCH greater than the 2002 coils.

[XfireZ51]

Oh 1 other point. The LSx coils required a 20A power circuit for each side.
Ran that direct from battery w relays for switching ON. Think I still have the harness for that.

[scottfab]

Oh 1 other point. The LSx coils required a 20A power circuit for each side.
Ran that direct from battery w relays for switching ON. Think I still have the harness for that.

That must look pretty interesting. I think in this case it should be possible to invert the signal directly and to do it with as few noticeable appendages as possible. There are 12 coils and the wiring is already set up for individual coil driving. The current load is easily handled by the existing wire size. The fuse may need to get bigger.
We'll see.

[XfireZ51]

The wiring is the in the LT-5 also but it uses a 10A circuit for the coils.
As you have already noted the VW coils are much more powerful than the 2002 coils. That takes more power. Is the 2002 circuit up to it?

[scottfab]

The current load is easily handled by the existing wire size. The fuse may need to get bigger. Don't know what it currently is.

Using an old power transistor I had laying around I just proved inverting the ECM signal will work. The current draw is <5amp on each coil. Since at no time does any more than one coil of the 12 fire at the same time that puts the total current needs at <5amp for the wiring. Fuses tend to be put at 200% of actual circuit draw so that means a 10 amp fuse would be fine.
At least those are the readings so far using a test bench power supply. Next would be using a 12V battery which has lower internal resistance than my bench power supply.

[XfireZ51]

Scott,

What do you think would happen to current draw if you consider overlapping dwell of coils?

[scottfab]

Scott,

What do you think would happen to current draw if you consider overlapping dwell of coils?

The important thing seems to me is the initial draw of the coil (T zero) and that can only happen to one coil at a time.
That "real" current will be soon measured on the new "hot" coil. I have some proto-typing to do before that. I'll know in a few hours. With that number a determination of overall current demands could be estimated. At idle I don't think dwell will overlap. At what rpm they do overlap is not part of my current task. I consider that to be less challenging and solvable with several solutions.

[scottfab]

The measured current for one of twelve coils is a peak of 7amps
on a bench setup.

Kurt reported this morning that the converted coil (again 1 of 12) sparks in the car when driven by the ECM. Converting all 12 would be the next step. :cheers:

[XfireZ51]

The measured current for one of twelve coils is a peak of 7amps
on a bench setup.

Kurt reported this morning that the converted coil (again 1 of 12) sparks in the car when driven by the ECM. Converting all 12 would be the next step. :cheers:

Scott,

So are you converting the 4 wire to three? As I read it, you've inverted the current ECM signal so as to trigger the 4 wire coil. What have you done about the 4th wire?

[limey]

I'm most pleased to advise, Scott Fabre is the man!

Put in the car today, sorted out the initial glitch and got the car running on all 12 cylinders again.

This time, 11 cyls with the old 3 pin Marelli coil, the 12th with the VW Audi 4 pin plug.

Thank you!

As promised, who do i send the donation to?

[scottfab]

I'm most pleased to advise, Scott Fabre is the man!

Put in the car today, sorted out the initial glitch and got the car running on all 12 cylinders again.

This time, 11 cyls with the old 3 pin Marelli coil, the 12th with the VW Audi 4 pin plug.

Thank you!

As promised, who do i send the donation to?

Please stand-by

[GOLDCYLON]

WTG Scott

[limey]

As agreed, i've paid my $500.00

Thanks for the job well done.

[XfireZ51]

As agreed, i've paid my $500.00

Thanks for the job well done.


So can we see this beast running w the VW coils installed?

[limey]

Sure you can, once i get the harness made, right now it's a rigged up harness and only one coil firing on the 4 pin VW.

[scottfab]

Based on numerous circuit simulations I predict NO dwell issue what so ever. The Ferrari wire harness is MUCH more stout than the ZR-1 and can most easily handle the current. And I suspect the fuse adjustment, if needed, will be trivial.

[XfireZ51]

Excited to see what you have done here.

[GOLDCYLON]

Excited to see what you have done here.


Maybe Scott could re-breath life into your LSX coil project Dom?

[XfireZ51]

Maybe Scott could re-breath life into your LSX coil project Dom?

Any help would be great. I'd be happy to share what we observed when we tried this a few years ago now. =D&gt;

[scottfab]

Any help would be great. I'd be happy to share what we observed when we tried this a few years ago now. =D>

Not familiar with that thread. Maybe I can be pointed at it and/or a new thread started?

[GOLDCYLON]

Not familiar with that thread. Maybe I can be pointed at it and/or a new thread started?


Here you go Scott

http://www.zr1.net/forum/showthread.php?t=8053&highlight=coil+project