coil on plug conversion

[stoker100]

well im about 90% through the design stage of my coil on plug conversion for the probe and was wondering if anyone else out there has ever converted (or know of someone who has) a single coil channel ECU to run COP's (without changing the ECU), this means there are several problems to overcome (dividing firing outputs, finding cyl #1 etc).

ive searched and searched on the net and cannot find any information on it, i have heard of a few people doing it (obviously not to probes) but nobody has posted any information (schematics).

basically my process involves splitting the ECU output to 6 channels and driving each coil from MSD (at this point), everything i have built works on its own but is untested as a complete unit.

does anyone know where a good forum would be for this kind of stuff?

[shaodome]

check out http://www.diy-efi.org some cool stuff there.

You don't need to get 6 MSDs as that can get spendy. VB921s, IGBTs (make sure u have dwell control) or even 6 HEIs would suffice and save you 90% of the cost.

[ASword]

Actually I've been planning to do the same thing. PM me and we'll talk about my plan.

[Xplode]

ASword - I see you're in burnaby, are you signed up on the BCPOC forums? I'd love to see what you're doing with your car.

[WhiteDart]

Definetly interested in this. I would love to be able to ditch the disty without going with a standalone.

[KLZE Porsche]

does anyone know where a good forum would be for this kind of stuff?

Steve,

I didn't realize there was a seperate thread for engine electronics and this is the thread I just started in the other electronics thread:

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I am new to Megasquirt and I am trying to set up a special system and so I am fishing for any tips or help in doing so. Here is what I have:

Megasquirt II extra version 3.0 with daughterboard and StimJim.

New KL project with highly ported heads, KLZE cams, highly ported KLG4 intake and throttlebody, stock DE bottom end, 2002 KLG4 36-1 toothed harmonic balancer and VR sensor, KLG4 camshaft sensor, KLG4 crankshaft sensor, EDIS unit, expensive Tefzel shielded aircraft wiring and coils for Coil-on-plug. I believe I have to use the EDIS to go with a COP setup but I was told that there may be a way of doing individual channels with the new extra firmware.

I am looking for anyone with experience in this type of setup to give me some tips and hints. I am installing some bulkhead quick disconnect type connectors on the inside of the car and in the engine bay so that I can do quick ignition swaps because I am planning to test several systems I and another member have been working on. Your help would be greatly appreciated and perhaps enjoyed by other members later on.

Thanks,
M Perry

check out http://www.diy-efi.org some cool stuff there.

You don't need to get 6 MSDs as that can get spendy. VB921s, IGBTs (make sure u have dwell control) or even 6 HEIs would suffice and save you 90% of the cost.

I could use your help when ever you have a few minutes of your spare time. I purchased the MSII and now I need a little direction. Thanks!

[stoker100]

shaodome, thanks ive alrealy looked into that site (actually built the kit also) by the way im not planning on buying 6 MSD units lol. ill be dividing the MSD output to each coil so ill only need one MSD unit. also you dont need to worry about dwell with CDI which is why my kit will only work with CDI (without CDI it would require 10x more work and would not be as effective, i may do it after my CDI based one is finished just for a challenge)

KLZE Porsche, things are coming along well, ive tested the coils with a ghetto rigged 400VDC CDI equivalent circuit and they spark very nicely. this week ill be putting all the circuits together and seeing what the engineers at my work think before i build a test board.

ASword ill PM you when i get the chance, this has been a reasonably big project for me but i think ive done well with only needing power, ground, 1 hall effect sensor input and the ECU igniter output and thats it. its based on the 4017 IC which is obviously the divider but theres a lot more around it such as buffered inputs, latches, error detection, and the trickiest part is when starting.

this project wont "ditch the disty" because i have designed it based on some important criteria i set myself:
1) has to be a reversible modification
2) has to work on the stock ECU or stand alone without modification
3) has to be able to fire a 6cyl engine to 14,000rpm without loss
4) has to use stock sensors
5) has to have an error output (if there is a problem)
6) has to be reliable under high/low temperatures
(which is why ill be testing it on my car and preying it doesn't screw up) as you all know when messing with the ignition in such a manner its VERY easy to fire to the wrong cyl and just once at the wrong spot could be the end.

in a few weeks ill post a video of my car running on 5 disty fired cyl and one COP cyl if all goes to plan. thanks at this point have to go to KLZE Porsche as i was against the COP idea at the start but now its my obsession.

the simple fact is multiple spark capacitive discharge is the best way to drive a coil for a strong spark under extreme conditions and coil on plug allows for full power sparks to a higher rpm removing possible problem areas like the distributor. i thought at first i didnt want COP because i already had CDI, but the main reason i changed my mind is because the noise from spark plug leads severely effects nearby low voltage wires, i had problems because the spark plug leads cross over the distributor leads and the noise was causing misfires (+1 for crappy design disty). sorry fro the rant im finished now.

[ASword]

this project wont "ditch the disty" because i have designed it based on some important criteria i set myself:
1) has to be a reversible modification
2) has to work on the stock ECU or stand alone without modification
3) has to be able to fire a 6cyl engine to 14,000rpm without loss
4) has to use stock sensors
5) has to have an error output (if there is a problem)
6) has to be reliable under high/low temperatures

I agree with all of your points, although I'm a bit skeptical that the stock sensors would work reliably at 14K RPM!

My plan is to use an AEM C2DI, which is a dual discharge unit designed for direct ignition. My circuit will live in the cabin, and take the signals from the dizzy sensors and the ECU ignition signal. It is a PIC micro-controller board (professionally built) that keeps track of which cylinder is next and multiplexes the ECU's 5v signal to the correct AEM input.

I'm planning to use something like this as the coil (US$55 each x6): http://www.msdignition.com/coil_blaster_2_8230.htm

Of course this means I'll need new plug wires and this won't be a COP setup, just a non-waste spark DIS.



BTW: my car projects have seen zero progress in the last 5-6 years or so. Starting a family and buying a house tends to put a crimp on these things. This year might see the first progress in a while. I hope!

[KLZE Porsche]

i had problems because the spark plug leads cross over the distributor leads and the noise was causing misfires (+1 for crappy design disty). sorry fro the rant im finished now.

Steve,

This is why with my trial I am using ALL shielded Tefzel wiring in the engine compartment. If you use this type wire and then terminate one end as I showed you then it will eliminate the interference (in theory) This is why it is used in this same way in jet aircraft. If a jet experiences noise from induction then it could even be deadly.

BTW: my car projects have seen zero progress in the last 5-6 years or so. Starting a family and buying a house tends to put a crimp on these things. This year might see the first progress in a while. I hope!

I totally hear where you are coming from. I have been totally sleeping on most of my good stuff for the past couple of years with family, girls leaving home, trying to finish my degree and trying to hold down a job at the same time to make the house payments. So my intake manifold, titanium rods, supercharged engine, totally wacked out car and all have been on the back burner until recently.

As I told Steve, when I sit on this stuff and don't make progress then somebody else always beats you to the punch line. I had worked out a way to use biometric door locks long before they put them in the 350Z so now I am too late with that one. But now that I am back in action I am coming into swing very quickly. Between my last post and this one about my own COP trials I have figured out how to modify the MS-II to do the coil on plug just by reading up on it. I don't believe it has been done much but I intend to make it work. So I went ahead and ordered a bunches of EcoSpark IGBT's.

P.S. Steve, You can now purchase them directly from the Fairchild website. That is a change from 6 months ago. Several varieties are in stock and they are much cheaper than they were 6 months ago also. I believe when I first priced them they were over $5 apiece. I just ordered 14 of them for $33. WOW!! Also when I am finished wiring this car I will be able to install a pigtail on your version to to plug it directly up and put it to the test. You are going with full independant 6 channels where as I will be testing three versions of wasted spark against is so we can determine which method is better. I am testing a heavily modified version of the 626 G4 system and the MS-II coupled to EDIS and then a modified MS-II on it's own as a wasted spark system.

For those that are not up to this info yet - wasted spark is where there are only 3 channels so 2 spark plugs fire at the same time and thus the wasted extra spark does absolutely nothing. Steve is devoping a 6 channel system which has 6 totally independant channels so that only one coil fires at a time.

Debates have loomed between other people working on similar ventures as to which is better. Some have said that wasted spark is better because since the coil holds a residual charge due to shorter time between cycles that the coil reaches full charge quicker. And others have debated that a sharp, steep drop of the voltage in a seperated system to Zero volts makes for a better spark. It is actually the fall time of the induction voltage through the coil that determines the spark quality. So the EcoSpark IGBT's have internal voltage clamping which in-theory drop the voltage to zero faster.

So since there is so much debate on which is better Steve and I have decided to put the two to the test to find out by actual data.

[ASword]

So why is it you guys need IGBT's? Aren't you counting on a CDI to drive the coils for you? Messing with the high energy side of the circuit is hard core alright.

[stoker100]

im actually looking at using SCR's now, we still need something to drive the divided 1 channel to 6 channels and i plan on doing it buy turning on one of 6 SCR's to direct the CDI pulse's to the appropriate coil. SCR's have almost no resistance and can easily handle the high current and voltage pulse, while its not ideal having 500V DC going to a coil its better then 12v IMO. (and as you mentioned Asword you basically need to use a micro controller for a non CDI system otherwise theres too much work controlling the dwell etc) which is why i decided to go to CDI because i didnt want the added complexity.

as for commitments ive already got my house stuff sorted and i dont plan on getting married for at least a few years (and i wont have kids till after then) so now's the time for projects like this one.

if i went all out i would make a 6 channel CDI unit with an inbuilt divider but the problem is then the cost becomes much higher (for me) when i already have MSD and can use it to my advantage and later on if need be i can take that path.

[ASword]

I guess that's what I don't understand... why direct the 500V high energy signal when you can direct the low voltage / low current signal from the ECU. Just because you want to use the MSD unit you already have? Seems like a lot less work just to spring for a DIS CDI unit (MSD has one too, IIRC) and go the easier route.

[stoker100]

the MSD DIS CDI is for a wasted spark system, i wanted to make a true non wasted spark setup. the main reason behind my madness is either way the 500v signal needs to go to 6 individual coils, there is no 6 channel CDI (without wasted spark available under $1500) and so if i used the DIS-4 (without wasing spark) i would have to turn off one of the 2 plugs that would fire to make it a non wasted spark system (so either way theres work on the high voltage side).

remember either way with a coil on plug setup the 500V pulse has to go all the way through the wire to the coil no matter what i do so switching the 500V side just means i dont have to pull my MSD box apart and i can use any CDI available. let me know your thoughts.

[ASword]

The AEM C2DI (or the newer Twin-Fire units) supports non-wasted spark DIS setups. http://www.aempower.com/ViewCategory.aspx?CategoryID=78

Their FAQ has some interesting information, including saying that their box supports up to 14K RPM.

Oh, and this is a ~$550 unit.

[stoker100]

i didnt see that one before thanks. it appears its only for 4 or 8cyl though. anyway ill see how i go with my setup during the week and post back more info. another reason for working off the high voltage side is it allows the use of any CDI units or if i build my own i can easily incorporate that.

i made my own CDI test box in about 15min using a strobe light circuit charging a 1uF mains rated cap (gets to about 400V DC in 8sec), while its only food for about 5rpm it still allows me to test coils and my dividing circuitry away from the car so ill find out soon enough whats going to happen, either way its good for keeping my electronics skills up to date.