Mercedes V12, can MS control this existing ignition?

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Tinkers Toy
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Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

I have my 1994 V12 Mercedes running smoothly on Megasquirt 3 & MS3X. Right now the car is running fine using semi-sequential fuel only on Megasquirt and the ignition and knock is still handled by the Mercedes ECU's. I have a problem with the Mercedes ignition, I do not believe the Mercedes ignition modules are advancing the timing. Since the fuel ecu,'s are not being used I think the ignition is in limp mode. The car runs ok but it lacks the power it should have. Phase two is to add coil near plug ignition by adding GM LS1 coils and a trigger wheel in place of one of the distributor's on the front of the cams. At that time I'll go fully sequential fuel as well but that needs to wait till funds improve. Existing Mercedes ignition consists of two separate coils, each coil goes to the center lug of a 6 lug distributor cap on the front of each exhaust cam. I'm assuming the 2 coils fire 60 degrees apart from each other and each coil fires every 120 degrees of crank rotation. My logic is 120 degrees x 6 cylinders is 720 degrees of crank revolution, multiply that by 2 distributor caps equals 12 cylinders.

Hopefully you're still with me which leads to this question. Can I trigger these two coils with the existing MS3 /MS3X that I'm running at this time?


Here is my build information.
MS3, MS3X, 4 channel driver board.
two GM cable driven throttle bodies using one of the integral idle stepper valves and blocking off the other and using one of the throttle position sensors and removing the other. A solid connecting rod ties the two throttle bodies together.
GM coolant temp sensor
GM air temp sensor
36-1 crank wheel and hall sensor (no cam sensor for Megasquirt at this time, the cam sensors are only connected to the Mercedes controllers).
Innovate LC1 wideband O2 sensor
dontz125
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Re: Mercedes V12, can MS control this existing ignition?

Post by dontz125 »

Yes; there is a 'Dual Dizzy' mode. Basically, you have two spark outlets, and they alternate back and forth A-B-A-B-A-B, firing each dizzy in turn. I'm assuming the existing dizzy coils are dumb two-wire units, so you'll need to add coil drivers such as the BIP373. I make a two-channel unit, and DIYAutotune offers their QuadraSpark.
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
Tinkers Toy
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Re: Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

OK thanks for the reply. I see the spot in Tuner Studio to set the outputs to dual dizzy but I can not find any more information in the manuals. Knowing that my MS / MS3X with a 4 channel driver is set up for 12cyl, if I set it to dual dizzy, which outputs on MS become the two outputs for the two coils? I know I have to go through an igniter module, there is plenty of information on that.

Thanks again!
slow_hemi6
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Re: Mercedes V12, can MS control this existing ignition?

Post by slow_hemi6 »

Output wise it's going to be a lot like the 1uzfe motors. Found this link with an answer from Matt. http://www.msextra.com/forums/viewtopic ... 48#p308348
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
Tinkers Toy
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Re: Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

Thanks for the link. I'm still trying to figure out where my two spark outputs would be connected. I have MS3 / MS3X & 4 channel driver. When I assembled my ECU for 12cyl spark I used 4 of the spark outputs from the main board for ignition I,J, K and L. From what I can gather setting "Dual Dizzy" will use spark A output from the top of R26 and spark B from the top of R29 on the mainboard. Since I use the top of R26 as spark I and the top of R29 as spark J, I should expect to connect to spark I & J on my particular setup. Does this sound reasonable? I'll go in the shop tomorrow to investigate my theory while I await delivery of my BIP373's.
dontz125
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Re: Mercedes V12, can MS control this existing ignition?

Post by dontz125 »

Dual dizzy fires A and B, BUT on the Ignition Settings screen you can select "use MS3X" or "use LEDs". Choosing the second option means the MS ignores the expansion board, and just uses the MS2 style outputs.
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
Tinkers Toy
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Re: Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

That is good info to know and thanks for your help, does it ignore the entire expansion board or just the ignition side of the expansion board? My fuel is still being handled by the MS3X expansion board.
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Re: Mercedes V12, can MS control this existing ignition?

Post by jsmcortina »

The setting for ignition output only changes the ignition output. Fuel has its own setting.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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Tinkers Toy
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Re: Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

thanks for all the information. I think I'm ready to tackle this next phase. I'll report back with all my findings when I get converted to the MS ignition.
Tinkers Toy
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Re: Mercedes V12, can MS control this existing ignition?

Post by Tinkers Toy »

ok, the duel dizzy worked great with my homemade 2 channel ignition module, however, I had a distributer cap and rotor issue so at the cost of 2 caps and 2 rotors I just converted to 12 each LS2 D585 coils and eliminated all the Mercedes stuff and saved myself $100 bucks after the cost of the coils and wire boots.
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