cam sync pulse question

[sd1nl]

Hi,

I'm planning to make my v8 fully sequential with MS3. I currrently run semi-seq with a 36-1 triggerwheel. So I need a camsync pulse.

Because I like to keep the distributor and single coil I am planning to use a sensor wrapped around the nr2 cylinder ht lead, thus providing a suitable cam sync pulse.

Apperently old BMW's and Audi's did the same.

My worry is this: it is necessary to have the coil sparking otherwise I will have no camsync pulse, but will the coil start sparking without the camp pulse?

Is there anybody who knows this, because I have been desperately looking into the manuals but this seems something no one has done before.

Rene

[sd1nl]

Let me rephrase: is it possible in a single coil installation to get a spark before there is a camsync pulse?

Anyone?

[grom_e30]

as far as im aware it should work, when using sequential ignition the ignition starts in wasted spark then switches to full sequential when the ecu sees the cam pulse same with the fuel, starts in semi and switches to sequential so i think you will be fine with a single coil. my bmw originally had one of the sensors on the plug lead and i often wondered if that could be used as a cam signal.

[DaveEFI]

Hi Rene,
Since you already have a 36-1 crank wheel, the dizzy is only being used to send the spark to the correct plug? If so, you could grind all the teeth but one off the dizzy trigger wheel, and use the original dizzy VR sensor?

[sd1nl]

as far as im aware it should work, when using sequential ignition the ignition starts in wasted spark then switches to full sequential when the ecu sees the cam pulse same with the fuel, starts in semi and switches to sequential so i think you will be fine with a single coil. my bmw originally had one of the sensors on the plug lead and i often wondered if that could be used as a cam signal.

Ok, but I don't use sequential ignition. I use single coil. There is nothing in the literature about if the system starts giving ignition pulses before camsync

@ mr James Murray: could you help me out here?

[jsmcortina]

That's not a recommended configuration. I don't know if it would work.

I'd suggest following Dave's advice and implementing a real cam trigger.

James

[sd1nl]

I would have to modify the car for that. It is possible, but I would rather not.

I guess it should work, I just need to know if the ignition starts before the campulse, otherwise it would obviously not work.

Is there a way to find out? (as I haven't bought the MS3 yet, and I cannot try 8 cyl sequential on an MS2)....

[DaveEFI]

I'm slightly confused, Rene. You have a crank trigger wheel. But is the ignition still more or less standard dizzy? Ie, standalone - not controlled by MS?

[sd1nl]

I'm slightly confused, Rene. You have a crank trigger wheel. But is the ignition still more or less standard dizzy? Ie, standalone - not controlled by MS?

Crank trigger, ignition single coil, but controlled by MS. In theory you are right, I could use the trigger inside the distributor. I would have to sacrifice the distributor for that though....

[sd1nl]

I already have the ht lead sensor prepared....

image.jpg

[DaveEFI]

I'm slightly confused, Rene. You have a crank trigger wheel. But is the ignition still more or less standard dizzy? Ie, standalone - not controlled by MS?

Crank trigger, ignition single coil, but controlled by MS. In theory you are right, I could use the trigger inside the distributor. I would have to sacrifice the distributor for that though....

Don't see why. All you need to do is grind off 7 of the teeth on the reluctor wheel. The wheel is a separate item - I'll send you one if you need a spare. I'd remove the amp and take the tach feed direct from the VR sensor - but you could probably leave the amp in place, add a dummy load, and take the tach signal from that. (I'm assuming you have the DLM dizzy - but the principle is the same with others.

[sd1nl]

Been thinking about it and maybe you guys are right and am I making my life too difficult.

I might go for the stock vr sensor inside the dizzy. (If it works in combination with the ms3x board)

Which tooth would I have to leave on? The first pulse before the missing crank tooth of tdc of cylinder nr1 is the pulse of cylinder nr2, should I leave that tooth on? Bit confused about this bit.

[racingmini_mtl]

Which tooth would I have to leave on? The first pulse before the missing crank tooth of tdc of cylinder nr1 is the pulse of cylinder nr2, should I leave that tooth on? Bit confused about this bit.

That's the one I would use.

Jean

[sd1nl]

Does anyone know what kind of sensor is inside the stock rover v8 DLM8 distributor? Some say it is a hall sensor, but it has only two wire so it looks more like a VR sensor.

[DaveEFI]

It's a VR sensor. I have used it with other aftermarket ignition systems that are designed for a VR sensor, so it should be fine with MS. Its connector to the amp uses standard (IIRC 1/8") spade connectors, so easy to make one up.

I'm going down the same route as you - MS3X and sequential. Not fitted yet. So we'll be able to compare notes when done. Only difference is I'm using EDIS, and will fit a cut down dizzy to provide the cam signal. One difficulty is the fuel rail for later high impedance injectors. The stock ones have the in and out on the wrong side.

I've also decided to use a Bosch PWM idle valve instead of a stepper motor which fits to the plenum were the stepper goes.

[sd1nl]

Looks good the pwm. Think it will be better than the stepper I use.

Looking forward to compare msq's. Maybe we'll be able to meet up in the uk sonewhere along the line. I usually go there once a year in the Rover.

Rene

[sd1nl]

image.jpg

My engine bay. Stock at first sight.