M&W pro12 with SM4

[yrkesman]

Is there any special options that should be used with M&W pro12 cdi ignition in 4cyl engine with coilpack? Ign delay time for example, what should it be? Or dwell, is 2ms okay? I have a problem with timing drifting at idle and I'm trying to find out what's causing it.

[Chris]

What is the engine ? what is the trigger configuration, what trigger edges are you using ?

Chris

[yrkesman]

What is the engine ? what is the trigger configuration, what trigger edges are you using ?

Chris
The engine is 2L Cosworth YB. The trigger setup is 36-1 crank trigger with inductive sensor, since I had EDIS4 before and hall sensor on cam positioning. Autronic SM4 has "Ign trigger edge" configured as -ve edge and M&W pro12 has falling edge trigger configured in it. It has coilpack which is originally from Ford zetec engine. I tried today another coilpack with no difference. I used scope today to make sure that the crank trigger sensor was connected corretly. It seems that the ignition is moving +- few degrees from the ignition angle I have adjusted. I tried today without twinspark on M&W but that didn't make any difference. The ecu has 1.06 software in it. I used idle ignition table with 16degrees in it when testing and idle ignition angle mean showed 16deg all the time when testing. I'll have to double check everything since I'm going out of ideas soon.

Here's my current cal file:
http://kotisivu.dnainternet.net/jtuomol6/sekalaiset/160208_KOLMA.CAL

edit: the engine has 5mm longer conrods and standard cams that are timed so that inlet is open 1mm at TDC and exhaust 0.8mm at TDC if that makes any difference. It does idle quite smoothly but it could be better. I'm also having problems with the idle valve when engine is warm but that's another story. When testing the ignition I had "constant" pwm fed to the idle valve.

[MRMRacing]

The Ign Delay Time only changes the delays for ignition and if wrong delay the ignition should move at different rpms with same ignition set.

For the purpose of this thread the v1.06 and onwards have an additional parameter called the Digital Angle Filter. When set to Fast it operates the same as earlier SM4 & SMC / SM2 CPU's. When set to Slow the prediction is averaged over more Cylinder Pulses to minimise scatter.

You could try to change this option, and how much are ignition mowing at idle? Is it OK at all other rpms?

With all cdi´s it is strongly recommended to use twisted wires to all coils and for the power & ground wires to cdi. Never ground CDI at same point as ECU.

You could also test a Bosch 2-channel module instead of the CDI just for verify, change to -Ve dwell in software.

[yrkesman]

Okay thanks. I'll let you know when I have time to test it more.

[yrkesman]

I tried today the slow option but I didn't notice any difference with it. It's hard to tell how much the ignition does change, but I gues that it is something like +-2degrees at idle (900rpm), 2000rpm is is bit better and 3000rpm it seems to be spot on. It seems that with more rpm it does get better.

Coil wires are twisted and CDI is grounded near the unit, so it's not grounded to the same point as ecu.

[yrkesman]

Could the problem be my cylinder I/P lead angle, 118deg with the 36-1 trigger wheel? My Sync/Cyl percent is 25-30%

[Chris]

What timing light are you using ?

Chris

[yrkesman]

What timing light are you using ?

ChrisSome cheap, can't remember the name of it. I could try some other timing light.

[Chris]

Some cheap, can't remember the name of it. I could try some other timing light.


It is sometimes a problem if you use a "dial back" or digital timing light that shows offset from tdc.

A standard style timing light should give you no problems.

Chris

[yrkesman]

It is sometimes a problem if you use a "dial back" or digital timing light that shows offset from tdc.

A standard style timing light should give you no problems.

Chris
It's standard timing light, the only one I found at the time. I think it was Trisco, if I remember correctly.

[Wroom]

Are you using multispark on the pro12 while testing with the timing light?

[yrkesman]

Are you using multispark on the pro12 while testing with the timing light?No, I took it off.

[Wroom]

Ok. Just checking.

Regarding quality and reliability on timing lights - It's a hazzle! :eek:

I have a timing light that give a steady and continuous measurement up to at least 100 sparks/sec before it starts to skip or burst the flashes.
It never doubletake pulses on speculation, and it will not flash on erratic ignition, so if one has a steady timing indication one knows the timing is reliable.
Since it does not burst, it will show every ignition point, and one can se errors as multiple readouts on the scale, so one can easily find problems like uneven crank pulses on waste fire engines.

Bought it on recommendation many years ago, and dread the day i have to replace it. Not easy to find reliable timing lights.

Maybe we should have a separate thread about recommendations on timing lights?

[yrkesman]

I tried today different crank trigger sensor gaps without any difference, 0.5mm, 1.0mm and 1.5mm. I swapped also plugs so that 1&4 are now in 2&3. I'll hopefully get the hall sensor next week so I can try if it makes any difference.

[yrkesman]

I did today some more testing with scope and the trigger signal from Autronic to M&W looked fine. I tought that there was something wrong at first, but it was just a bad connection on scope. So that seems also ok.

I noticed that MSD CDI should have 2.5ms dwell time/pulse, what's the reason for it needing longer pulse? Is 2ms enough for M&W?

[Wroom]

There is nothing special noted about trigger pulse lengths in the manual.

But 2 ms pulses must be more than enough.

[yrkesman]

There is nothing special noted about trigger pulse lengths in the manual.

But 2 ms pulses must be more than enough.
Okay, thanks.

edit: I got reply from M&W that the trigger signal can be as short as 0.2ms and still trigger reliably.

[yrkesman]

Oh boy, even more problems now :) I got the 1GT101DC hall-sensor and got it finally installed last weekend. The problem now is that the hall-sensor signal disapears after first missing tooth at the 36-1 trigger wheel. I measured it from the sensor with oscilloscope. After the missing tooth the second pulse comes when the missing tooth comes again. +8V signal from ecu to sensor is fine. I wonder if it is the sensor that is no good. I have tried sensor gaps from 0.5mm to 2mm without any difference.

[yrkesman]

I tried ~3mm sensor gap and it works now. It must be my trigger wheel that is little smaller than my cranckshaft pulley. I think that's the problem. I'm not sure if the sensor swap made it any better, maybe little. But I think I can live with it now. I'll make better pulley-trigger disc compination next time the pulley is off.

[yrkesman]

I think I have finally solved my ignition issue. I changed my IP lead angle from 100deg to 60degree and changed the divider offset so that I got correct spark. Now the ignition is almost perfect :) Interesting how much difference it made.