M4 / Two stroke sync ?

[aurinkola]

Hello there
I would be happy the get some assistance. This is my set up:
two stroke,two cylinders ,4 injectors (two in pairs),crank trigger 30- 2 teeth.magnetic. Engine is big bang (both cylinders have same TDC.
I want to be able to tune the cylinder sparks and fuel seperately for each cylinder. As far as I know the engine should be syncroniced with sync sensor. Is it possible to put sync sensor to two-stroke ? Or is there another trick to do ?
With regards
Mike

[RossB]

What engine is this???

If you set your number of cylinders to -2 for a 2 cylinder 2-stroke then set your oddfire TDCs to 0 and 360 it should work ok. You would need to use 2 seperate coils. The problem may be starting though as you will need to use an additional tooth or missing tooth mode to syncronise. If you have big fluctuations in cranking speed because of the single compression event you can have problems with these modes.

[aurinkola]

Hi Ross
Thank You for the reply.
It is italian 500 cc two-stroke with two cranks. The cranks rotate in opposite directions.
I have tried the set-up You recommend it starts okay and obeys the separate trims BUT the Bosch inductuve amplifiers get dangerously hot and the amplifiers freak out. I am using two of Your MEC coils. I think because the system has no sync. Am I right ?
How to assemble the sync in right position relative to ref ?
One british lad had made it work with M800 without sync (to get separate cylinder trims) just by setting TDC split. What do You think ?
Mike

[RossB]

You do not need a sync sensor on a 2 stroke engine, in fact there is no way you can run one as the 2 stroke engine has a 360 degree cycle. What crankshft trigger wheel do you have on your engine? You will need to use 2 coils and 2 seperate ignition modules (not a dual channel module) Which Bosch module are you using?

[aurinkola]

Hello Ross
I am using Motec number 41200 inductive two channel amplifier (200 Series Bosch). I cannot understand why it hot HOT with Your set up : -2 cylinder,oddfire 0/360 degrees, falling edge,injectors first cyl/1 and 3, second cyl /2 and 4.coil dell 2.8 milliseconds,mec inductive coils,Marelli magnetic pick up 680 ohms connected to ref, trigger wheel 30-2 teeth (actually 28 teeth so two missing, mode 81)
Is it so that You cannot tune injection timing because sync is not possible ?
Mike

[RossB]

I am a bit confused now... you say that this is a 2 cylinder engine but you refer to cylinder 3 and 4???
THe 200 module is not what I would recommend as it is not designed to fire on both channels simultaneously. I would recommend 2 seperate single channel modules.
YOu should be able to tune injection timing ok. Have you checked, with an oscilloscope, that you are triggering off the correct edge of yopur crank trigger? The first edge after your missing teeth is your index tooth. The CRIP is the number of degrees of crank rotation from this point to TDC and the ECU calculates TDC from this. If you trigger off the wrong edge of the sensor the ECU will have trouble detecting this index tooth acurately and you will have timing isues.

Can you post your ECU configuration and I will take a look at it?

A photo of this setup would be interesting too!

[aurinkola]

Hi Ross
Sorry for my unlogical way to epress the injector wiring. This was My odd fire wiring :
Pin2 /Inj 1 first cylinder primary throttle
Pin 14/Inj 3 first cylinder secondary throttle
Pin 3/Inj 2 second cylinder primary throttle
Pin 15/Inj4 second cylinder secondary throttle
Could You give me email addres for sending pics.
Mike

[RossB]

You can post them on here.

[aurinkola]

Hi Ross
I think I found the problem.
The magnetic trigger is falling edge type (goes to negative from positive at strike). We had in the beginnng edge/wheel mode 81 that is for rising trigger. It is changed to mode 83. I did not know know that M4 is so good that with this mode the engine will be synced. Good stuff. Now I have ignition and fuel trims to each cylinder.
Thank You