MoTeC Global Forum

We are using M400 for datalogging purposes in KTM 380 2-stroke dirt bike. We have tried to find suitable set-up for the engine but there seems to be some problems, RPM-triggering is making some problems for the whole unit and PC-communication. If we use -1 cylinder value and 61 ref/sync mode which I think is ok for the original sensor, there is severe problems; PC-loses connection as soon as engine started or without PC-connection datalogging contains very strange, mainly zero values of many datas. If cylinder value is changed to 4 them everything seems to work much better. All connections are checked and this seems to be only set-up issue.

Any idea what is wrong?

VPV-Motorracing
Finland

Is CAN Bus terminated at least on one side?

I know its off the topic, but what are you using for EGT?


What sensor on the bike are you using for the trigger to the ECU? The same as the CDI trigger? or did you add a sensor.
I think the CDI trigger might be exceeding the input voltage limits of the ECU. Did you measure p-p?

We use the original magnetic sensor, it is not KTM-part because we have changed Kawasaki coil and flywheel to this engine, the Motec input is directly parallel to Vortex CDI we use currently for ignition. I have looked that the signal level is very high, say 50V p-p but I haven't found any specification what is the maximum. As an electronic designer I have been thinking that this input is protected because it is very easy; current level from magnetic sensor is rather low and many magnetic sensors can give high voltages.

CAN-bus don't have any load resistors, cable from M400 to UTC is about 1m and the cable from UTC to PC is the original delivered with UTC. PC uses XP and is 1 year old HP. I'll add this resistor to the bus

But the strange behavior which for me says this is mainly not communication issue is that if the trigger signal is not connected everything is ok and only very seldom there is some communication errors. Also when I change the setup to that 4-cylinder mode the communication errors become very rare. This one cylinder -1 setup might make more communication and that's why the communication corrupts more easily, needs more investigation....

EGT is measured with 3/100mm silicone cable K-type sensor and is amplified with my own company prototype amplifier; 0-1000C -> 0-5V differential input and output, with cold junction compensation

I'll make some more testing today

VPV

I think that you have to put resistors on both sides of CAN line.

I made some further test and now I'm 99,9% sure this is a software bug, or my unit have some problems in it.

I made a very short 100R equipped twisted cable from M400 to UTC and located it far from ignition parts -> No effect on behaviour

I configured the M400 to output special RS-232 data at 9600 baud and received it using hex-capable software. When M400 totally refuses to connect PC it simultaneously stopped sending RS-232 stream. Only after power-off-on reset it started again. This same happened even if there was no PC-connection

After some hang the Motec software said that the file in M400 doesn't match file on PC -> Flash oh the M400 has corrupted during hang

I made also some testing without ignition on; I used screwdriver or rotated engine back and forward by hand equivalent to 0-120rpm. During this test the Vortex CDI don't make any sparks so no EMI. Even with this test the system totally hangs. I also logged the trigger signal and it was something like 1-3V, so no overvoltage during this test

And finally I made again the test using 4-cylinder setup without sync-sensor. I started the engine and run it several minutes without single communication problem. During this test the signal from sensor is over the limit, about +-30V, so this overvoltage seems to be no problem. Also datalogging was very clear and correct

System don't have any high current draw systems connected, no injectors etc. Only wide band lambda option is on. Power comes from 14V LiFePo4 2.3Ah battery capable to feed 70A for 10s

What do you, Motec engineers think of this?

VPV

This mode needs to have a minimum number of cylinders set to 4. You will need to find another trigger method.

Thanks! This solved the problem. if I'm right there is no trigger method which can use the original sensor and trigger wheel so I need to make a new trigger system for the M400

Regards
Veli-Pekka