MoTeC Global Forum

Hi,

Following with the previous thread I wrote, the ECU was finally damaged. We've already solve all the "hardware" problems, but now we have some questions.

We have all sensors and actuators property wired, the problem now is that in test outputs, both ignition and injection are working, but not when cranking (neither spark nor injection) .

My thoughts were first about input sensors (we just use TPS and Engine Temperature), so I wired all the main sensors thinking that maybe without one of them the ECU wouldn't allow ignition & injection.
After that (of course without success), I saw in diagnostics errors that MAF, FP, OP and MAP sensors are always in error (even when the channel is enabled and the sensor wired).

Thus, the ref/sync synchronization is also in error. We have a Ref/sync mode 8, without Sync sensor, but curiously the sync sensor is always feeded with 3.86 volts (I read it is a pull-up, but I'm not quite sure if that is correct)



Any hint or idea about this?? Thanks in advance

The ECU will not trigger injector or ignition outputs if you haven't achieved "Ref/Sync Synchronised" on the View Diagnostics / Status screen.

Work on that, remove your plugs so you can spin the engine on the starter reasonably quickly. Use Utilities->Ref/Sync Capture... to see what the ECU is seeing. Review the various webinars on Ref/Sync setup, and post your Ref/Sync Capture here for us to look at.

Hi again,

I think I attached the problem a little closer. In this moment I have spark and injection, that problem was solved touching the tooth ratio (above 60 is okay, but below that number the ECU is not Synced).

The main issue now is a little more weird. With the spark plugs removed from the engine, there is injection and ignition, but when I put them inside again, the problem appears again. The ref signal is synced in both situations, so I captured the signals with and without spark plugs.





As you can see, there is some fluctuations on the frequency of the ref signal with the spark plugs inside (which I consider normal due to the engine compression).
What I consider strange, is the fact that with compression, the engine cranks around 280 rpm, and the ref signal voltage circa 5 volts; and without compression, the engine cranks at 580 rpm and the signal voltage 2.5 volts. Correct me if I'm wrong, but theoritically in a magnetic sensor, the higher rpm, the higher voltage of the sensor.

On the other hand, is impossible that the engine cranks faster with compression than without them. I considered the possibility of the Ref sensor missing some tooth, but the signal wouldn't be as clear as it actually is.

I touched a bit the Mag filter, always between 0.1 and 0.3 volts. With this I achieved sometimes one first injection and spark (just one), but I'm not pretty sure if that was a coincidence or not.

I was also thinking in adding a resistance to the ref output, to decrease the 5 volts to 2.5 and having "the same" signal as without spark plugs. Would it be a solution?.

Thank you once again.

Sorry, it seems that the pictures are too big and they dont fit entirely.

Can you post a picture of your trigger wheel -- I wonder if the teeth aren't too small for the mag sensor and that's why the voltage goes down as the speed increases -- they aren't wide enough, or is this the stock engine trigger setup?

What is the gap from the sensor to the trigger wheel? Normally we see voltages less than 1-2 volts when cranking, so I'm surprised if you really are seeing 5V levels while cranking with plugs.

Since the engine slows so much on the compression stroke, what does the ref mag levels table look like? I think you should have a value of 0.2 at 0 RPM and perhaps 0.25 - 0.5 at 500 RPM.

Do not put resistors in your mag sensors -- the ECU is perfectly capable of dealing with the voltages produced.

BTW - in your other topic you said this was a 2-cylinder engine, but your traces look like only one cylinder has compression (and perhaps too much!). Is your starting battery fully charged?

I think we could be more useful if you would post your ECU configuration file and the actual RefSyncCapture file (*.rsc2). You may have to compress those into a zip file to upload.

The different cylinders speeds might be because of the battery level, it was almost dead at that moment

I didn't try changing the trigger sensor gap, but I don't think it'd make a change, if the stock ECU recognises the signal perfectly, this one also has to do it.


I attached the ECU files, let's see if I made something wrong on the parameters setup.

Please describe your engine & trigger setup in more detail.

From the M84 config this is a 2 cylinder, 2-stroke engine with the trigger mounted on the crank shaft.

A few problems -- you have the Ref Sensor Edge Polarity set to Rising Edge, but your Ref/Sync capture shows a falling edge signal. Either reverse the leads to the sensor, or change the Ref Sensor Edge Polarity to Falling Edge. You will need to reset the CrIP value with this change, so verify the timing with a timing light with the plugs removed.

Next, the Ref Mag Sensor Levels table is all zeros! This is the arming voltage before it will look for a signal to cross the ref-trigger voltage (which is correctly set at 0V). Open up this table, and press F1 and read the help about how to set the levels, using what you find in the Ref/Sync Capture window. The default table provided in the help would probably work for you:

RPM 0 250 2000 20000
Level 0.3 0.3 2.0 2.0

Don't waste your time trying to start the engine with a discharged battery -- get it charged up, and leave it connected to an external battery charger while you are trying to start the engine and are working with the ECU.

Lastly, your Ref/Sync with plugs installed shows some cycles with basically no compression -- is there some kind of compression relief valve designed to help starting (I know some bike engines have this) that would explain that?

Hope that helps!