MicroSquirt.com read only forum (Jan.15,2018)

I'm assisting in the project that natedawg is working on and we are still having some problems with the rpm signal. MegaTune seems to be registering 2 pulses per revolution. The sensor we are using is a SUNX PM-F24-R. It's information can be found at the following link

http://www.clrwtr.com/PDF/SUNX/SUNX-PM- ... ensors.pdf

Our wiring of the sensor is the black wire to OPTOIN-, brown wire through the relay that powers the Megasquirt, blue wire to the sensor ground, white wire to nothing, and OPTOIN+ to a 12V source through a 1K-Ohm resistor.

We tried changing the number of cylinders to 2 from 1 under the Injection Control but it didn't seem to do anything to the rpm or to the fact that the injector is squirting every revolution instead of every cycle.

These seem to by our last two problems to overcome before we can start tuning our engine so any information would be GREATLY appreciated.

To help I need your msq and confirm the following engine info:

1 cylinder
4-stroke
1 slit on a crankwheel disc

The engine info you listed is correct.

The msq file we are using is attached.

Additionally, because of limits on our project, the only other sensors we are using are the IAT and Throttle Position with the possibility of a Heated O2 sensor(during tuning only and removed during operation).

We elected not to use a CLT sensor since the engine is air cooled, and left off the map sensor because we were told that the Alpha-N tuning would be most appropriate for our purposes.

Lastly, I'm not sure if it is important but we are using v2.886

"We tried changing the number of cylinders to 2 from 1 under the Injection Control but it didn't seem to do anything to the rpm or to the fact that the injector is squirting every revolution instead of every cycle."

The configuration you have assumes a distributor, so the rpm is double what it really is. The solution to this problem, as Matt said, is to change no. cylinders to 2. This will not hurt anything and I believe it will solve the rpm problem. BUT, I think it didn't appear to work for you because you didn't burn the change and then cycle power. The reason is the RPM coefficient is calculated once at the start, because no_cylinders is not a tuning parameter, but a configuration. The only way changing no. cylinders to 2would not affect rpm is if you didn't burn the change, and then re-cycle power to the ECU.

I believe the 2 fuel injections per cycle will be solved by (on one of the fuel menus) setting "Alternating" instead of the "Simultaneous" in your msq. This will stiil inject every cycle, but on alternate injectors, and you only have 1 injector for your 1 cylinder, so Inj1 will only occur every 720 deg.

Thanks for your help! Cycling the on/off was what I needed to do.

I'm still having problems with the fact that it is injecting twice per engine cycle(once per revolution) I tried as many combinations of injections per cycle, injectors, and simultaneous/alternating that I could think of. It would never let me do 1 squirt alternating with 2 cylinders and 2 injectors which is what I figured it needed to be. Do you have any other ideas of what I could do to rectify this problem?

Thanks again for all your help.

I was just changing some settings on MegaTune and I noticed that the reason it is squirting 2 times per cycle is that while I was testing it I was staying within the cranking rpm. Once I get out of the cranking rpm it switches to injecting every other rotation. Thanks again for all your help!