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

Hi I am with the University of New Mexico's Formula Society of Automotive Engineers(FSAE) 2010 team. We are trying to run a 2007 Yamaha Phazer (Genesis 80FI) engine on our car with the Microsquirt ECU. We have been trying to start the engine for a couple weeks now with no success. We have spark in both cylinders as well as fuel injection. The problem we are having is the engine does not like to turn over when we crank. Once the rpm reach around 600 it immediately drops back down to 0. I have attached our megatune and would like some help verifying and our settings. We also obtained the following datalog and need help interpreting it:



Thanks in advance.

Quick thing to do ... try lowering your cranking RPMs they're set at 750...I think your starter turns at less than 400, and I would think you'll not see more than 250 on a closed throttle. I don't have any issues with idling at the moment, and mine is a FZR1000 derived lump, cranking rpms=250 for me.
Your cranking PWs are well high (compared to mine) as well. You're probably flooding the engine with fuel, re comments about "doesn't want to crank" Just checked your engine out, it's essentially two YZ250Fs stuck together, and it's got an electric decompression system, so the starter probably does make more revs than I thought, but just another thought, if it's hard to crank maybe this decompression system is not connected.

Thanks 24c, we'll look into it soon. However, I need some clarification on the datalog, because i'm getting contradicting information in the forums. What are the causes and solutions for the trigger +/- decreasing, losing tach sync (RPM => 0) and erratic fluctuations of deltaT?

unm2010tim wrote:What are the causes and solutions for the trigger +/- decreasing, losing tach sync (RPM => 0) and erratic fluctuations of deltaT?

I don't know your engine, but I assume it has a toothed wheel like an R1 and a cam sensor. My trigger± & losing tach issues were interference from one VR sensor with the other, and it doesn't matter what code I run, it does it consistently. I now have a small signal diode on the shared ground, and a resistor across the cam sensor. I now get no loss of sync driving my stock coils from 1100-11000K using a cased MicroSquirt and the built in drivers.

unm2010tim wrote:What are the causes and solutions for the trigger +/- decreasing, losing tach sync (RPM => 0) and erratic fluctuations of deltaT?

These are all the same thing. When you miss a tooth detection, or get a false tooth detection, deltaT doubles/ halves, this results in a missed/ extra tooth (trigger-/+), and if it happens twice in a row, you lose synch (meaning rpm jumps to 0).

It's been a year or so since I worked on UMaine's Phazer so I can't say for sure what we did, but I know we followed the advice of those on the forums and wired something into the VR sensor circuit to "pull up" the voltage. I think it was some combination of a diode and a resistor, can anyone else explain that change? Sorry, it's been awhile since I looked into this. I'd try that if you haven't yet. I've attached the .msq file that worked for us in case you wanted to look at it and compare to your own.

In the UMaine snowmobile, did your team use an ignition module? We are not using one, we have our spark output set at "going high (inverted)" at a dwell time of 3 ms. We do have spark, but it is weak. Would an ignition module alleviate this problem?

In addition, we obtained the following oscilloscope data:

http://i43.photobucket.com/albums/e380/ ... c_data.jpg

Due to a limited knowledge in circuits:
What are general guidelines in implementing diodes and resistors into our circuit?
How do we know what resistors and diodes to use?
What influence would a diode or resistor have on our oscilloscope data?

I believe we need to implement a voltage "pull up" on our cam signal by using a diode and add a resistor to our crank sensor to get a more consistent signal...is that correct?

Finally we got our engine running! The cause was due to a diode which we placed in the VR+ signal line. The diode greatly affected the sinusoidal waves from the crank sensor and as a result the signals crossed zero at random times thus causing the trigger +/- and deltaT to change and as a result our RPM constantly dropped to zero. In addition, we did a voltage pull up on the cam signal to create the square wave which allowed us to use the falling cam sync dual spark option.

However, we ran into another strange problem. The engine would idle for a couple seconds, then it would reset and cause our RPM to drop down to ~1500RPM and regain RPM when the ecu reconnects. This would happen a couple times until the engine dies. We determined the problem to be the connection to the laptop. If we disconnect the ecu from the laptop, the engine would idle smoothly with no ecu resets. Why would the ecu reset when it is connected to the laptop? We tried shielding the serial cable but that didn't help.

Thanks in advance.