Wingman703

Hello all,
I am in the process of putting an MS3 EVO into an NA(1994) miata. The engine(and sensors) are from an NB Miata(2000). This car was previously running and driving on an MS2 DIY a month ago. Megasquirt firmware is MS3 1.5.1.
My issue is I cannot get any sync when cranking. Not sync loss, just 0 RPM, no triggers in the diagnostic pages.
I have confirmed both the crank and cam sensors have 12v and are grounded to the MS3.
The engine speed sensors are both OEM NB Miata Hall Effect sensors and are wired as per the MS3 EVO manual, the crank signal wire is pinned to pin 6 on the white connector, the cam signal is wired to pin 25. I am using the FM 36-2 crank trigger wheel, and the OEM cam sensor arrangement. All other wiring was done per the MS3 EVO manual.
I have swapped both the cam and crank sensors for spares to rule them out as faulty.
Ignition capture is set to rising edge and "Miata 36-2" is selected as input type.
I am at a complete loss as to why I cannot get any sync and can only conclude there is a software setting specific to the MS3 I have missed somewhere as I cannot find a hardware issue. Any input is appreciated.

Attached is both my current tune and a datalog of a few seconds of cranking, although the only indication of cranking you can see is the change in Kpa.

Servaas Schutte

You first need to find out why we are not seeing CKP/CAS interrupt events. I would troubleshoot in the following order and report back your findings.

1. Check the output voltages from the CKP and CAS sensors using a multi meter on DC volts (should see the voltage change as you turn the motor over by hand and teeth pass by sensors)
2. Make sure ECU cam and crank circuits are setup for 2x hall inputs (Read the manual or call DIYAutotune)
3. Setup indicators so you can see the state (high/low) of those sensors in TunerStudio
4. Get it running wasted spark/semi sequential using just CKP
5. Change to COP/Full sequential and use Miata 36-1 spark mode

Wingman703

Issue ended up being pullups. Needed a 1K resistor for each signal line. Once installed it synced and fired right away.

curly

iTrader: (25)

I was going to suggest this until I saw you solved your problem, but I'll say it anyways: I've had two cars recently with massive sync loss issues running FM's 36-2 wheels. No issues with FM's wheel itself, it is the only one I'd currently suggest to anyone looking, but factory spec of .035" seems to be too big for MS, at least the two MS3 Basics I experienced this with. Gapped both cars to .01-.02" and sync loss issues disappeared, and I should say that neither had issues at idle or free-revving. YRMV.

Wingman703

Yes, I've had similar experiences with 36-2 trigger wheels. Normally mine would "half sync" at start, fire twice then sync error, fire twice then sync error, coughing just enough to make me think it was about to go but never catching. I don't know what my "spec" is now, I shine a flashlight under the sensor and tap it in towards the wheel until only a paper's thickness or less remains of light. Holds sync to 8K like that.