MS3X no start, no RPM signal
 

Hey guys,
I'm working on getting my NB1 started with my newly assembled MS3x (Thanks to WestfieldMX5, Brain, and countless others here).

Here's the trouble/details:
No RPM input under any conditions while cranking

2000 Miata,
MS3X V3.0,
1.4.1 Firmware
Wiring/build based on WestfieldMX5's site: http://westfieldmx5.devocht.com/mega...ro/ms3pro-pcb/
Base Map modified from: MegaSquirtPNP by DIYAutoTune.com (1999-2000 Basemap)
VR Pots adjusted:
main board R54 adjusted to 2.5v
ms3x board R17 adjusted to 2.4v (The max value I can get fully turning R11)

I've attached my map, a log, and composite log of the no-start condition. If anyone has a moment to check over my results it would be greatly appreciated!

based on the composite log, it looks like youre initially getting just the crank sensor (R54) and nothing.

Check to see if your TB is still turning your cams.

Thanks Brain:
cams turn okay.

Just to make sure I didn't screw anything up removing the AIDs the previous owner had (BRP supercharger with JR timing box & other crap), I put the stock ecu back in this morning and it fired right up.

Maybe I messed something up in the wiring harness and it's not seeing the signal from the sensor. Without any other leads, I'll start tearing into the wiring harness tonight and tracing connections from the ecu plug to the DB37.

Figured it out:

After checking the wiring harness 3x for continuity and resistance on the crank-in wire/pins (everything was fine), I figured i'd lower the output on R54 from 2.5v to 2.25v, and it worked. The MS3x is able to read RPMs properly now, and I was able to get a rough start/idle going with the base map.

Now the question is: What does this mean? Does that mean the crank position sensor is marginal (maybe the air gap is off), and the stock ecu was still able to pick it up even though it's a little out of normal range? Should I worry/care, or just call it good at 2.25v?

I go by the number of turns, I always ran into issues aiming for a voltage.

Thanks Braineack, sounds like there isn't an exact science to the setting depending on conditions, etc.

Just for reference when I tear into it in a few weeks to replace the timing belt/water pump whatnots, I'll measure the CPS gap and report back with my findings (the only thing I can think is maybe the previous owner had to replace the sensor, and didn't gap it properly so the threshold is lower than the expected 2.5v). Maybe it'll come in handy for the next guy having similar problems in the future.

Mine wouldn't run reliably on 2.5V either. I never scoped the signal, but I think it just doesn't make it above 2.5V very reliably.