Cedric_w

HI Guys,

Sorry for the thread revival. But I'm facing a similar issue with a MS3 and VVT engine installed in my NA. Revs up perfectly fine up to 4300-4400 rpm and at that point it looses sync and acts as if it hits a limiter due to the sync loss. It recovers again after some time. the Sync loss reason is given as 31 or 32 depends. Which indicates an issue with the cam
- 31 = Miata 99-00 - 2 cams not seen
- 32 = Miata 99-00 - 0 cams seen
Although the composite log seems to show a missing crank puls. I copied the data into excel and could indeed notice a change in the trigger sequence (cam signal).

Things I have checked:
- Checked ground connections, add verified that they were good.
- Both cam and crank sensor are good.
- Crank sensor gap is set to spec (credit card thickness)
- I have no noise filtering on.

I have added three logs and composite logss which show the behaviour I mention at 4300 rpm give or take. Also added the excel where I looked at the data from the composite log around the sync loss point.

as for the sync loss locations:

- 2023-01-07_14.55.04.csv Page 11, time: 25321.71
- 2023-01-08_11.27.29.csv Page 42, time: 118196.51
- 2023-01-08_13.20.27.csv Page 90, time: 269201.38

This was all test on jackstands/stationairy so no load on the engine. Bit at a loss as to what it could be exaclty, tried jiggling the connector of the Cam sensor when stationairy but that caused no problems at all.
I have a trackday planned at Spa Franchorchamps the end of March and still need to get this thing run in and mapped, so on a bit of a schedule. :/

Any help would be appreciated.

HowPrayGame

What MS3 version do you have? I am a few years rusty now but IIRC adjusting the physical trim pots on the megasquirt to process the crank sensor sometimes fixes sync loss in the event that it occurs with good cam/crank sensors, that are properly adjusted. As I have an MS3 Basic I dont have physical trim pots, some auto adjusting thing of some kind. Check your crank log to see if the crank tabs of 1 -2 -1 -2 etc correspond to 4 lines from the other sensor every time. If this isn't the case sync loss happens as the ms cant sync the cam to the crank rotations.

Cedric_w

Also a basic version without physical trimpots here, that's one of the first culprits I was hoping to find.. but allas the basic ones don't have them.
As you can see, this is at around 4500 rpm that it drops two pulses on the crank sensor, atleast that's what it seems like. although the sync loss reason is given as 31 and or 32, this instance it was 31.

Going to try swapping sensors once again with a friends, eventhough mine are new oem ones.

Cedric_w

issue resolved, ECU was the culrpit. bought a new official MSlabs MS3 and it was gone.