My Reverent-built MS3 has been running my 2004 VVT in a 94 chassis for the past 18 months and 20K miles. Within the last 3 weeks I suddenly have been getting a very intermittent Sync Loss. This will happen once or twice in an hour drive, but it is not consistent. The MS3 will lose sync (reason 32), the fuel pump relay will click off/on, and then sync is quickly restored. Here is a screen-shot of the loss of sync caught with the sync error logger. CSV Attached.



What I have tried so far.
1) Replaced cam angle sensor with a new unit. No change better or worse.
2) All grounds cleaned. No change better or worse.
3) Adjust crank angle sensor a little closer. No change better or worse.
4) Noise Filtering - Turned tach period rejection on. I went three days (4-5 hours driving) with no loss of sync, but just today got one this morning. Placebo? or maybe slight improvement.

I have a new crank angle sensor on order, this is the last obvious item I see left, unless I am missing something basic?

 

Totally different ecu but my DIYPNP would have a hiccup like that. It started well after I built it and went through a couple iterations. It started one day and I thought it was the main relay. Then the ignition switch. Then ran through all the connections you could think of. Finally gave up and lived with it. Could have sworn it was related to bumpy roads and my stiff suspension.

I never did find the culprit. I've since swapped to MS3Pro module ecu and not a single hiccup. Wish you the best of luck finding this damn thing. I know your frustration.

 

Thanks for your input. I don't think it is a bad connection, does not seem to correlate with bumpy roads, or anything like that. I can capture the sync loss, but it is unclear what sensor is not providing the proper signal. I am pretty sure that noise filtering has helped a bit, however it still happens, I got another hiccup this evening on the ride home. Probably will not get a chance to swap crank sensor until this weekend, hoping that might solve it, however I am not feeling to confident about it...

 

My coils caused loss of sync when the car was hot/heatsoaked. Don't know if it was faulty wiring or the unit itself.
I changed to COPS and life was good.

I see you have COPS in your signature. Nevermind...

 

Does it happen with a specific RPS or load? I will get a hiccup at 2800 RPM once in awhile if I am holding steady at that RPM. No issues anywhere else.

 

Unfortunately not. It does usually happen in the 3K area, but I think that is more a factor that I am usually around that RPM. It has happened at idle, and usually the car will stall if it does, however has yet to happen at greater than 4K. And while I do have COPS, I have wondered if I could be getting noise from them, my crank sensor wiring does run parallel to them. I replaced two of the COPs a week or so ago because there were slight cracks in the epoxy covering, but that resulted in no change in behavior.