ms3x lt1 random engine shutdown with time gaps

[242ATL]

Hello megasquirters.

I have a ms3x system in a v3 box powering up an lt1 with optispark and sequential ignition with ls d585 coils (batch fire injection). Running the latest firmware. High impedance stock lt1 injectors.

The car runs great and responds very well to tuning except for what I am calling random engine shutdowns. It doesn't happen all the time, perhaps a frequency of 1 in every 5 drives. I can't get this to happen in my driveway... only when driving. When I say shutdown, I mean it's not stalling, it's literally just shutting off like someone turned off the ignition. (on that note, I went and replaced the ignition switch with a new unit).

I don't typically have any sync errors but once in a while I am getting type 65... not listed in the current manual btw, which stands for "CAS 360 running". The sync errors do not typically occur at the same time as one of the shutdowns.

EDIT... I forgot to mention that this is a basically new optispark unit with maybe 15-20 hours of driving on it.

What I have noticed is that I am getting time gaps... 2.95 second gaps, 3 second, gaps, 6.51 second gaps sprinkled through the log. Every single time I have a shutdown, I will have one of these time gaps immediately preceeding the shutdown. What I found interesting is in two completely separate logs a day apart, I had time gaps of 3.57 seconds immediately before shutdown.

When the engine does shut off, it is extremely difficult to restart the car... almost as if it is flooding. I have to floor the gas pedal to get it to start. The first time it happened I killed the battery trying to restart it. I found through trial and error that if I shut the ignition off immediately after it happened (interesting at 70mph), I could restart it quickly and easily.

I have a datalog posted below where there is a shutdown and you can actually see the time gap where the graphs have a linear downward slope at 3887.415 seconds past 3890.696 then the car shuts off. In fact, if you look at the bottom of tunerstudio it says "Time gap: no log entries for 6.51 seconds". You can then see me shut the car off and floor it to try to restart it.

I have a picture here and the log is below.


I do not have a composite log for this event, but I have included a composite log of driving it around today.

[billr]

I only see that log going to 284.480 seconds...

Okay, a second one just added!

Edit: How about a tune file to go with those logs?

[242ATL]

Sorry... in the process of uploading... working with a really slow Internet connection.

composite log of today's drive just tooling around.

[Matt Cramer]

Are you using a USB or direct serial connection?

[242ATL]

I've used both.

I did some digging into my composite log (had to learn how to read it first) and it looks like my hi-res signal is disappearing.

A normal section


and the next section over


Is this a sign that my optispark is crapping out?

[Matt Cramer]

That looks more like a visualization glitch. If the Optispark is on the fritz, you should see "Lost sync reason" count up at a point when the engine hiccups but stays running.

[242ATL]

one day bump. What would cause an engine to shutdown and leave everything else on... megasquirt, accessories, etc.?


I did some random searching online... apparently random engine shutoffs are very common for optispark cars. The engine turns off like someone flipped a switch.

[Matt Cramer]

Maybe you could tie a LED to VREF so it's on whenever the ECU is on. Then see if it blinks when the ECU shuts down.

[242ATL]

Maybe you could tie a LED to VREF so it's on whenever the ECU is on. Then see if it blinks when the ECU shuts down.

Thanks Matt,

that gives me someplace to start.

So you think the 5v might be crapping out?

regards,

Mike

[Matt Cramer]

This can be caused by a number of things, including loss of power or an external short to ground. However, this is a good quick check to see if the ECU is actually powered up correctly or somehow losing power when this happens.

[jsmcortina]

I did some random searching online... apparently random engine shutoffs are very common for optispark cars. The engine turns off like someone flipped a switch.

For Optispark generally or just with Megasquirt? I've not heard either.

James