MS ver 2.890 datalog problem

[Martin Wagner]

I have a miata that has been running on a microsquirt since the fall of 2007. This spring I installed version 2.890. Since that time I have had a number of problems with the engine shutting off at high rpm for no know reason. Last week I went to the dyno to see if I could determine any problems. When I looked at the datalog files, there is NO data above about 5000 rpm. The attached 3 log files were made using megatune v2.25. Run1 at time 383.752 (secl 230) shows rpm 4929 and tps 104. The next entry is at time 396.990 (secl 243) with rpm down to 4871 and tps 0. The run was made to about 8000 rpm with no issues. Any idea where the 13 seconds of log data might have gone? Run3 shows the same type issue at time 1347.186 (secl 345) with the next entry at time 1363.137 (secl 361). Run2 should have shown a high rpm shutoff since the engine died at 7500 rpm. The datalog stopped at 976.098 (secl 445) with rpm at 5133 and didn't restart until the ms was powered off and back on at time 1002.290. Last year I made several datalogs using the same version of megatune but a different ms version (v2.883j I think) and had no problems with missing data.

[grippo]

If you think it is a code issue, try reloading the old code. I know Bruce has run the 2.890 code to 13000 rpm with no problems, so I don't think it is a cpu speed problem. As for the datalog, I'm not sure what is going on there. The throttle was lifted right after it happened, so I am assuming you felt something wrong with the engine, but there doesn't seem to be anything that affected the cpu - it didn't lose synch or miss any tach pulses. If you have a stim you can try running on that and see what that does at high rpm.

[Martin Wagner]

Runs 1 and 3 were normal dyno runs. I start the car, run up through the gears at moderate rpm. Once in 4th gear at 3500-4000 rpm, I signal the dyno man and my brother who start the dyno log and megatune datalog and I run the engine up to 8000 rpm. I then lift off the throttle while shifting into neutral. When the engine gets back to (or near) idle, I shut off the engine and microsquirt. The resets near the end of the datalogs are when I turned the ms off and back on. The logs show the engine going up to 4-5000 rpm under load and coasting down after the run. The time the car was spinning the dyno up from 4-5000 to 8000 doesn't show up in the datalog. The Megatune tach gauge stopped at 4-5000 rpm but the tach in the car (run from ms tachout) ran up to 8000 rpm. Run 2 was abnormal in that the engine shut off at 7500. On that run the datalog doesn't show a coast down, the datalog doesn't restart until the ms is power cycled. That is the failure we have on the track. The engine shuts off and won't restart until the ms is power cycled. It does restart if I power cycle the ms while the engine is still turning over.

I will try an older version to see if it corrects the datalog issue. I'll try 2.886 and if it still fails I'll try 2.883j.

PS I just looked through my recycle bin and found 3 datalogs from dyno runs in March. They were made with 2.890 and logged up to 8150 with no lost data. Looks like the lost data is some sort of hardware problem.