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Thread: Weird ECU loss of function.....

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2013-05-29 20:02:08
Weird ECU loss of function.....
Car: 92 SE-R, VE, DE MAF, VE injectors, NEMU RT ECU (modified rom).

This is a dedicated track car for road course racing. Fully gutted and caged. The car was dyno tuned, but after ~90 minutes of running the car enters a type of "limp mode". It isn't the normal limp mode when the MAF is dead since the car will barely rev to 6k rpm. Testing sessions of 20-40 minute sessions don't cause the issue to be triggered. After the car gets weird, you can re-flash the ECU with the same program/rom; and the car runs correctly......for 15 minutes and the cycle starts over. The ECU has been sent back to JK Tuning once, and it was thought to be a dead back-up battery. To be safe, a 2nd RT ECU has purchased; and this one will act the same way.

The car was a stock DE all around last year. VE was installed over the winter with a spare DE harness purchased from the forum, so I'm not convinced it isn't harness related since I can't guarantee the harness doesn't have some goofy short. Another odd occurrence was the igniter (the little credit card sized sensor) died before the last race. I've personally not had one fail on any of my street cars. Granted this one is 20+ years old with who knows how many miles.

We are leaning towards installing the original wiring harness to eliminate that as a possible area. Two identical NEMU ECUs acting the same way is weird. I do not know if the ECU is "losing" the rom or is something else causing the error? I do not believe the CEL is showing when this happens (but I just thought of that). It is possible the memory is getting cleared during the re-flash which allows it to run fine for 10 minutes before the issues start again.

Any ideas?


PS: I'm going to try and run the RT ECU in a local B13 to see if that car exhibits the same symptoms after 90+ minutes of driving. The problem is that this car will be driven on the street not the race environment.
2013-05-30 00:15:40
Swap the harness out. Seems to be the most likely candidate.
2013-05-30 18:39:13
You need to see what the ecu codes are if any. some codes will not trip a mil light but can been seen when viewing the ecu live. check your grounds before swapping the harness. Igniters do go bad but it does not happen that often.
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