Nistune Forums

ECU goes to fail-safe mode, but only once engine is fully warmed?


Ok, im having a problem. Not sure when it started, but i believe it was before installing NIStune. I havent been able to drive the car normally for nearly 2 months now.

Anyway, start the car from a dead cold (like sitting overnight or whatever), and it starts and runs GREAT. Once the car is fully warmed up, for some reason it goes into fail-safe mode. It boggs, misses, backfires and RPMs will not get over 2k. The only ECU code present then is the knock sensor, which i am sure is misleading due to the poor running. To verify that it is most likely NOT the knock sensor, i disconnected it, then i copied the normal fuel and timing maps over to the knock fuel and timings maps on NIStune, so that if it were engine knock causing the problem (at extremely light load and good AFRs, doubt it), then when the ECU switched maps to the knock map, it would continue to run normally, since it would be using the same map as normal.

I have checked continuity from the MAF pigtail to the ECU, and verified power and ground at the pigtail. The MAF was working, is it possible it just died? If so, then how come it only acts up when fully warmed up? I am not getting any code for coolant temp sensor, and that remains normal the entire time.

Whats going on? Anyone have any insight? BTW its a N62 Z32 MAF, if it matters.

Thanks,
Jason

what if you disconnect the coolant temp sensor?

so you can still communicate with the ECU when this still happens?

Yeah, coolant temp seems to be accurate. What is FTemp? That one seems to be spiked to max as soon as i start the car. That might be my problem.

And yes, i can communicate with the ECU the entire time. Ive data logged the even, but nothing seems abnormal other than it wont get over 2000RPMs.

On another note, i do seem to get a lot of "Nistune has encountered an unexpected error and needs to close" errors. Not sure why, but it does mess with the datalogging in that it breaks it up each time i have to restart the program.

When are you getting the crash exactly (needs to close message)? I might need a log file to investigate further. Perhaps to do with the logger causing it?

Was just thinking if you remove the coolant temp sensor plug then see if it still happens then? If you think temperature is a trigger of the problem

Okay so the board works fine if you can communicate

If the problem is >= 2000rpms then sounds like your MAF is not working properly. What is your MAF on the car installed? What voltage is it showing as your rev the car?

Perhaps the MAF is dying after a certain engine temperature? Check the reported volts from the MAF once you notice the problem

Which car/engine/ECU part number are we talking here?

I saw a similar weird problem once and it was because we were running the wrong base image in the board. It was an N15 Pulsar and we tried running a U13 base image. It would start fine, then during warmup it would go into limp mode at about 65 degrees. If we turned the car off and let heatsoak take the temp over 70 degrees it ran fine!

We flashed the board with the correct base image and it fixed it.

Story here:

http://www.plmsdevelopments.com/custome ... _n15.shtml

PL

Matt,

Turns out it had nothing at all do with the MAF or the ECU or anything. It was the #3 ignition coil cutting out once the car warmed up. I found it odd that it didnt come off as a dead miss, but rather as bogging down, limited rev, no boost. It was weird that all my Consult gauges looked NORMAL (AFR, MAF, TPS, coolant temp), but it still acted like it did. So i just replaced the coil and its running GREAT again! Now i can finally start tuning it!

I havent yet driven it with the laptop since the new coil got put in, but if it keeps crashing, i will email you some of the datalogs. Hopefully it isnt anything serious.

Thanks for all the help!
Jason

please send them through, since I usually look at those first