Yes, this is a long shot due to UTEC being outdated and no longer as relevant in the Z community.

However, I am using it in conjunction with a turbocharged 2002 Nissan Maxima.

First thing I did was hook up the MAP sensor and load the APS TT 550cc basemap and parameters from the TURBOXS website, since it's optimal to use the MAP sensor and SD mode on a turbocharged car usually. After doing some tuning, out of nowhere the car would go into limp mode purely randomly.

My troubleshooting process:
- restarted car, limp mode went away, continued driving, loaded the engine up to 0vac, continued cruising and again the car went into limp mode without any actual load on the engine. (A/F pegged at 10.0, will not rev past 2,500 RPM).
- flipped UTEC switch to map 0 and restarted. Car ran dead lean. Checked voltage of MAF on UTEC dashboard, it was well below the MAF voltage threshold per FSM. Switched MAF sensors and that resolved this issue.
- random limp mode proceeded to occur when switching back to the base map. Rescaled MAP sensor to read +0.0psi absolute with key ON, this did not change anything. I was a little confused on the wording of absolute vs gauge pressure on the UTEC dashboard but I was unable to get the MAP sensor to rescale to +14.7psi absolute so I just left it.
- switched back to MAF ONLY. Loaded intake & exhaust parameters. Tuned the MAF curve and timing maps to hit appropriate AFR and timing targets with no knock. Loaded the car up several times and let it build full boost without issues, AFR is consistent, loaded it up going up hills, cruised it for about 70 miles without a hiccup. On my way back to the shop, the car went limp again. I also re clocked the charge tube to point the sensor differently.


Everytime I restart the car, limp mode disappears and I can drive it normally.

Based on my findings I feel like this could be a wiring problem but I want to know if there is anything else I need to look at. The harness is a PnP harness made by www.nisformance.com so I highly doubt there could be issues with it. Furthermore, I also switched UTEC units and the problem still remained. The MAF sensor is in a 3" tube to help prevent maxing it out in boost.

Hopefully someone on here has run into this issue before.

Thanks,

 

Monoceff you know me from maxima board bought stuff from you. I know the problem had the same issue myself. My car would go into limp once it hit about 4K rpms. First thing is your min map # should be like 3psi in parameters and Max should be like 3 or 4 psi over the max psi you want to run. That's one thing if not set right can mess you up. The reason I found I was going into limp mode though was I needed to do the relearns. Do the pedal dance like it says on the org for the 5.5 gen. Do all of them and make sure once you do the idle you unhook the battery for like 15 min. I'm sure when you had the car apart you had the battery unhooked for a while plus you changed maf. If you had the upper im off and unplugged tb that can do it too. Try it be sure it sticks and I bet it will stop.

 

Issues covered 3 years ago.ez