I have a friends 2001 Maxima that won't rev above 4 or 5K. It also is not displaying a CEL either. I have searched around on the forums, and I noticed a lot of these indications meaning a bad MAF. I find this strange because there is no CEL illuminated, and I'm getting a good signal from the MAF, TPS, Coolant and Air Temp sensors with my scanner. Is this something that any of you guys have seen? I usually just work on vehicles with H's or A's on the hoods, (let the hate begin) so I don't have a lot of experience with Nissans. Any help would be great. My friend doesn't want to sell this car he just got cause it runs like sh*t. It only has 40K and seems like a good car, other than the running issue.

What are you using for your good reference for MAF signal?If it helps, page 155 here shows the testing procedure and proper voltages.

Does it run rough at all or just top out at 4k?

A bad MAF won't always trip the CEL, so the absence of a CEL doesn't necessarily rule out the MAF as your culprit.

It just stops reving. Not really running rough; more like it has hit a rev limit. I haven't checked the actual voltage output, but I have viewed the MASS AIRFLOW output on the last line of the chart. It was in specification. I don't have access to a CONSULT II scanner, and I am making do with my generic AutoEnginuity OBD2 scanner (I only have the ChryCo OEM module). I'm going to try a can of CRC Mass Air Sensor cleaner tonight and will report on results. Any other troubleshooting hints?

CRC Mass Air Sensor cleaner did the trick. As soon as I pulled the sensor out, the wire was visibly dirty or corroded. Sprayed the wire, and it was obviously much cleaner. The wire was nice and shiny. Popped the sensor back in, plugged it up, and wow, what a difference. Car runs great. Good acceleration, nice engine sound, lots of power. Thanks for the help. If I ever have to work on any other Nismo stuff I'll definitely stop back by. Good forum with lots of info!!! Would have never tried that stuff otherwise.

Glad to hear it!