Help me diagnose this problem: I can't rev past 3500 RPM intermittently (AK370Z)
 

Hey guys,

So I have been meaning to post this thread about an year and half now. But the issue is SO intermittent, I have been reluctant to do so because when it doesn't happen, I tell myself "the issue has been fixed" ... but it reality it didn't. However, I should say this before I write about the issue first: when the issue doesn't happen, Z runs absolutely 100%. Smooth, fast and actually I think it still feels like it has 15,000 miles! (in reality at 72,xxx). I Autox monthly and once/twice a year HPDE and I have no issue. When this happens, it just happens to randomly. I have Gold prefferred (Bumper to bumper) warranty till 2016 or 120K miles. So I really want this fixed before that expires

Video of the issue: My 370z wont rev past 3500 RPM Intermittently - YouTube




Here's what happens:

Intermittently, my car won't let me rev past 3500 RPM. This started VERY first time (late 2011) after I pulled over on the highway. When I got back into the highway, as I was rowing through gears, it won't let me rev past 3500. Just out of the blue, this issue started. This happens (RANDOMLY) if I accelerate from a stop light or sitting in a traffic jam or whenever. I have no idea when this 3500 rev limiter thing will trigger. It can/has happened 2 minutes into driving the Z, it has happened 2 hours into driving etc. Also, it's VERY VERY random. I can have the rev limit occur on my way to grocery store. Then 2 days can go by and It won't happen, 2 months can go by, it won't happen or heck even 6 months will go by and this will not occur once (I think 6 months was the longest gap). Sometimes it happens twice a day then it may not happen for next 6 months. If this happens, all I have to do is -- Stop the car --> shut the engine off --> open door to reset the car --> I can start the engine and it's fine (for how long, I don't know. It can be 1 hour or 6 months). When it happens, I can still drive the car as long as I row throw the gears and keep it below 3500 RPM. It's when I go PAST 3500, it happens.

I really don't know what's the problem. Has this happen to anyone here? I took the Z for service in past, but they were giving me the :icon08: eyes, thinking I'm crazy. I told the dealer everything but there's NO CODE. They spent hours looking for a code or to replicate the issue -- nope no luck. However they said, if it occurs again, come straight to the dealer. We want to see it. I said,"fine".

Monday 6/18/13 4:20 pm, as I'm going to UPS, this happened again (I think after about 1 month). I went straight to the dealer. Had the tech drive the car and he finally saw what I meant. As I type this, my Z is in the Nissan dealer. All day today they tried replicating the issue first but of course he couldn't get to replicate it as it's VERY random (and even I have no idea what triggers it). Tech called Nissan Tech line and they were confused as well. They (NIssan) first suggested a faulty oil temp sensor which is telling ecu the oil temp is high (but in reality it isn't). I personally think it might be a buggy old ECU as my car is one of the earliest built car. Tech wants to call Nissan tech tomm or try to replicate the issue again so that there's a solution to this (and I told them I really want this fixed as I bought the car before for exact thing). i have done overnight negative battery terminal reset in past and it doesn't fix it. I have tried that.

What do you guys think is the issue? Has this happened to anyone? What should I tell the tech tomm to look specifically? You help, comment, suggestion is highly appreciated. :tup:

Are you UpRev tuned at all in a way you could drive around and do a Data Log to try and see what happens when this happens?

No tuned at all. Bone stock. That did came to mind but I rather want dealer to fix it under warranty as plan A.

Loose connector, bad sensor, or bad computer (more like bad/corrupt update). Check your battery cables make sure they're tight too. I had a similar issue with my old car. I had a red top optima and the side post bolt was stripped. I had random performance issues just like this, changed the post and it was fine. Took 6 dealer trips, 2 alternators, and one trip to something like pepboys to figure it out.

I understand that of course, but it might be time for you to look into a tune... 72k on Stock tune with bolt ons, is pretty far.

Wondering if maybe an o2 sensor or something has been clogged over, and the ECU is holding back to compensate?


Quick google search brought up these threads... one might have promise:

http://www.the370z.com/engine-drivet...all-gears.html

http://www.the370z.com/engine-drivet...pm-help-2.html

Specifically, this post:


http://www.the370z.com/nissan-370z-g...tml#post250296

:ugh2:

Not to be completely off topic, but do you go to the dealership and say, "hey... So, the world's largest 370Z forum... Yeah, the370Z.com, I OWN that bítch, fix my car or I will own you too!"

Lol :icon18:

This may be completely unrelated but this happened to me at the track during my first event and one of the threads on the forum said to disconnect the battery, drain all the power by holding down the brakes, and reconnect and it should be fine. It fixed it for me and it hasn't come back since no matter how hard I drive.

Then again after a year my car only has about 7k miles on it. You might try that to see if it makes your problem go away. Ofcourse, the way you describe it, you may not know if it's fixed for a good 6mos.

The dealer is prolly like:



:bowrofl:

I LIKE IT. :excited:

Check all the sensors and wire connections, and if they all look okay, then maybe have them do an ECU flash?

Hardware is fine judging from you being able to drive normally 99% of the time, so I'd chalk it up to something clogging the sensor (and vibration / rattle re-clogging it), a loose connection somewhere in the wiring harness, or the software has gone weird.

Very hard to diagnose on their behalf with no error code to guide them for starters.

I'm with the thinking it's a technically glitch, And with a simple reset/restart it usually goes away.

I would figure it's something to do with either oil temp sensor telling the ecu go into limp mode or the ecu maybe causing the issue.

Sorry to hear she's spending the night at the dealers, But IF they can replicate it?

They should figure it out. :keepingfingerscrossed:

mine did this too. was an auto 7 speed and would only rev to 5k. had no other issues while driving just when revving would top out at 5k. very strange

When I had that issue we traced it back to a faulty crankshaft position sensor

I had something similar like that happen on my Altima Coupe 3.5 6MT, but when it happened it was a weird stall that I had in a parking lot due to some moron in front of me (and a brain fart on my part). When I stalled, I restarted kinda quickly as traffic started moving again and when I clutched in, the VDC and SLIP lights came on, and I couldn't rev past 2500 rpm (it would bounce fairly violently at that RPM).

I pulled over into the next parking lot, turned off the car, waited 30 secs, started it up and the lights were gone and I never had it happen again until I traded the car (20,000 or so additional miles over a year's time.)

Your issue is peculiar as you have no trouble codes or anything. The crank position sensor is likely not it as it should throw a code.

My instinct say it's something to do with the oil temp sensor as, to my knowledge, it is the only thing that can throw a car into a "limp" mode without throwing a trouble code. A Nissan CONSULTIII tool should be able to pull the information on the temp sensor as I believe it is logged when you ping the 260 degree limit, but will not throw a code.

I would take it in and at least have them look at it. You paid for the warranty.