G4+ Diagnosing RPM Limit Triggering issue

[craig12895]

Im using the PNP 350z G4+ on a g35 sedan. The sedan has the VQ35DE so the base configuration settings for the 350z ecu should all work well with the sedan. The issue Im having is the RPM Limit falsely being activated causing the car to fuel cut. It would occasionally happen at idle and cruising (does not seem dependent on my particular rpm).

After the fuel cut occurs the ECU statistics would show max RPM being over 13k. In order to not have this interrupt with normal driving I have turned the RMP limit off in the meantime until I could sort out the issue. Trigger filtering is set to 1, which is the default setting for the 350z PNP G4+. And I would attach a trigger scope but it appears that my G4+ does not have that built in, or I at least cannot find the location to access it. I don't have an official oscilloscope handy either which is inconvenient but Im trying to think of other ways to diagnose the issue. I would suspect that incorrect polarity is not an issue as all of the sensors are OEM.

[Adamw]

How to do a trigger scope: https://1drv.ms/v/s!AiYbYlZQuRHPmieMTkwQDCXEb2LY

[craig12895]

Greatly appreciate that link!

And for what its worth, the car acted up about a minute after recording this trigger scope. Max RPM jumped to around 6k RPM and the car stuttered and died, presumably because  its adjusting fuel and ignition as though its at 6k rpm yet I was cruising around 2,000 rpm. 

IdleTriggerScope-craig12895.llg

[Adamw]

Nothing obviously wrong in that trigger scope.  So it potentially could be something that is only intermittent such as a bad connection or failing sensor.

The only bit that is not quite right in your scope is the low voltage on the cam trace sits a bit higher than normal for sometime after the tooth has passed.  Notice in the pic below where the yellow cursor is on the green (cam) trace the voltage not at zero, it is up around 0.8V.  Although 0.8V is fine if it never changes, if it ever did creep up above 1.0V that would cause a problem.  Say if it creeps up with RPM or when there is large electrical loads such as fans running etc...   Notice the crank (blue) trace is more normal at about 0.3V.  

So Im not confident if that is your problem but it is a possibility and something to keep an eye on.  You could try doing a trigger scope at say 5000RPM and see if it looks any different.

If possible it would also be worth swapping the RH inlet cam sensor with the LH (trigger only uses the RH).

Can you also attach a log of a short drive so we can confirm that VVT is not doing anything funny.

[craig12895]

I greatly appreciate that feedback! I have a spare vq35de sitting in the shop and all of the sensors are relatively new (~5k miles) compared to what is in my car. So I will likely just swap the cam sensors with that engine. I won't be able to make progress on this until early this week but I will update when I can.

[craig12895]

Alright so I have attached a trigger scope of the original cam sensors at 4500rpm. Then I swapped the cam sensors and recorded another trigger scope at idle. It seems that I forgot to save the 4500rpm trigger scope with the sensors swapped.

And Ive attached a short log of cruise driving with the sensors swapped. Immediately upon switching the sensors it took the car much longer to start occasionally taking several key cycles before it would actually start and idle on its own. But I started it 3-4 more times throughout the day and it seems to have gotten much better at starting.

ShortCruise_SwappedCamSensors.llg TriggerScope_4500RPM_craig12895.llg TriggerScope_Idle_SwappedCamSensors.llg