Overboost limp mode?

[FSUZ33]

Even with things going wrong, could the turbos spool to 23 psi THAT fast? I feel like this is an electrical/sensor thing.

In the first video:
4,800 RPM, 40% throttle, 0 psi
-> 100% throttle
0.7 sec later, 5,200 RPM & 23 psi

In the second, "less aggressive" video:
4,000 RPM, 25% throttle, slight vacuum (-1 or -2 psi)
-> 100% throttle
1.2 sec's later, 5000 RPM and 23 psi.

I could be wrong, but 23 psi in 3/4 of a second and a 400 RPM swing seems physically impossible on stock turbos and stock exhaust.

 

[AugustusCaesar]

Even with things going wrong, could the turbos spool to 23 psi THAT fast? I feel like this is an electrical/sensor thing.

In the first video:
4,800 RPM, 40% throttle, 0 psi
-> 100% throttle
0.7 sec later, 5,200 RPM & 23 psi

In the second, "less aggressive" video:
4,000 RPM, 25% throttle, slight vacuum (-1 or -2 psi)
-> 100% throttle
1.2 sec's later, 5000 RPM and 23 psi.

I could be wrong, but 23 psi in 3/4 of a second and a 400 RPM swing seems physically impossible on stock turbos and stock exhaust.

So you're thinking electrical? Would there be a fuel cut on a false boost reading? If the gauge reads 20-23psi would it initiate a failsafe even if its not making that much boost?

The dealer I bought my car from is 5.5 hours away from me. And the closest dealer (both Nissan) is about 3 hours away.

 

[FSUZ33]

Completely throwing a dart while blindfolded, but maybe it's going into limp because of the boost pressure (or perceived boost pressure) and it's trying to avoid a lean condition.

 

[offizial]

Completely throwing a dart while blindfolded, but maybe it's going into limp because of the boost pressure (or perceived boost pressure) and it's trying to avoid a lean condition.

So the Z can take 20-21 psi and be okay in the case of Tuning and tuner boxes. So I’d say that yes, that there’s an issue with the pressure gauge because the car reads what the gauge is saying, then notices the A/F ratio does not signify that specific ratio where the boost pressure gauge is saying and what it’s actually making therefore it enters limp mode. But you also say that you feel a slight performance boost so maybe it is actually making that boost. So it would have to be an issue somewhere mechanical. Turbos, intake, fuel pump. It’s hard for us to guess, but unfortunately in that case it would be hard for the dealership as well. Imo, from the sound of the car and speed you are accelerating, it seems close to stock. But it’s NOT the gauge itself as it’s showing electronically. It could be this: TMAP sensor on top of each intercooler. Try one, replace one, if the issue is still occurring, switch sides. Then you know it can’t be that at least.

 

[AugustusCaesar]

So the Z can take 20-21 psi and be okay in the case of Tuning and tuner boxes. So I’d say that yes, that there’s an issue with the pressure gauge because the car reads what the gauge is saying, then notices the A/F ratio does not signify that specific ratio where the boost pressure gauge is saying and what it’s actually making therefore it enters limp mode. But you also say that you feel a slight performance boost so maybe it is actually making that boost. So it would have to be an issue somewhere mechanical. Turbos, intake, fuel pump. It’s hard for us to guess, but unfortunately in that case it would be hard for the dealership as well. Imo, from the sound of the car and speed you are accelerating, it seems close to stock. But it’s NOT the gauge itself as it’s showing electronically. It could be this: TMAP sensor on top of each intercooler. Try one, replace one, if the issue is still occurring, switch sides. Then you know it can’t be that at least.

I'll take it to the dealer then, I'm in Canada, so that price is much, much higher than the site says. And also, on a brand new car that only JUST hit 3,000 km on the odometer, the dealership needs to be paying for everything.

I appreciate all your help!

 

[FSUZ33]

A trip to the dealer is the best. Sucks they’re so far away though. Keep an eye on your temps and pressures. Not that you’ll have a problem, but best to play it safe. I’d bet a dollar (USD ) that your issue is NOT anything I have suggested.

Good luck! Look forward to hearing the diagnosis.

 

[AugustusCaesar]

A trip to the dealer is the best. Sucks they’re so far away though. Keep an eye on your temps and pressures. Not that you’ll have a problem, but best to play it safe. I’d bet a dollar (USD ) that your issue is NOT anything I have suggested.

Good luck! Look forward to hearing the diagnosis.

Wait wait wait.
You bet a USD my issue isn't anything you suggested? So you bet it's none of the above? ?

 

[FSUZ33]

I try to help, and I know a little bit about stuff, but wallow in self-doubt.
Nothing against you, just preparing myself to be wrong.

Will $0.50 CAD make it better?

I’m hoping it’s mechanical and whatever it is can be replaced. If electrical, hopefully that’s a quick fix too. Chased electrical gremlins on my wife’s old car, and…well…let’s just say, fortunately you’re covered under warranty. We ended up donating it to Goodwill just to get rid of it.

 

[AugustusCaesar]

I try to help, and I know a little bit about stuff, but wallow in self-doubt.
Nothing against you, just preparing myself to be wrong.

Will $0.50 CAD make it better?

I’m hoping it’s mechanical and whatever it is can be replaced. If electrical, hopefully that’s a quick fix too. Chased electrical gremlins on my wife’s old car, and…well…let’s just say, fortunately you’re covered under warranty. We ended up donating it to Goodwill just to get rid of it.

UPDATE!

Dealership has no clue what the heck it is.
That's coming from a 25 year Nissan Master tech. Who checked evrything physically, and then did live data logging with me while I drove, trying to replicate the issue.

He has to open a ticket with Nissan Japan to consult on the issue, and then he'll get back to me. In the meantime, he reset the wastegate actuator position.

 

[ZMidlife]

UPDATE!

Dealership has no clue what the heck it is.
That's coming from a 25 year Nissan Master tech. Who checked evrything physically, and then did live data logging with me while I drove, trying to replicate the issue.

He has to open a ticket with Nissan Japan to consult on the issue, and then he'll get back to me. In the meantime, he reset the wastegate actuator position.

A good friend is a nissan engineer, ill ping him and see what he thinks

 

[ZMidlife]

OP PM me. Buddy has some questions

 

[AlfredoGonzalez]

Hey guys, I'm having a weird issue. I need some help.
I have a 2024 Nissan Z with 2,900 km on it.
Stock, aside from a muffler delete.

Car has run amazingly up until now.
I have no codes, no DTCs, no discernible leaks.

The car seems to be building boost too quickly, and too much or something. I'm hitting 20psi of boost at like 4,700 rpm I'm third gear. And then I get an insanely aggressive power cut that jerks the entire car immensly. I don't know if it's spooling too quick, and there is an overboost failsafe that kicks in? But I try to do a pull and each time I'm getting this aggressive, lurching, power cut. And each time, I think I'm hitting 20psi of boost.

I don't know what in the heck!
And I want to try to see if someone has had this issue and if I can fix it without having to go to the dealer.

Any update??

 

[AugustusCaesar]

None.
Unfortunately no resolution so far.

Any update??

 

[AugustusCaesar]

UPDATE!
Dealership spent 5 hours with the car, checked out the TB plate.

Tech concluded there is NOTHING wrong with the car mechanically.

We continued to log, and it shows the throttle closing at the same time the issue occurs. Not the wastegate, but the throttle plate in the TB.

Tech thinks it's a software issue.

Waiting on further info from engineers.

 

[VR30Infection]

UPDATE!
Dealership spent 5 hours with the car, checked out the TB plate.

Tech concluded there is NOTHING wrong with the car mechanically.

We continued to log, and it shows the throttle closing at the same time the issue occurs. Not the wastegate, but the throttle plate in the TB.

Tech thinks it's a software issue.

Waiting on further info from engineers.

Wow, so they think the throttle plates could be closing even though you are full steam ahead?