R32gtr sputtering and stalling

[thejacksta88]

Hi guys,

I know I lt could be a range of issues although when driving my gtr its starts sputtering and stalling feels like maybe an inter cooler pipe loose or so but that's not the case.

recently had a comp check with 165psi across all 6 give or take a few psi.

a mate was saying maybe IAC valve 

could anyone point me in the direction of where to go from next I was thinking coils / plugs.

 

its due for an upgrade so I'm going to r35 coils. In the mean time I'm Just wanting to get it running alright 

 

cheers 

[Duncan]

when does it run badly; hot/cold/both, idle/part throttle/full throttle

what computer is running it and what data can you get from it?

[GTSBoy]

1 hour ago, thejacksta88 said:

a mate was saying maybe IAC valve

It won't be this - not while it's driving, anyway.

[joshuaho96]

2 hours ago, thejacksta88 said:

Hi guys,

I know I lt could be a range of issues although when driving my gtr its starts sputtering and stalling feels like maybe an inter cooler pipe loose or so but that's not the case.

recently had a comp check with 165psi across all 6 give or take a few psi.

a mate was saying maybe IAC valve 

could anyone point me in the direction of where to go from next I was thinking coils / plugs.

 

its due for an upgrade so I'm going to r35 coils. In the mean time I'm Just wanting to get it running alright 

 

cheers 

What do LTFTs look like? What do MAF voltages look like? O2 sensor voltages/AFRs? Knowing O2 voltages especially when it sputters would help a lot.

[MBS206]

10 minutes ago, joshuaho96 said:

What do LTFTs look like? What do MAF voltages look like? O2 sensor voltages/AFRs? Knowing O2 voltages especially when it sputters would help a lot.

How will O2 sensor voltages help to identify it when it is sputtering?

[joshuaho96]

8 minutes ago, MBS206 said:

How will O2 sensor voltages help to identify it when it is sputtering?

If it's reading full rich prior to a misfire that gives one directional hint, if it's already reading lean, etc. If it's reading pretty cleanly stoichiometric then suddenly drops out from a misfire that suggests it's not air mass estimation that's the problem. Could be ignition, could be something more subtle. Could be the CAS has decided to start dropping out at random or the drive pin is worn leading to excessive lash and trigger errors. LTFT can tell you the same but it's slower to react and if this is a recent issue it might not have stabilized. STFT stuck in one direction vs fluctuating back and forth can be used instead but I like to read O2 voltages anyways and interpret directly.

If the O2 voltages make no sense in general or are super slow to react it could also be a failing O2 sensor. There's no real error correction for failing O2 sensors in these cars.

[MBS206]

37 minutes ago, joshuaho96 said:

If it's reading full rich prior to a misfire that gives one directional hint, if it's already reading lean, etc. If it's reading pretty cleanly stoichiometric then suddenly drops out from a misfire that suggests it's not air mass estimation that's the problem. Could be ignition, could be something more subtle. Could be the CAS has decided to start dropping out at random or the drive pin is worn leading to excessive lash and trigger errors. LTFT can tell you the same but it's slower to react and if this is a recent issue it might not have stabilized. STFT stuck in one direction vs fluctuating back and forth can be used instead but I like to read O2 voltages anyways and interpret directly.

If the O2 voltages make no sense in general or are super slow to react it could also be a failing O2 sensor. There's no real error correction for failing O2 sensors in these cars.

Stock O2 are basically useless beyond anything at stoich.

Any misfire will also be seen as lean.

The stock O2 also read a collective exhaust gas volume, not each cylinder. Sputtering and missing means not each cycle is firing, and some are. Which means even if rich, as shit, on cylinders as they miss, they'll read lean, but the cylinders that did fire will read rich, and combined, well, they can read anything from rich to lean.

 

Start with the basics before even going looking at sensor values.

 

Edit: I say the above, and that's coming from the guy with a few thousand dollars worth of scan tools sitting right beside me right now that I use frequently for my job.

Edited February 7 by MBS206

[silviaz]

3 minutes ago, MBS206 said:

Stock O2 are basically useless beyond anything at stoich.

Any misfire will also be seen as lean.

The stock O2 also read a collective exhaust gas volume, not each cylinder. Sputtering and missing means not each cycle is firing, and some are. Which means even if rich, as shit, on cylinders as they miss, they'll read lean, but the cylinders that did fire will read rich, and combined, well, they can read anything from rich to lean.

 

Start with the basics before even going looking at sensor values.

 

Edit: I say the above, and that's coming from the guy with a few thousand dollars worth of scan tools sitting right beside me right now that I use frequently for my job.

How do you go about diagnosing ecu's that don't have data logging, is it more experience at that point and just trying out things that you think will fix the issue?

[MBS206]

31 minutes ago, silviaz said:

How do you go about diagnosing ecu's that don't have data logging, is it more experience at that point and just trying out things that you think will fix the issue?

Diagnosing with and without is mostly the same. You need to know, as Duncan asked, and what conditions. Car hot, cold, idling, driving, if while driving what rpms, is when you're varying, or is it when held constant.

 

From there it's understanding what can be causing it. Starting with pretending all of the sensors are correct. Which means if it's going rich, why would it be thinking more air is going in than it is, and under what conditions. So things like if only when under boost, it could be be a loose intake piping joint.

It's just understanding the system, and understanding when/how the problem occurs, and then if it's only occuring in specific scenarios, what can be causing it.

 

ECU specifically, if it's aftermarket, it'll have software you can use, for the Skylines on factory ECU, there is Nissan Consult you can use.

Most ECUs have a way to get data from them.

[silviaz]

26 minutes ago, MBS206 said:

Diagnosing with and without is mostly the same. You need to know, as Duncan asked, and what conditions. Car hot, cold, idling, driving, if while driving what rpms, is when you're varying, or is it when held constant.

 

From there it's understanding what can be causing it. Starting with pretending all of the sensors are correct. Which means if it's going rich, why would it be thinking more air is going in than it is, and under what conditions. So things like if only when under boost, it could be be a loose intake piping joint.

It's just understanding the system, and understanding when/how the problem occurs, and then if it's only occuring in specific scenarios, what can be causing it.

 

ECU specifically, if it's aftermarket, it'll have software you can use, for the Skylines on factory ECU, there is Nissan Consult you can use.

Most ECUs have a way to get data from them.

Ah ok, for example for the apexi ecu I heard that it's pretty limited with the information it can give you.

Also not sure why Nissan used the consult port over the obd2, what the idea there was.

Edited February 7 by silviaz

[Duncan]

20 minutes ago, silviaz said:

Ah ok, for example for the apexi ecu I heard that it's pretty limited with the information it can give you.....

Also not sure why Nissan used the consult port over the obd2, what the idea there was.

Actually PowerFC is probably the easiest to get basic data from, it comes with a hand controller and display so you don't need to remember to pack a laptop every time you drive. It also has a PC based viewing/logging option if required.

Nissan used consult on these because back in the mid 80s, ODB was just a glint in a standard's body's eyes.  They switched to OBD shape around 2000 (my 2001 Cima had OBD shaped but not OBD compliant port)

With the standard ECU there is a cable and software available to give basic data too, I think it is called Nissan Data Scan or s

[silviaz]

1 hour ago, Duncan said:

Actually PowerFC is probably the easiest to get basic data from, it comes with a hand controller and display so you don't need to remember to pack a laptop every time you drive. It also has a PC based viewing/logging option if required.

Nissan used consult on these because back in the mid 80s, ODB was just a glint in a standard's body's eyes.  They switched to OBD shape around 2000 (my 2001 Cima had OBD shaped but not OBD compliant port)

With the standard ECU there is a cable and software available to give basic data too, I think it is called Nissan Data Scan or s

Ah ok interesting to know.

[MBS206]

5 hours ago, silviaz said:

Ah ok, for example for the apexi ecu I heard that it's pretty limited with the information it can give you.

Also not sure why Nissan used the consult port over the obd2, what the idea there was.

As Duncan said, first there was OBD, which few cars used, then came OBD2.

 

Now an interesting point, OBD2 isn't even for what you want to do. OBD2 is for emissions testing.

There is some sensor data on OBD2, but it's up to the manufacturer what they're putting on it.

Most scan tools operate on UDS, which like OBD2 is a standard built on-top of CAN.

UDS specifies how to structure a message, what very limited things mean such as "read memory address" but it does not specify what is stored in which memory address, that is all up to the manufacturer. You either a scan tool compatible with that vehicle, or to know how to reverse engineer all the data, which can take a VERY long time and a lot of vehicles to get it right. Oh and then the manufacturer does a firmware update and changes what's where... Ask me how I know that as fact

Oh, and by the time you've got the scan tool that supports all the manufacturers stuff, well, you're back at "But a consult cable and the Nissan software"

The main difference being most manufacturers software these days works with the same hardware readers, as the readers are built to support J2534 which is another standard for how the PC communicates with the tool to make it do specific things on the car...

[thejacksta88]

On 7/2/2025 at 6:05 AM, Duncan said:

when does it run badly; hot/cold/both, idle/part throttle/full throttle

what computer is running it and what data can you get from it?

Hi mate,

 It starts doing this when driving through normal city traffic.

 

Will be when I go to accelerate or if I stop and let it idle sometimes it will shut off.

 

 

[MBS206]

What mods are done to the car?

By driving in traffic, does it die while moving, say at 50kmh? Or its when you're sitting idling it wants to die, or when idling and you go to accelerate?

 

When you're idling, how long is it normally idling for time wise before it starts to miss and sputter?

[r32-25t]

Sounds like an airflow meter 

[joshuaho96]

On 2/6/2025 at 5:24 PM, MBS206 said:

Stock O2 are basically useless beyond anything at stoich.

Any misfire will also be seen as lean.

The stock O2 also read a collective exhaust gas volume, not each cylinder. Sputtering and missing means not each cycle is firing, and some are. Which means even if rich, as shit, on cylinders as they miss, they'll read lean, but the cylinders that did fire will read rich, and combined, well, they can read anything from rich to lean.

 

Start with the basics before even going looking at sensor values.

 

Edit: I say the above, and that's coming from the guy with a few thousand dollars worth of scan tools sitting right beside me right now that I use frequently for my job.

I agree once misfires happen it's basically worthless, but the hope is you can see what's happening in the run up to that. 

[MBS206]

21 minutes ago, joshuaho96 said:

I agree once misfires happen it's basically worthless, but the hope is you can see what's happening in the run up to that. 

Stock O2 sensors are narrowband.

They're useless once you're away from stoich.

IE, useless for what you're trying to do.

10:1 will read the same as 14:1 from the stock O2 sensors. That is, they'll read rich. The same level of rich.

[joshuaho96]

On 2/8/2025 at 12:12 AM, MBS206 said:

Stock O2 sensors are narrowband.

They're useless once you're away from stoich.

IE, useless for what you're trying to do.

10:1 will read the same as 14:1 from the stock O2 sensors. That is, they'll read rich. The same level of rich.

I'm aware, but unless you're actually seeing the voltage the ECU is seeing and you're able to verify the sensors are actually working I find it hard to just trust STFT/LTFT. I will say, logging the ECU comes naturally to me because it's one of the lowest effort methods of diagnosis and I do similar things in my day job all the time. Staring at 20+ charts looking for something that isn't quite right isn't for everyone. NDS1 allows you to log almost everything so that's normally what I do and then sort out the data later. 

[MBS206]

1 minute ago, joshuaho96 said:

I'm aware, but unless you're actually seeing the voltage the ECU is seeing and you're able to verify the sensors are actually working I find it hard to just trust STFT/LTFT. I will say, logging the ECU comes naturally to me because it's one of the lowest effort methods of diagnosis and I do similar things in my day job all the time. Staring at 20+ charts looking for something that isn't quite right isn't for everyone. NDS1 allows you to log almost everything so that's normally what I do and then sort out the data later. 

I agree, don't go trusting those trims. As I said, first step is to put the logger away, and do the basics in diagnosis.

 

I spend plenty of time with data loggers. I also spend plenty of time teaching "technicians" why they need to stop using their data loggers, and learn real diagnostics.

 

The amount of data logs I play with would probably blow most people away. I don't just use it to diagnose. I log raw CAN data too, as a nice chunk of my job is reverse engineering what automotive manufacturers are doing.