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 2 hours ago 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 1 hour ago 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