D22 YD25 limp mode, pressure relief valve

[jrammy]

Hi,

First time poster, read lots of threads and the forum has been very helpful!

Purchased a 2014 D22 YD25 Nav 9 months ago. 150k kms. Great condition exterior and interior. Drove well.
With me it's had a service, new fuel filter, new air filter. New SCV (more below).
I've had a king brown 3"dump pipe fitted and a custom exhaust fabricated since owning it (100 cell cat, small resonator)

I noticed after owning for a few months it sometimes hit a limp mode on revving it out or taking off quickly. I decided to change the SCV with a genuine one, which helped. I actually thought the problem was fully fixed for a while. It was also noticed to run on 3 cylinders when cold only and after some diagnosing a single fuel injector was changed, took a chance on just changing one as the ECU was maxing out the fuel trim on this injector. This smoothed things out and it ran and continues to run really well. The garage (well respected diesel setup) thought that my Nav might have had a remap as they both felt it pulled very well. I've never found any evidence of this, no chip etc.

Current symptoms I'm hoping to resolve:
Occasional limp mode
Noticed when revving it out in second gear
Hit around 3800rpm and the power sometimes drops, feels like it runs at less than full power. It doesn't appear like a full limp mode, but restarting the engine will fully resolve the issue.
(I only occasionally push the truck this far)

I've read that the fuel pressure relief valve in the fuel rail can be problematic (noting I've already changed the SCV). Would this fit my symptoms? If it opens prematurely, would it reduce engine power until a restart? Or would it be expected to close again when the throttle is off?

I am going to try and find a way to access my fuel rail pressures values, which might provide narrow things down.


Cheers

 

[Old.Tony]

The 2014 D22 should be using standard OBD2 codes, so a Bluetooth OBD ELM327 adapter and an app like Torque for Android will give you the data you're seeking.

Apart from overboosting (which happened on mine, when the input hose to my Tillix valve developed a leak and allowed the turbo to boost as much as it wanted) I can't think of much else that would do what you're seeing.

An ECU edit doesn't require an external chip. The easiest way to tell (without any input from the previous owner) is to back up the ECU, flash a default factory program to it and see if it's any different.

There's a chance that if the ECU was edited (and particularly if done by someone who may have not accounted for all conditions) that certain extremes could cause the ECU to chuck itself into failsafe mode.

 

[jrammy]

Hi Old Tony

Cheers for your reply. Yeah, I can't think of anything else logical although I'm quite new to diesels. The only other symptom is once the power drops at high revs, there's increased smoke until the egnine restart, which I think makes sense with worse atomisation of diesel at the injectors due to decreased pressure.

I think I'll take the chance on a new valve and see what happens.

I'll look to get the fuel pressure data soon too.

 

[Old.Tony]

Have a squiz at a couple more things before you throw money at it. If it's blowing black smoke there could be a couple of possibilities there:

1) Excess fuel due to injector open for too long or excessive fuel rail pressure
2) Insufficient air from turbocharger because turbo is stalling or intake pipe collapsing
3) EGR valve opening inappropriately which reduces available oxygen

I'd try monitoring the boost levels and see if the EGR can't be blocked to test this out. These are cheap to do!

 

[Matt Lowden]

Hi,

First time poster, read lots of threads and the forum has been very helpful!

Purchased a 2014 D22 YD25 Nav 9 months ago. 150k kms. Great condition exterior and interior. Drove well.
With me it's had a service, new fuel filter, new air filter. New SCV (more below).
I've had a king brown 3"dump pipe fitted and a custom exhaust fabricated since owning it (100 cell cat, small resonator)

I noticed after owning for a few months it sometimes hit a limp mode on revving it out or taking off quickly. I decided to change the SCV with a genuine one, which helped. I actually thought the problem was fully fixed for a while. It was also noticed to run on 3 cylinders when cold only and after some diagnosing a single fuel injector was changed, took a chance on just changing one as the ECU was maxing out the fuel trim on this injector. This smoothed things out and it ran and continues to run really well. The garage (well respected diesel setup) thought that my Nav might have had a remap as they both felt it pulled very well. I've never found any evidence of this, no chip etc.

Current symptoms I'm hoping to resolve:
Occasional limp mode
Noticed when revving it out in second gear
Hit around 3800rpm and the power sometimes drops, feels like it runs at less than full power. It doesn't appear like a full limp mode, but restarting the engine will fully resolve the issue.
(I only occasionally push the truck this far)

I've read that the fuel pressure relief valve in the fuel rail can be problematic (noting I've already changed the SCV). Would this fit my symptoms? If it opens prematurely, would it reduce engine power until a restart? Or would it be expected to close again when the throttle is off?

I am going to try and find a way to access my fuel rail pressures values, which might provide narrow things down.


Cheers

Hi mine was doing the same thing very frustrating put it into a good diesel mechanic my way and the hooked it up to diagnostic machine ( if thats what its called ) and said the scv and the fuel pressure regulator have to be changed. they did itr and the problem was fixed he said when you change the SCV you change the fuel pressure regulator because they work together

 

[jrammy]

Hi Matt,

thanks for replying. I thought the SCV acted as the fuel pressure regulator? It might just be different terminology used. Do you know exactly which part was changed?

 

[jrammy]

Have a squiz at a couple more things before you throw money at it. If it's blowing black smoke there could be a couple of possibilities there:

1) Excess fuel due to injector open for too long or excessive fuel rail pressure
2) Insufficient air from turbocharger because turbo is stalling or intake pipe collapsing
3) EGR valve opening inappropriately which reduces available oxygen

I'd try monitoring the boost levels and see if the EGR can't be blocked to test this out. These are cheap to do!

The EGR is blocked and has been soon after I purchased it.
I think it would be interesting to check the boost level, I think I'd need a temp gauge and to T piece it in to gain that info. Would certainly help narrow down

Cheers

 

[Matt Lowden]

Hi mine was doing the same thing very frustrating put it into a good diesel mechanic my way and the hooked it up to diagnostic machine ( if thats what its called ) and said the scv and the fuel pressure regulator have to be changed. they did itr and the problem was fixed he said when you change the SCV you change the fuel pressure regulator because they work together

GENUINE SCV
PRESSURE RELIEF VALVE GENUINE
FUEL FILTER
https://navarapart.com.au/product/f...ve-suit-nissan-navara-d40-pathfinder-r51-yd25the pressure relief valve is like a bolt with a filter that goes in the end of the fuel rail which works together with the scv the mechanic said dirty diesel can cause the issue which those parts then need replacing Hope this helps

 

[jrammy]

Thanks mate.

I've just scanned it for codes, has one logged P0093 which is "fuel leak" and a common cause seems to be pressure relief valve opening.

I think this is enough for me to order one and get it fitted.

I'll update the thread

 

[Marked]

GENUINE SCV
PRESSURE RELIEF VALVE GENUINE
FUEL FILTER
https://navarapart.com.au/product/f...ve-suit-nissan-navara-d40-pathfinder-r51-yd25the pressure relief valve is like a bolt with a filter that goes in the end of the fuel rail which works together with the scv the mechanic said dirty diesel can cause the issue which those parts then need replacing Hope this helps

Pressure relief valve is a "ball" and spring mechanical setup ... crud stuckbin it would likely give you issues at all time, not just at high revs, as they operate under considerable pressure - a slow leak through the PRV while running is likely to trigger a P0093 mass fuel leak error code. Going on my daughter's experiences, limp mode is pretty much complete loss of boost, and there is no "limp mode lite" version.

 

[Aaron31]

https://www.aliexpress.com/item/328...o.order_list.order_list_main.5.2fcb1802FQmyTM
It is as exactly as pictured - same as the apparent genuine (Isuzu) part as shown on Patrolapart.. I know, because I got one. Along with an airflow sensor - which is excactly the same as the stock one (down to the way its numbered). Do identical looking units make them same OEM quality? Who knows... Have I kept the old units, yes.

 

[Marked]

https://www.aliexpress.com/item/328...o.order_list.order_list_main.5.2fcb1802FQmyTM
It is as exactly as pictured - same as the apparent genuine (Isuzu) part as shown on Patrolapart.. I know, because I got one. Along with an airflow sensor - which is excactly the same as the stock one (down to the way its numbered). Do identical looking units make them same OEM quality? Who knows... Have I kept the old units, yes.

Patrolapart charges a premium on everything they stock. Definitely look on e-buy if you want the "genuine" isuzu part at a fraction of the patrolapart price.

 

[jrammy]

Update, to close the loop. New fuel rail pressure relief valve fitted and the issue seems to be resolved. It's driving really nicely.

 

[Marked]

Update, to close the loop. New fuel rail pressure relief valve fitted and the issue seems to be resolved. It's driving really nicely.

Still chasing the daughter's intermittent limp mode. I'm at replacing fuel lines and hose clamps in case a slow leak in the low-pressure section is letting air in. Considering fuel pump. She got sick of it and replaced the d40 with an np300, so I need to sort it to sell it and get it out of my yard. Yippee. Am also considering that she was just running the long range tank too low on fuel too often as well.