Nissan Navara P1272

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Nissan Navara P1272

Postby RYM6746 » Mon Sep 11, 2017 3:07 pm

Hi All, Here I have a Nissan Navara 2007 chassis no VSKBVND40U0175824 with a fault code P1272 rail pressure control valve signal to low. The vehicle as far as I can see only has one control valve on the HPP. It will clear out until the first WOT. I have scoped rail pressure sensor, control valve voltage and current. I probably should have put another channel on the other wire of the control valve as I am pretty sure both wires come from the ECU. Due to the current reacting as you would expect I think it safe to say that wire is being controlled correctly. And the fault only occurs on a WOT so I would say its a command to pressure feedback issue? In this capture I have added a duty cycle maths channel to possibly help? When the pressure suddenly drops that is it going into limp mode/fault generated and the pedal is still at WOT (I know a channel on the pedal would of helped). Can anyone help with a bit more insight to how that fault code is being generated??
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Nissan_Navara_2007_Diesel_Fuel press reg fault code P1272 BAD.psdata
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Re: Nissan Navara

Postby STC » Mon Sep 11, 2017 9:37 pm

I could send you a similar scope trace from a L200 with P1272 before and after the fix. I had the good fortune to nail that.
First Injector leak off at the point of failure then the same with the blow off. You know how much leak off you should see in that bottle/ those bottles ! WPS may or may not show it on the single return pipe.
You will also know to block that pipe you took off.
If I recall correctly, that is not an easy thing to achieve however you need to do it now or later. No Pain No Gain :D

If the above is cryptic then PM or Call me. Not sure where my help is wanted these days.

Hope that gets it sorted for you.
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Re: Nissan Navara

Postby STC » Mon Sep 11, 2017 9:46 pm

I'm unable to edit my posts or help you in REAL time as my posts have to be moderated and that takes time so:

In addition:
P1272 rail pressure control valve signal to low. - That description I would take with a pinch of salt !!

And the fault only occurs on a WOT so I would say its a command to pressure feedback issue?
Right now I would disagree with that based on that waveform - but please remember I do not have the car in front of me and the one I did have the same problem with in the past was similar but not the same as yours. To many variable out there !
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Re: Nissan Navara

Postby STC » Mon Sep 11, 2017 9:48 pm

Neither can I send or receive PM's

Unfortunately that is that. Shame really !!!
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Re: Nissan Navara P1272

Postby Liteace » Mon Sep 11, 2017 10:40 pm

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Re: Nissan Navara P1272

Postby STC » Mon Sep 11, 2017 10:52 pm

I doubt that a new SCV / IMV / MProp will be that cause of this. It is too violent (the change)!
I stand to be corrected !
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Re: Nissan Navara P1272

Postby STC » Mon Sep 11, 2017 11:27 pm

I could up load the wave forms I have - if you wish ?
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Re: Nissan Navara P1272

Postby Liteace » Tue Sep 12, 2017 10:50 am

STC wrote:I doubt that a new SCV / IMV / MProp will be that cause of this. It is too violent (the change)!
I stand to be corrected !


Here we go again, you know best, i had a spare 5 mins, I had a quick look on the forum with my small screened phone, see the post so i thought I would just highlight another post that's got same vehicle and same fault code and the reason I done it is because it might of helped
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Re: Nissan Navara P1272

Postby Technician » Tue Sep 12, 2017 11:01 am

In my opinion when diagnosing faults on complex systems it is always better to follow the vehicle manufacturer recommendations, as in this case there is a fault code description present, record it check freeze frame data, clear it, run it again and see if the code and freeze frame data return, if so follow that data, if not fault is actually found on that circuit, then look at what other circuits affect the operation of it.

Good advise liteace has provided above.
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Re: Nissan Navara P1272

Postby RYM6746 » Tue Sep 12, 2017 3:02 pm

Thank you all for your help but a new IMV fixed this. I took it on a road test and it started hunting at idle and then cut out. Then with ignition on and engine off it would NOT clear the fault code. I tried 5-6 times. I nursed it back to the workshop and quickly put the scope back on and tried to clear the code again (still wouldn't) and there was no voltage on either wire. I turned ignition off for 10 seconds or so then ignition on with scope attached and I would see a pulse of bias voltage then no voltage again. Left it for 5 minutes (cooled down) then boom fault code cleared and all voltage was restored to both wires. My best guess was the ECU really wasn't happy with resistance through the circuit (its definitely monitoring current flow) and shut it down. Due to the nature of fault as in there was bias voltage present KOEO and the loom wasn't being moved around and originally the fault would only happen on a WOT. I decided it was going to get a IMV so I fitted a genuine one in, adapted it and road tested. No further limp modes or fault codes present. I also got you enthusiasts a good waveform :lol: .

I can say there is roughly around 10% duty difference at 4V of pressure and slight differences here and there but not very conclusive as far as I can see, other than it looks like what you would expect to see. PLEASE feel free to add anything to this if you can spot any conclusive evidence between bad and good
Attachments
Nissan_Navara_2007_Diesel_Fuel press reg and fuel press WOT GOOD.psdata
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Last edited by RYM6746 on Tue Sep 12, 2017 8:23 pm, edited 1 time in total.
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