Nissan-Navara.net banner

Lazy R51 at speed

22K views 39 replies 5 participants last post by  Propshaft  
#1 ·
Hi, I have a 2011 manual euro 5 non dpf pathy at 75k miles and it's been feeling a bit lethargic of late. Fuel economy hasn't faltered at all. It returns 33mpg over a couple of weeks, and on reset and a casual 50 mile commute with a mix of town/open road I can get 36mpg, which it's always been able to do.

Problems/ symptoms of late have been that throttle response has been a bit dull, and when the turbo picks up (maybe a bit laggy) I can get a good slug of black smoke, similarly at high speed 60+ it really seems to struggle to gain speed. Hills are even worse, it's embarrassingly slow along with a good stream of black smoke.

Apart from that, it starts fine, and drives absolutely fine, no smoke, good turbo pickup and acceleration on the flat/ down hill etc and the good mpg remains.

So far I've done the egr delete, replaced air and fuel filters, reset the ecu. I've checked the turbo and it's a bit oily with a litte play on the shaft. The actuator (electric) also seems to moving through the full rage. Not really suspecting the turbo since it seems to produce good boost at lower speeds, and doesn't burn any oil etc. turbo seems normal for approaching 80k.

With all above done, I seem to have improved throttle response, reduced the black smoke significantly and also removed the injector rattle that it's always had. What remains though is the lack of power on hills and hard acceleration.

Read that the scv can be troublesome, and can the boost pressure sensor, also the fuel rail relief valve.

Also of note when I reset the ecu, the code I got,was 10 slow 10 fast, 10 slow blinksCan't seem to find if this is an error code or not. It might mean no code?

Anyways, I've dumped in a bottle of forte diesel treatment so I'll see how that fairs in the next couple of hundred miles, but was wondering if anyone had any suggestion as to where to focus on?

One other thing to mention is that there's a bit of an oil leak showing from the turbo to IC hose, however I can't feel,see or hear any air leaks from this hose at all.

Any assistance appreciated.

Al.
 
#2 ·
Well, you've done most of the stuff I would have suggested.

Your 10x10x10x10 EML flashes means no faults stored so that is good. :thumbright:

The only stuff left I can think of is;

The small vacuum hoses being loose or split at their ends

The possible loss of boost at the intercooler, the oil staining dioe point toward a slight leak.

If you have an android phone or tablet you could use the Torque app to monitor fuel and boost pressure in real time.
 
#3 ·
Ref the vacuum hose(s). Since it has an electric turbo actuator, I assume this engine doesn't have so many. I did have a look around and there doesn't seem to be any. If there are, then please advise where.

Ref the leak, indeed, there's maybe a tiny leak, but nothing in my mind that would cause a significant loss of pressure, or should I maybe look a bit closer here?

Ref the torque app. Sounds interesting. Do I need a dongle to plug into the car?

Al.
 
#4 ·
#5 ·
#6 ·
Did 100 miles yesterday and on the way back it felt like it was coasting along effortlessly again. Cruised along in 6th Not noticing the hills much at all. Today I felt confident enough to stick the trailer on and pulled 2 tons of sub base home and was pleasantly surprised.

I was under the impression it was well serviced after its second 'free' dealer service. Not so sure I trust these free main dealer services. Best go change the oil too......

Air filter was quite minty and dated early 2013.( I might have done 40 odd k since then) and I doubt the fuel filter had ever been replaced.
 
#7 ·
Car not so great today, if I try and keep up with commuting traffic I just leave blanket of soot. Got the torque app and a dongle. Phone connects to dongle, dongle won't talk to the ecu.

Is there a specific protocol I need to select, since it can't speak with the ecu automatically?
Any assistance appreciated.
 
#10 ·
#12 ·
ok, tried a Samsung S4 also with no success. Tonight on the way home after cleaning the MAF at work, it seemed to be running much better, so gave it a bit of beans up the home straight and the engine light came on and the car went into limp mode. Without Torque operational I went to the local garage who interrogated and found fault code P2478 - exhaust gas temp sensor
 
#13 ·
googling hasn't been very fruitful. Should I just replace said sensor and give it a whirl? conscious that this error could be caused by something else :/

any idea where I can find part no's online?
 
#14 ·
#15 ·
#18 ·
Nissan parts Aberdeen were most helpful. Initially the asked which EGT sensor since there's 5 of them (oh here we go i thought!), but they went and asked some tech's and came back advising that it's always the one on the manifold that goes, 29.50+ vat and will be in stock tommorrow morning. Lets hope it's relatively easy to get to and replace!

Al
 
#20 ·
Got the new sensor. It's located on the exhaust manifold directly behind the turbo exhaust inlet. A pig to get to. Right at the back of the engine and behind the turbo. You've got to remove this blind. The turbo heat shield needs to come off, well not off, just pulled forward enough to get a spanner into the sensor. Still took less than hour.

Decided to compare the two sensors and found the results to pretty much similar between cold , dipped in a mug of boiling water and placed I front of a heat gun on low heat. Ranged from 100kohms cold down to around 950 ohms with the heat gun. Never really more than 100ohm difference between the two.

Installed and went for a test drive, and it was no surprise that after I warmed the engine and found a decent hill that the car went into limp mode after pushing hard on the ascent.

Anyways, I've either picked the wrong sensor and/or it's one of the other 4 that's faulty, or if there's a genuine high gas temp issue being caused by something else.

Posted back my faulty obd dongle, so will have to wait a while until I can do some more testing.

Had the trailer on sunday. Wasn't a huge load , maybe 3/4 ton + trailer. What seems to happen is that I can pull a fair old load up a 10% hill no problem if I'm at low rpm . My problem raises it's head on quicker hills like dual carriageways where there's higher rpm involved.

One thing worrying me, is that I've blanked the egr. Is there any repercussions of doing this on a euro 5? (Conscious that egr system lower cylinder temps) symptoms are the same before and after, but I a never got a enige management light until I blanked the egr?

Al
 
G
#21 ·
best to unblank it and see then if thats the only thing you did to your truck, i bet the code will go away
i had a blank on mine and i didnt see any differance at all, i even think i had worse perfomance, so i unblanked it for my annual test (like Mot) and never bothered with it
the oils are supposed to keep things clean anyway
 
#23 ·
stumpy69 said:
Where in Grampian are you got an obd which I know works which could save the wait if you are close by.
I'm in insch, but commute to aberdeen harbour daily, so any north, north west suburb is easy for me.

Just googled high egt's, and a smokey diesel = high exhaust gas temp. Better take it easy for a bit.

Just to clarify, I can go up a hill and keep the throttle balanced in between tons of smoke and keeping momentum with very very minor acceleration. If I prolong the smoke ( nobody for 2 miles behind) I force limp mode.

I'm getting genuine high egt's in my limited opinion. High egt's can be caused by lots of things. Could have a dodgy injector, could be burned or sticking valves, could even be valve timing, which leads to the question, is the euro5 affected with this timing chain issue?

Al
 
#24 ·
Stelianos said:
best to unblank it and see then if thats the only thing you did to your truck, i bet the code will go away
i had a blank on mine and i didnt see any differance at all, i even think i had worse perfomance, so i unblanked it for my annual test (like Mot) and never bothered with it
the oils are supposed to keep things clean anyway
Not quite as simple as that, the symptoms are the same, but blanking the egr made no improvement. Granted, I've only had a limp mode since blanking, but the car performing much the same. it takes two minutes to remove, so will probably whip it out.
 
#25 ·
I would agree until the actual cause of this episode is tied down that the EGR blank should be removed.

With regards to the blank, there is no guarantee that it will give any kind of performance boost. What it does do, is stop the burnt carbon and oil deposits being drawn back through the intake causing undue wear and tear on the engine internals. The EGR valve itself has been known to fail causing a total breakdown. Some newer models have a exhaust gas sensor fitted on the EGR valve and if a blank is fitted will cause the EML to light and store a fault code, generally without any effect on performance.

I doubt very much if the EGR blank is causing this present problem. It would be brilliant if its removal sorted the problem but I doubt it. :dunno
 
G
#26 ·
in older posts you have said you had the egr replaced under warranty right? did the dealers tell you why the last one failed?
otherwise just remove the blank reset the ecu and see how it goes, the euro 5 reports of the blank had problems mostly when fitting the blank, others have also said you shouldnt since it helps the dpf recycle
anyway gl with the fix