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Discussion Starter · #1 ·
Hi Guys,

I have had my navara diagnosed for black smoke and weak performance.

Nissan found the scv to fluxuate from 26 to 34 mpa (should be 40 mpa) They advised to:
Replace scv which i have done without sucess
Check fuel pump timing as the car "runs on" when you turn the ignition off.

When I went to check the fuel pump timing I found there is two slots where the 6mm locking pin fits into the pump? see photos.

Is it possible that the previous owner have had the timing set and used the wrong pin hole resulting in the pump being set one cog off?

Is there a other way to check that the pump is set correclty? or is the only way to pull the pump out and reinstall?

Cheers
 

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Discussion Starter · #3 ·
No unfortunatley I did not do the reset... bad mistake..
Ill check the throttle, i acutally never noticed it running-on but nissan noted that..
Alright, ill put everything back togheter and hope for the reset of the scv being the issue.

When you say not run properly with injector pump one cog out, it wouldnt hold idle and stall etc?

The car starts right away and is sort of driveable, it just feels a bit sluggish and blows a bit of smoke (not too much, seen way worse)
 

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Discussion Starter · #6 ·
Alright seems strange to me that Nissan would advise on wrong injection timing reading the above. Also seems strange that there is no need to time the injection pump when there is a locking pin on the injection pump? But YD25.com.au said the same thing as you - no need to time the injection pump)
My theory was that cam and crank is set correctly but the injection is off.
How would disconnecting cam and crank destroy my engine? Fuel injection would potentially happen at the wrong time without cam/crank read?

Not sure when or if the chain has been replaced or checked. I’ll buy the tools required to check the chain, I guess this is a overall good thing to do every time you take the chain cover off.
 

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Discussion Starter · #8 ·
Tried restetting the scv/fuel pump through the pedal procedure, no stored codes and no success.
Checked my cam/crank timing and it also looks good.
When disconnecting the camshaft sensor there is no smoke, however there is also no boost. Same goes for the Maf sensor.
Intake flap operates as it should.

It only seems to smoke under load (uphill) or at high revs/boost. I feel like Im left with either a faulty injector pump or bad injectors.

When Nissan found the scv to fluxuate from 26 to 34 mpa does this mean that the injectors does not get enough pressure?

Some kind of sickness that YD25s run rich after getting a lot of kilometers? Litterly every second navara I see have this kind of behaviour to some degree...? Tuning?
 

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Discussion Starter · #9 ·
To add to this further, this car has been overheating and I have replaced the cylinder head and head gasket.
In this video he explains that the oil sweep ring can become contaminated so the freeze from overheating/not chaning oil.

I havent followed the oil stick enough to see if its actually taking oil or if its overfueling.

Just pulling all strings I can to get to the bottom of this fault.
 

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Discussion Starter · #15 ·
More things that can go wrong now compared to then I guess..

I can see how the injectors would not like the heat.. I have been struggling to get glow plugs out from overheated engines, never reflected over the injectors. I guess if I’m lucky it’s just the injector nozzles and she’ll be right. Or is it likely other parts of the injector is damaged?
 

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Discussion Starter · #18 ·
I normally just bypass the fuel filter when troubleshooting, but not sure if that’s the right way of doing it?
As you are saying premium diesel and additives are very cheap I’ll give it a go as I’m waiting on getting the injectors looked at.

another thing I have noticed is that after replacing the scv the car has started to struggle to hold idle, it’s not a lot but enough to notice if you listen close enough.

I wish I had a scanner that could read engine load and injector readings like injector compensation. I have a few Navaras with this issue, in fact pretty much all of them blows smoke to some degree.

I have another thread about this and it sounds like Nissan consult is the only way to go.
 

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Discussion Starter · #19 ·
Read on another thread that the Autel AP200 can do injector coding on Navaras so Ill give this one a crack hoping it can show live data on the injectors as well. Fingers crossed
 

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Discussion Starter · #21 ·
Not sure tbh, havent played around with pumps much in the past.
Thanks for the advice will give it a go. Seems fairly easy to do.

Im not getting a great deal of smoke, its just enough for it to be annoying. And its seems to be lacking power on low revs, ie when you take off letting the clutch up. But when the turbo kicks in it runs pretty good.

Ill do a compression test as well. Had some rusty gunk in the cylinder walls when I pulled the head off. Perhaps this could be compression related.

Ill also double check the valve clearance as I did not check it. Trusted the supplier to have it set correctly from factory. Maybe the inlet valves are not opening correctly.
 

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Discussion Starter · #22 ·
Clean fuel coming out
Comp test was 21-22 on all cylinders. Probably a bit more as my test nipple did not get a snug fit on the cylinder head
Valve clearance looks good

Had a chat to a chap at a fuel injector place and he said 9/10 injectors will come back faulty as the are only meant to last 100.000kms. He basically said its better to just replace the then to have them tested..

Ill wait until I can read my injector compensation before getting new injectors. Hopefully I can get away with just replacing a few. If compensation is looking good im guessing im up for a new pump.

I could probably pull out a set of a injectors out of a good running yd25 and see if that makes a difference as well before biting the bullet.
 

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Discussion Starter · #28 ·
Injector pump made no difference either..

Apart from the fuel rail, hoses and pipes. I think I have replaced the whole diesel system now..

its still kind of sluggish on low revs and leaves a bit off a puff of black perhaps gray smoke over 3000rpm

I am starting to fear that this is just the way the Navaras are went they get over 200.000kms or that this issue is related to bottom end

if anyone wants to throw some more suggestions please do so..

Air filter
Maf sensor
Scv valve
Fuel filter
Injectors
Injector pump
Boost leaks
Egr blank at the exhaust manifold
Boost solenoid
 
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