Nissan Navara D22 STR - Poor fuel economy and loss of power up hills

[Callam]

Gday

I've had my 2012 Nissan Navara STR 2.5L for about 6 months and recently the fuel economy is getting worse (about 6km/L down from 11km/L) and I seem to be losing power when going up hills and have to drop down to second gear to make it up
My previous car was a 2002 Nissan Navara STR 3.0L and it gets around 12km/L and has never had any trouble going up hills
The power difference is massive
I keep seeing people saying they made the 2.5L more efficient and powerful but I think the opposite

I have had my vehicle checked by a Nissan Dealership that found no issues and even said my fuel economy was normal which is not true obviously
I asked them to look into it more but they belittled me and ignored any concerns I had

Is there any known problems that can cause such a decline in performance because it's starting to frustrate me and make me reconsider selling my old navara

 

[Petunia]

Boost sensor? Splits in vacuum hoses? Gearbox neutral sensor? Timing/valve clearance? I am only guessing, because 2nd up a hill sounds is awfully gutless, and economy is pathetic.

 

[maddon]

mate ; i got the same vehicle but a 2010 and its a gutless heap / its called bob - bucket of bolts - but the economy is fantastic , that being said it has paid for itself twice and at almost 400 thousand klms done some fantastic campaigns from cape york to deserts , high country blah blah there must be someone out there that can help you out -- i wouldnt have a clue , petunia might have a clue , there is the crank angle sensor too and of course the timing chain which is a big dollar item especially with a double chain conversion from the states // hope you get it sorted out soon // good luck

 

[2002GU3]

G'day Callam, have a look at "Patrol 4x4 " they have a Navara section, maybe the blokes there can give you some help.

 

[Belfy82]

Hi Callum

My best guess would egr soot build up in intake restricting air flow. I'd assume the yd25 has egr?

 

[Almostunseen]

How many Kay's?
After eliminating any boost or hose issues:
Buildup of carbon is a big one in these engines, as @Belfy82 mentions, taking the manifold+EGR off and having a look you may be surprised.

Test the NPS (Neutral Position switch) by flicking the "Heat" switch at the drivers right knee, Revs should go up to high idle if gearstick is in centre, then depress clutch and try all the gears, the revs should drop to normal idle.

Doing the Liquimoly Diesel purge may help once you've eliminated all other things.

D22 YD25 Liqui Moly Diesel Purge

Hey guys/girls I recently found on this forum a thread on Liqui Moly Diesel Purge which was based in the D40 thread. after much hunting and hesitation i purchased this stuff and went about "Purging" the motor. Below is a list of tools and products needed: (remember some of these things can be...

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