D40 sluggish up hills and driving on highway

[Aus]

Hi all I have a 09 Spain Titanium Edition YD25 (126kw) Navara. I've had it for almost a year and a half now. Been on hard tracks, water crossings, beach, etc. I also use it as my daily to work. (220km weekly). I'm gonna be touring NSW this christmas and want to make sure it's got it's power and fuel economy back for the touring trip. For the past 5 months it's been struggling to drive even itself around. It's fine around town, but as soon as you shift into 5th & 6th for driving on highways it's got no balls. Wants to stay boosting over 5 - 20 psi even on the smallest of hills not towing anything and loses speed. It's been getting to the point where even 4th gear up hills it's had to boost over 18psi just to keep up to speed. Overtaking is annoying. Hates towing anything over 1 ton and even small box trailers, will boost into 15psi trying to stay on 100kmp/h towing in 4th or 5th. Cranks first thing on cold or warm mornings. Does soot when hard accelerating. Can get 450 - 600km a tank not towing. Towing around 450 if lucky.

I'm the second owner of this navara. Had 163,000km when I got it. Drove great, good acceleration up hills.

185,700km later
Been to multiple mechanics
Stock turbo with no tunes or chips, all fluids have been changed.
Temps are between 84 - 95 degrees even on a hot day up hills.
Only thing I haven't touched is the fuel tank or MAP sensor. (MAP is Genuine)

Oil every 10k with Penrite 10w-40
Genuine oil filter
Genuine Nissan SCV
Genuine Nissan boost solenoid
Genuine fuel filter
Genuine MAF sensor (Tried cleaning it first)
Double row timing chain from YD25
EGR block from YD25
Intake was cleaned for carbon
Intercooler was flushed
Plazmaman Turbo hotside pipe
All Vacuum hoses for boost system
ECU/Fuel pump reset with a G-scan tool
3 inch playtime turbo back exhaust CAT/MUFF
EVC Throttle controller
Exedy SMF HD clutch
32 inch tyres with 2 inch lift
Safari Snorkel
Has bar/winch, and a few other accessories
Ute weights in at 2.5 Ton with no driver


Appreciate any help.
Cheers.

 

[Old.Tony]

Welcome aboard.

Same year model as mine (although mine's an auto).

I wouldn't sweat on the boost levels. Boost can be anywhere the ECU needs it, up to around 22-23psi. I'm guessing that you're still using the BCS, therefore ECU-controlled boost? That does raise one possibility.

Part of the ECU's programming is to keep boost reduced when the car's not in gear. In your model, this is controlled by a neutral switch on the gearbox. It's really easy to test - because the switch is "off" (no continuity) when in gear, simply unplugging it tells the ECU that it's in gear.

On the right hand side of the gearbox near the rear are two plugs. The lower one is the reverse switch and the upper is the "PNP" (Park/Neutral Position) switch. Just unplug the upper one and drive the car. If 5th & 6th gear now drive better, the problem is that switch, which you can replace at your leisure, because leaving the neutral switch unplugged isn't going to break the gearbox, loosen wheelnuts or cause Catholic nuns to have heart attacks.