Gutless and Thirsty

[NevTheNav]

Looking for opinions;
The last 1000kms the car has been a bit gutless (not limp mode issue, just have to really push it to get anywhere quick), and fuel economy has gotten ridiculous, I would normally get 600kms to a tank, am getting 400 all highway driving.
I've recently replaced the SCV, could this be failing and causing my issues or something unrelated?

Will be taking it to the mechanic once I'm back from holiday, just want to know what to expect

 

[Old.Tony]

There are a number of things it could be.

* Dirty MAFS - don't clean it with anything solid, always use a spray cleaner.

* Dirty SCV/injectors. Might want a doe of Liqui Moly Fuel System Treatment or go all the way and do a Diesel Purge.

* Dirty intercooler. Pop off the front grille, two bolts, two hose clamps and she's out. 100ml of unleaded, cup one hand on each opening, turn it upside down at various angles until the fuel's gone through a couple of times. I found it handy to slightly relax the upper hand to stop the intercooler from pressurising. Empty it out, then repeat until the fuel comes out near the same colour it went in (took 5 goes on mine).

* Boost leak. Look for the tell-tale signs of oil spatter from the pressured hose between the turbocharger and the inlet manifold4

* EGR valve failing. Block it.

* Failing turbocharger or control components. This is a bit scary. Check if the actuator arm that goes into the turbo moves when the engine is idling/revved slightly. If not, remove the hose from the top of the turbocharger and attach a fresh 3mm hose to it. Suck on the other end and look at the arm beneath - if it moves, the actuator is ok but the hoses, solenoid or vac pump or brake booster may have issues. Usually your braking suffers if it's the booster. Check how much boost you get - a moderate acceleration should see over 10psi of boost. If you're not seeing that, your turbo bearings might be failing.

 

[Black_Outlaw]

Diesel Purge and Diesel Throttle body cleaner.. Clean out the intake and fuel system.

Check all boost lines (replace if you've never done then and they are older then 2 years), and check your Boost Control Solenoid is functioning (a high fail part in Navara's). Ensure you're getting a goof vacuum from the vacuum pump boost line to the Boost Control Solenoid.

Check and clean Air Filter / MAF and the air path / hoses / intercooler.

Do a Pump Reset and Learn..

Test and report back.

 

[NDS410]

I'd be doing the Fuel Filter before anything else...