qd32 using too much fuel

[Matt Mc]

Hi, i own a 1998 qd32 navara, it is using 80L in 500klms on the highway. i have just installed new injectors and there is no change i changed the fuel filter reciently too. iv checked the bango filter it was spotless. it has 200,000klms on the truck, snorkle, 31" bighorns 2'' sus lift.
is there any other reasons for it to be using this much fuel? cheers

 

[Old.Tony]

The bigger tyres won't help a lot and at highway speeds even our 2.5L CRTD engines consume more than they ought to. The trick is to find out where the torque curve of your engine starts to level out after its steep rise - around that point is the most efficient fuel->power production. In my car, that's about 2,000rpm or 95km/h on the highway.

As an example, with a nearly full load, mine uses 10.6LPHK when cruising at 95km/h and 12.1LPHK when cruising at 110km/h.

You could also block the EGR valve. Not sure how difficult that will be in yours, but allowing the EGR in to dampen the combustion does reduce the efficiency of the engine.

 

[Matt Mc]

okay thanks mate, myn doesnt have a tacho so im not sure what im sitting on but i dont usuall go over 100 anyway. where is the egr valve abouts? thanks

 

[Old.Tony]

I'm not sure on the QD32 - I am more familiar with the YD25. There will be a metal pipe that comes off the exhaust manifold and runs around to a gizmo attached to the intake manifold. The gizmo is the EGR valve, which allows exhaust gas to flow into the manifold during mid-range throttle operation (which is most of the time you're driving).

They only started putting flow sensors in the valves around 2011-2012, so you should be able to just block yours. Remove the gasket, draw its outline on a piece of stainless steel at least 1mm thick, then drill the bolt holes and leave the centre blocked. Reassemble using sensor-safe gasket cement (eg Permatex Ultra Blue for about $18 at SuperCheap Auto) and it's done.

 

[Matt Mc]

okay thanks heaps mate

 

[Dave]

Get the timing and the injector crack pressure checked.