Thread: Stalling d1 and using heaps of fuel

The MAF certainly has an idle mixture adjustment screw, I'd think that having a go at it would be a good idea, possibly with the help of a CO meter or a temporary O2 sensor. However first of all I'd disconnect the little vacuum hose running between the fuel pressure regulator and the inlet manifold and look for signs of liquid fuel. They are a known failure item, I've replaced a few on various vehicles, including LRV8's.

The Maf mixture screw is set and blocked by a blanking plug from factory and it can be removed, but why would a maf even need adjusting now, unless it was faulty?

Originally Posted by Roverlord off road spares

... but why would a maf even need adjusting now, unless it was faulty?

Things that I can think of without raising a sweat:

Component values in the 14CUX drifting with age

Fuel mixes different to 20 years ago

Fuel pressure different due to worn pressure regulator

Injectors worn or replaced with slightly different spec ones.

Factory settings a ballsup from day 1.

Remember that D1's in Oz don't use O2 sensors and have no way of fine tuning themselves. Capping the adjuster is good for the warranty period, long since over, now just an annoyance. I've met loads and loads and loads of stinking rich running D1's during my LPG conversion peak times, if I knew then what I know now I would have adjusted around 80% of them.

Originally Posted by MartynBrisbane

Hi All,
I have a 96 discovery series 1 3.9 V8.
It has been running rich(you can smell it) for as far as I can remember, but as its a third car, it doesnt get used much so hasnt bothered me. Its now starting to stall and now its bothering me!
She's using approx 30 l/100klm.
Things I have recently done to try and rectify this:
new plugs, leads,coil, dizzy, rotor, maf sensor, iac valve and engine coolant temp. These things have done nought.(although, it does seem smoother now)
Not sure what is next! BTW, do I need to 'set' the maf sensor?
Cheers,
Martyn

You say that you have "done" the IAC valve, what does done mean, did you replace it, did you test it to see if the stepper motor actually works, did you decoke the actual valve and seat.
I have fixed a few Disco's with your exact same symptoms, the following was the cause in most cases:
I have found that the valve body was loose, the allen bolts were not tight, the electrical plug was loose and needed cleaning, the actual cone shaped valve was coked up as was the seat it's supposed to seal in, or the stepper motor was not working and on many occasions, what bee utey said about the vacuum line to the fuel regulator, I also found that by cleaning the MAF electrical plug with Contact cleaner and spreading the pins a bit with a small flat blade screwdriver also fixed the problem, so if you haven't 'DONE" or at least checked any of these you should have another look, good luck, Regards Frank

Check fuel pressure. Had it before, when they sit, the fuel pressure reg sticks and gives it too much fuel.

You can adjust the mixture easily on the MAF but only when its running right.
From memory put a multi-meter between ground and the red wire (i think) and voltage should be about .8v...as you adjust the screw it should change.

Yeah, Sorry, Done means replaced!