Thread: 1990 3.9i, appalling fuel consumption

What exactly is it about a Range Rover that makes people commute in them, then complain about the fuel consumption? They are as aerodynamic as a brick outhouse. The engines are low compression so that their primitive engine management can cope with third world fuel.

If you like the V8 raise the compression to around 10:1, fit a better ignition management system, fit oxy sensors, run premium fuel, get a LPG conversion.

If you like a diesel get a 300TDi, fit lpg enhancement. A donor D1 is the best way to achieve this. Anything else costs zillions.

Otherwise commute in a Corolla.

... thats what makes us use the R/Rover as a daily drive... can't find anything else thats equally solid and comfortable..

Originally Posted by PhilipA

I just reviewed the posts on this thread, and it seems that all that has been done is to check the temp sensor so far.

Are the comments about the Rover v8 helpful? Or funny?
Chris has a problem .
My picks would be
1 temp sensor
2 vacuum advance. Chris suck on the hose and see if it sticks to your tongue. If not replace.
3 MAF. Chris, take off the MAF and spray the little hole you will see through the screen with electronic cleaning spray available form Jaycar. Dry it out and refit. In the connector tweak the little blades gently about 5degrees with a pair of needle nose pliers.
If none of that helps, the problem is deeper such as a worn out cam.
Regards Philip A

1 - already replaced but iv yet to check the resistance as recommended on here, to confirm its working. will check and see when i get a chance!

2 - vacuum advance test done and it holds pressure

3 - MAF iv tryed with the maf that pete (pierre) lent me, unfortunately no real difference.

I had the car at Romsey LR centre this week to replace the water pump, and i mentioned the problem with fuel consumption. he adjusted the ign. timing slightly but didnt seem to think it would make much difference (it hasnt!). His thinking is that considering the mud tyres, suspension lift and roof rack , what i am getting sounds about right.

However I have a 110 3.5 v8 on carbs, back in england. That achieves better mpg despite have larger tyres (285/75s against 265/70s), and a larger roofrack. Am i wrong to expect the rangie being a more modern, fuel injected injun, and a smaller, slightly! more aerodynamic car to acheive similar or better mpg?

Originally Posted by chris_mack

Am i wrong to expect the rangie being a more modern, fuel injected injun, and a smaller, slightly! more aerodynamic car to acheive similar or better mpg?

Given the right conditions ... The old carby motor can achieve better MPG than a EFI


Have you tried the most simplest of things ...and given the fuel tank a dose of Injector cleaner?

I have seen excellent figures, 22+ MPG, out of a Hi comp carb 1983 4 spd manual 4 door. Driven at sensible speeds, these are quite economical but best of all still sound/ feel like a V8.

Just hard to find a good example now


JC

I agree. My 77 used to get up to 23MPG on the flat. After I fitted Federal injection , it did not improve one bit.

I believe the auto uses more in anything but plus 85Kmh on flat ground.
Weight of course is the enemy.
Regards Philip A

Justin chime in here as you have probably seen more Lucas Vac Advance units than I have had hot dinners.

Doing a test on vacuum advance that only entails checking if they hold pressure is NOT ENOUGH. These units are shot long before the diaphragm either splits or loses it seal around the edge revealed by the leak test.

The rubber diaphragm in the advance unit starts to become stiff and shrink after only a few years service. That translates to the vac advance kicking in later and coming to an end too late (useless when richer fuel map has already started to be seen) or not even reaching the maximum advance it is supposed to deliver as the amount of vacuum at throttle plate starts to decrease.

I have seen rubber diaphragm shrink so much that initial advance is 10° out when fitting a new unit. Yes ….a must do is check timing when fitting a new vac unit.

If you don’t have a vacuum pump to check health of the diaphragm one quick test is to plot the amount of mechanical advance at say 250 RPM steps both with and without vacuum connected. Vac advance should kick in by 1,100 RPM and majority of vacuum advance component of say 15° be all in by 2,250 RPM and certainly all in by no later than 2,500 RPM (at no load). If not and say vac advance is still working beyond 3,000 RPM and doing most of its work between 2,000 and 3,000 RPM then its is either well past its use by date or the wrong unit for a EFI RV8. Note this is test only as vac/RPM are different under load. Don't have a timing light/tacho....here is one...LOL http://www.aulro.com/apc/showproduct...ct/3846/cat/24

I have seen Lucas EFI vac units with different style nose cans (with a shoulder and with no shoulder) and stamped (where 1st and 2nd # are the start and finish vac pressures in inches mercury and last # is advance in dizzy degrees so double for crank advance) and some unstamped. Seems to me what advance unit a dizzy got was lottery at the lucas factory???

Someone else might know what the specific design operating pressures and the amount of vacuum advance for each RV8 EFI engine setup are to enable proper checking of dizzy with a vacuum pump.

Yep, got a bottle of Nulon injector clean in there now.. did a couple of hundred k's up and down a freeway - at speed limit only!- and managed 5.77km/l = 16.3mpg = 17.36 l/100km
- Feeling a bit happier !

James