Poor economy from a V8 RRC...

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My 1990 Classic on LPG averages 12 around town and 18 on a run, so I guess adding on approx 10% for petrol I'm not alot in front of you!! And that had a full service the week after I got it, all oils and fluids, filters and plugs and she runs as sweet as a nut so don't think I could improve too much. To be honest I wasn't expecting much more from a 20 year old V8 and the LPG softens the blow.

The P38 is only averaging 13mpg in this weather (mostly stop start stuff) and we are seriously thinking of going down the diesel route :eek: The ludicrous rise in price of LPG in the last few weeks is fast making that option a no no. Even if you can afford it the price of petrol at the moment is making these things less appealing to run.
 
I dont know if this will help, but my 1997 P38 petrol has been running very rich. All plugs are black and eventually plugs foul. Fuel usage has at least doubled. When I cleaned plugs disconnected Mass Air Flow sensor, vehicle ran like a dream for a couple of days, but then it stated popping and missfiring. I have got a Faultmate Extreeme and confirmed that MAF voltage into ECU at idle was 1.6V should be 0.6V. I am now suspecting MAF sensor. Although I guess your RR is a 1991 so may not have MAF sensor.
Cheers Alan
 
don`t know if this has already been said but can`t be arsed to read through the thread, but surely the clue is in the title... poor economy + V8 = answer ;)
 
the front spoiler thingy is there to INCREASE mpg,remove and lose 2-4mpg...
 
I have a 4.6 2001,around the town she does 12-13 however on a run 30-60mph its always up to 24-25..Best yet is staffs to Anglesey about 120 miles and 26.7mpg no traffic and 55mph in cruise.
 
I dont know if this will help, but my 1997 P38 petrol has been running very rich. All plugs are black and eventually plugs foul. Fuel usage has at least doubled. When I cleaned plugs disconnected Mass Air Flow sensor, vehicle ran like a dream for a couple of days, but then it stated popping and missfiring. I have got a Faultmate Extreeme and confirmed that MAF voltage into ECU at idle was 1.6V should be 0.6V. I am now suspecting MAF sensor. Although I guess your RR is a 1991 so may not have MAF sensor.
Cheers Alan

Yeah the '91 does have a MAF sensor so will give that a clean over the weekend and see if it helps!

Cheers!
 
Ehhhhhhhhhhhhhhh.......Common sense FFS.....:rolleyes:
Rather than land rovers own documentaion. In the hand book it clearly states that removing the front spoiler will give you 2-3 mpg more.

Although not sure what comon sence you are using.. as anything that is designed to change the airflow will increse drag. Spoliers and splitters normally increse drag and thus fuel consumption
 
Rather than land rovers own documentaion. In the hand book it clearly states that removing the front spoiler will give you 2-3 mpg more.

Although not sure what comon sence you are using.. as anything that is designed to change the airflow will increse drag. Spoliers and splitters normally increse drag and thus fuel consumption
thats wot i thought, wil check tonight.
 
Having an engine running rich will make a big difference to fuel consumption. Before you spend any money on parts, its always best to try and diagnose and a faulty stat should not be too difficult!. I've not checked but the stat will probablybe a 82 or 88C. Run engine from cold &measure the cylinder head metal temp near the stat housing it will be within 2 or 3 C of coolant temp and it should rise to 80 to 85ish before the top of the radiator starts getting warm. Use an infra red thermometer. These devices are very usefull, it can be used also on exhaust manifolds to diagnose engine running problems like misfires, injector problems, cooling problems etc. hope this helps
 
Rather than land rovers own documentaion. In the hand book it clearly states that removing the front spoiler will give you 2-3 mpg more.

Although not sure what comon sence you are using.. as anything that is designed to change the airflow will increse drag. Spoliers and splitters normally increse drag and thus fuel consumption

:confused:
 
Some of the difference could be down to driving styles too... when K drives Ruby, she gets less mpg than I do, same car driven differently... plus with a V8 a few extra kick downs will soon drink some jiuce!
 
Yer all stating stuff of fantasy to me.
Mine still only doing about 8mpg, had it up to 14 on a run once, constant 55-60 mph, no stop starts, no traffic.
Got used to it now and even though the LPG has gone up, it still close enough to 1/2 the price of petrol for me.
Is the claimed figures for P38's taken from the onboard computer? Mine said 24.6 mpg but when I'd filled up and done the sums, the truth was 14 mpg.

That said, 11mpg on a run isn't anywhere near what it should be, lambda sensors (if fitted) air filter, plugs, all can be responsible for crappy MPG.
 
I've been using my 4.0 P38 consitently over the passed 4 weeks after replacing 2 lambda sensors, MAF meter and service. It's returning me 24 - 25 on the Motorway at a steady 50 - 60 mph and about 17.5 around town that going by what the computer is displaying.
 
I've been using my 4.0 P38 consitently over the passed 4 weeks after replacing 2 lambda sensors, MAF meter and service. It's returning me 24 - 25 on the Motorway at a steady 50 - 60 mph and about 17.5 around town that going by what the computer is displaying.


computer is lying............fill up know amount then count how many miles you get on it.
 
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