16.8mpg from a P38?? Hmmm....

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NikTheGeek

NikTheGeek

New Member
Posts
626
Location
Wigan
Clocked up my first 100 miles as a P38 Diesel owner and apparently, I'm getting 16.8mpg - and I did reset it first (inadvertently as I had the battery off).

I am going to give it an oil change and new filters all round. But where is the MAF sensor on these so I can clean that too (or check its not disconnected).

Should I suspect the EGR valve? If it were any other diesel car, the appropriate forum owners would be shouting "bypass it!!". I ran my previous car with an EGR bypass for 4 years and noticed an immediate improvement in low down performance and a *slight* improvement in mpg.

Any thoughts? What else should I look at?

tnx

Nik
 
Do your next 100 miles on the open road and report back.

I don't know Wigan but I believe that it has a newsworthy football team so it can't be a village.

16.8 round town sounds about right, particularly if it is short journeys from cold.

G~
 
its a 4x4 ! dont complain ! lol

if you want Economy get a prius ! haha

oh and yea, get the EGR bypassed, much smoother after and slightly more MPG
 
Dependant on year you may or may not have the MAF and EGR....

not sure when it was brought in, my 99 had it...and the MAF is in line with the air intake on the right hand sie of the engine bay (looking at it) and the EGR is on the the fron right hand top corner of the engine and is plumbed into the intake manifold....

I managed 25.2 average from my previous oil burner - and ignore the onboard computer - use the Brim to Brim method and work it our from that....

Fill up to the top, do some miles, fill up again, note the mileage and the litres used - do some maths:

Litres/4.54 = X

Miles/X = Miles per gallon

By far the more accurate method.
 
It certainly has an EGR as I've seen it. I've also seen the MAF in that case as there is a bulge with a connector and wires coming off it in the air intake, after the filter.

As for my first 100 miles, probably 25% was motorway, the rest short journeys.

As for Wigan, we have a premier league football team, a rugby team and a pier. So it's reasonably large! :)

Nik
 
on cold starts the fuel usage is phenomenal until it reaches operating temp. Start up and idle on mine and immediately reset the computer it starts at 10mpg then climbs quickly and stabilises at about 14/15 before dropping off again as the wheels aren't turning.

Once on the road and warm it climbs nicely and sits at 24/25 then tickling it along the motorway at 70 it will hold 32.

however i dont bother resetting it now and with over 1400 miles on the trip it shows 26.8 with a whole mix of driving.

A whole host of issues can create poor consumption incl binding brakes (seized caliper pins) binding transmission brake, siezed VCUs, driveline and transmission probs, flat tyres etc etc then there's the engine itself, poor quality/unchanged oil, blocked breathers, air temp sensors etc etc or just the general age of the engine.

As other forums have mentioned, do a brim to brim check on your fuel tank with some good old fashioned maths to work out your true MPG. Should be good this time of year as we're on summer diesel in the UK until later next month :D

If it is really 16.8 then you might as well have brought a V8! Expensive and fast instead of expensive and slow!
 
Last edited:
Saint.V8 said:
Fill up to the top, do some miles, fill up again, note the mileage and the litres used - do some maths:

Litres/4.54 = X

Miles/X = Miles per gallon

By far the more accurate method.
Click to expand...

Might also help you if you dont want to brim... 90 litres in the tank - each notch on the fuel gauge is 11 litres

0 litres - 88 litres.
(Taking 2-5 litres off the 90 for sludge and crap in the tank :D)
 
NikTheGeek said:
As for Wigan, we have a premier league football team, a rugby team and a pier. So it's reasonably large! :)

Nik
Click to expand...

I've been and stayed in wigan (once many years ago) you really have to be by the sea to have a Pier not an over grown posh canal layby in the middle of town.


Definition of pier
noun

  • 1a platform on pillars projecting from the shore into the sea, typically incorporating entertainment arcades and places to eat.
  • a structure projecting from the shore into a river, lake, or the sea, used as a landing stage for boats.
  • a breakwater or mole.
  • 2British a long, narrow structure projecting from an airport terminal, giving passengers access to an aircraft.
  • 3a solid support designed to sustain vertical pressure, in particular:
  • the pillar of an arch or supporting a bridge.
  • a wall between windows or other adjacent openings.

:rolleyes::rolleyes::rolleyes:


PS: I concour with the others 17 MPG is about right around town on short runs.
 
Last edited:
NikTheGeek said:
Clocked up my first 100 miles as a P38 Diesel owner and apparently, I'm getting 16.8mpg - and I did reset it first (inadvertently as I had the battery off).

I am going to give it an oil change and new filters all round. But where is the MAF sensor on these so I can clean that too (or check its not disconnected).

Should I suspect the EGR valve? If it were any other diesel car, the appropriate forum owners would be shouting "bypass it!!". I ran my previous car with an EGR bypass for 4 years and noticed an immediate improvement in low down performance and a *slight* improvement in mpg.

Any thoughts? What else should I look at?

tnx

Nik
Click to expand...

Never had mine down that low even when towing my caravan round the Pennines.
As others have suggested, check for binding brakes, seized VCU etc but also check the leak off pipes are not spilling fuel, that the in tank pump is working and the MAP sensor pipe is connected. Does your temperature gauge get up to normal temperature? Need also the check the temperature sensor for the EDC is working so diagnostics would be a good idea.
If the fuel computer re-set after the battery was off it may also be confused, re-set (zero trip 2) it next time you fill up and see what you get.
Short journeys in the cold can produce very low consumption figures.:eek:
 
Datatek said:
Never had mine down that low even when towing my caravan round the Pennines.
As others have suggested, check for binding brakes, seized VCU etc but also check the leak off pipes are not spilling fuel, that the in tank pump is working and the MAP sensor pipe is connected. Does your temperature gauge get up to normal temperature? Need also the check the temperature sensor for the EDC is working so diagnostics would be a good idea.
If the fuel computer re-set after the battery was off it may also be confused, re-set (zero trip 2) it next time you fill up and see what you get.
Short journeys in the cold can produce very low consumption figures.:eek:
Click to expand...

Been a newbie to range rovers what is the VCU? I know what MAF, MAP and EGR are from other cars, but not heard of VCU. Also, where is the MAP so I can check it? I think I found the MAF connection...

tnx

Nik
 
16.8 around town in stop start traffic at or below 30 mph is as much as you're going to get. At the governments fuel saving speed if it's an auto they drink the stuff. Look at your average speed on the trip computer, bet it's not a lot over 15 mph for the 100 miles. That is where the fuel is going. Get on the motorway at Wigan and take a trip to Preston. Set the comp as you get on the motorway and stick to a steady speed, anything above 50 mph bet you get 25 mpg plus. It's stop start in town that kills it.
 
Last edited:
goonarmy said:
is that calculated from fuel recpits too?
Click to expand...

No just off trip, which i find on mine is reasonably accurate. At 30 mph you will be doing around 1500 RPM, at 50 mph with lock up around 1750 RPM. Anyone who gets 25 mpg in stop start traffic around 30 mph has a miracle car. Landrover would like it back for tests. :D:D
 
Mine is reading about the same at the moment, to and from work which is only 4 miles so I believe that to be about normal, however I have played around with the driving styles since buying it,

Motorway; 50mph for 110 miles got it up to 36.
Motorway; 70+mph for 110 miles at around 28
Urban; shopping etc 50ish miles 26.

So all in all similar to the Td5 it replaced.

Tam
 
wammers said:
No just off trip, which i find on mine is reasonably accurate. At 30 mph you will be doing around 1500 RPM, at 50 mph with lock up around 1750 RPM. Anyone who gets 25 mpg in stop start traffic around 30 mph has a miracle car. Landrover would like it back for tests. :D:D
Click to expand...

greenslade said:
Thanks for this thread - it is making me feel a whole lot better about running a 4.6 V8 lol
Click to expand...

:D:DWammers I do love your sense of humor

:):):)I couldn't agree more lol!!!!!!!!!!
 
My first LR was a 3.9 v8 Classic, We had to part company due to the short runs to my work of 4 miles she managed around 12-14 when serviced dropping to single figures as time went by, Mitsi Pajero replaced that but missed the LR too much ;)
 
NikTheGeek said:
Been a newbie to range rovers what is the VCU? I know what MAF, MAP and EGR are from other cars, but not heard of VCU. Also, where is the MAP so I can check it? I think I found the MAF connection...

tnx

Nik
Click to expand...

MAP is located on the fuel filter housing and connected by a tube to the manifold. VCU is viscous coupling unit which serves as a diff lock for the centre diff. If it seizes it destroys the front diff etc. Check by jacking one front wheel, gear in neutral, you should with a lot of effort be able to turn the wheel.
 
Datatek said:
MAP is located on the fuel filter housing and connected by a tube to the manifold. VCU is viscous coupling unit which serves as a diff lock for the centre diff. If it seizes it destroys the front diff etc. Check by jacking one front wheel, gear in neutral, you should with a lot of effort be able to turn the wheel.
Click to expand...

Ok, done a VCU check. Well..... it depends what you mean by a lot of effort. I'm only a 10 stone weakling :) but I couldn't move the wheel with my hands or even with the supplied wheel wrench. I could if I stood on the wheel wrench, but it would only move a little. When I put my torque wrench on it, I could move it then but even on its maximum setting (140lbs) it was clicking to say I was over-torquing. But at least I could move it.

That ok? Or not...

Nik
 
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