P38 Fuel Consumption

[Rangie4600]

Hi All,

I am brand new to this forum but have been on the South Africa 4x4 Community one for some months mainly because I live in South Africa.

I have found very little advice regarding the Range Rover 4.6 HSE and see you guys have a fairly large group with some very good information available.

My problem is the very ugly fuel consumption I get from my 4.6 while driver very conservatively. I use it for commuting which consists of some 50% city and some 50% highway and I am struggling to get it under 20L/100 and this is without exceeding 100KM/H ever. I also find it is hunting a lot when cruising the highway with speed cruise on hills.

The vehicle is a 97 model with 220000KM on the clock and starts fine and generally does not miss a beat. It is fitted with a freeflow exhaust branches and no catalytic converters at all (They are not required in South Africa). It also has no Lambda sensors. I live in Johannesburg which is around 2000M above see level which results in around 15% power drop I am told. It is now run on 95 octane fuel which is the highest octane available at altitude where as at the coast it would run on the 98 octane stuff.

I have cleaned the MAF sensor changed spark plug leads and had a general look around. Does anyone know where I should start looking to find out where my fuel is going to?

Regards,

Jason

[bee utey]

Sadly the ECU has no way of knowing how much the mixture has wandered from optimum, exhaust sensors are very useful. The sages here will tell you how to fit and enable sensors, but a simpler idea is to use other means to reduce fuel flow. You could fit an adjustable fuel pressure regulator, adjust with the help if a dyno or air/fuel ratio meter. I have done so on an old Volvo 740 with reasonable success. They appear on ebay regularly, usually bought by turbo owners wanting increased power. They work both ways though!
Jaycar electronics Jaycar Electronics - Better. More Technical. (http://www.jaycar.com.au) have simple kits to adjust sensor outputs. Can be useful.

[p38arover]

There is also the P38A forum at: RangeRovers.net • View forum - Range Rover P38A Forum (http://www.rangerovers.net/forum/viewforum.php?f=3)

[Rangie4600]

Thanks guys for the advice,

I have been reading the forum and looked into chips such as the uni-chip which is very common here, fitted by a company called Steve’s Auto Clinic. Would this solve the problem?

Just to give you some idea of how I drive, took the wife out for valentines day to a game farm in the country. The round trip was 250KMs and her Merc A170 manual petrol with the aircon on all the time returned a fuel consumption figure of 6.1L/100KM. Now I am not looking for that with the Range Rover but on a similar trip I would like the Range Rover to return about double.

Thanks for the advice.

Jason

[p38arover]

The round trip was 250KMs and her Merc A170 manual petrol with the aircon on all the time returned a fuel consumption figure of 6.1L/100KM. Now I am not looking for that with the Range Rover but on a similar trip I would like the Range Rover to return about double.

:D:D:D

Sorry, couldn't help myself. You'd better buy a diesel.

That's 16 litres/100km. A petrol P38 will use about the same on a trip.

[Junosi]

Does anyone know where I should start looking to find out where my fuel is going to?

I'd be booking it in to get a testbook tune. They'll take a look at your exhaust gas and adjust your fuel trims to the correct level. It might be set for sea level which would be too rich for your altitude (not enough oxygen up there) which would make it thirsty to run. If your car had lambda sensors in the exhausts it would be adjusting these figures itself (fuel trims) but without them its running blind.

You'd be hard pressed to get a Range Rover to average 12l/100kms.... 16-17l/100kms would be much more normal or in the low 20's if you do a lot of stop/start driving. Their problem is their weight as much as anything, takes a lot of fuel to get 2.5tonne up and running - once its rolling though its not too bad :D

ps be careful about buying a 're-chip' - some of them require lambda sensors to operate correctly

[Hoges]

For info: did 3,700 km over Christmas-New Year BNE-SYD-CBR-Kiama-CBR-BNE including suburban stop start in Sydney and CBR.

Overall 14.2L/100km measured by GPS distance and fuel fill ...aircon on all time. 3pax and loaded w luggage + toolkit (extensive;))

Best was 10.5l/100km for the home trip section CBR-Pennant Hills (approx 280km) and using the ginormous ring road from Liverpool.

Worst was Kiama-CBR (up Macquarie Pass) and CBR round town etc...approx 18.5L/100km.

Av speed for whole trip was a shade under 75kmh, sat on 100-105 all way home to Bris (via Pacific Hwy).

cheers

[Aussie]

I quite regulally get very low 12's L/100k on trips over 200k's,around town I am getting 16L, I am using 98 octane

[Junosi]

*average* is the key word here. Mine is in the 12's on a long trip, but nearer to 20 round town. My average over the last 5000 k's is 16.1

[Rangie4600]

Thanks again for the feedback,

That comment about buying a diesel may not be a bad idea but have never liked them, a bit smelly and noisy and I don't really understand how they work.

I have been avoiding going to a dealer, the cost is the scary bit. I maintained my old series 3 for 10 years without ever needing a dealer, I guess this beast is a little more technical.

I did notice it ran a bit better on 95 octane rather than 91 but you are probably right it is running too rich. Oh well time for a tune up at a dealer then!!

What would be involved in fitting the O2 sensors and would they just plug in somewhere?

Would the system retune itself properly?

[Junosi]

What would be involved in fitting the O2 sensors and would they just plug in somewhere?

I retro fitted lamda sensors to mine a few weeks ago, but I was lucky enough to have the wiring loom with two plugs sitting there under the engine already. If my engine hadn't of had the wiring there I'm not sure I'd of bothered.

You can check if you've got the wiring underneath easily enough. Have a look under the engine, on either side of the sump area might be a empty square plug. At least that's were mine were. My cables and plugs were tied up with a cable tie to stop them dangling.

If you do have them you need to buy and fit the lamda sensors to the exhaust at where the start of the catalytic convertors would of been. British eBay was the cheapest source I could find for the correct lambdas. Fitting was easy, just a hole made and a nut welded on. After that you'd still need to visit a testbook dealer to get the engine computer to recognize them and start operating in 'closed loop' mode. Or buy a new chipset that has them enabled already (unichip, tornado etc)

[Rangie4600]

Thanks Junosi,

I will be having a scratch round under the truck this weekend.

You say you would not have bothered if you didn't already have the wires, is this because it has made no difference to performance?

[Junosi]

is this because it has made no difference to performance?

I installed mine specifically to allow me to install a 'Tornado' chipset from Mark Adams. Before that my car was running quite well with no lambdas in 'open loop' fuelling mode averaging around 16l/100kms. But as I wanted the Tornado installed I had to have lambdas so I put them in - and now its rechipped and noticably more powerful - particularly at mid to high revs. If I hadn't been rechipping I wouldn't have gone down this road. Alternatively Mark Adams does a chip for P38's with no lambdas - but after speaking with Mark he convinced me I was better off going with the lambda version as the chipset can take better advantage that way.

If your P38 is tuned properly then there's nothing wrong with running in 'open loop' mode and no lambdas - like all early Australian and apparently South African ones are :) My guess though is that yours is tuned for sea level fuelling and therefore running rich at 2000m altitude, if you retuned it for 2000m then when you do run at sea level you'd likely be lean =/ Lambdas should auto-correct that condition by adjusting fuelling depending on conditions. A $20 eBay elmscan would let you see the fuel trim figures if you're interested via the cars OBD port, basic elmscan will read and reset engine ODB but will not do all the other Range Rover stuff (abs, airbags etc). Short term fuel trim of +24% is the maximum figure you could see - I'm not sure what it should be reading at 2000m. Mines on around -18% for comparison, at idle and 200m elevation.

One way or another you've got to find out what's going on with your fuelling anyways.

[Rangie4600]

Hi Junosi,

I think you are spot on, I need to know where my fuelling is currently.

Would you be able to send me a link to a suitable Elmscan tool that I could purchase, does not matter if it is in Australia or the UK as I can have it sent internationally.

[Junosi]

I bought my scanner on eBay from china (I'm an eBay junky :D)

Here's a link to the one I think I bought - $27aud now apparently Scan tool Automotive OBD OBD2 ODB Diagnostic Scanner - eBay Other, Tools, Car Parts, Accessories, Cars, Bikes, Boats. (end time 17-Feb-10 04:28:11 AEDST) (http://cgi.ebay.com.au/Scan-tool-Automotive-OBD-OBD2-ODB-Diagnostic-Scanner_W0QQitemZ370177857221QQcmdZViewItemQQptZAU _Car_Parts_Accessories?hash=item563051d6c5)

or search eBay for 'OBD scanner' - genuine 'elmscan' scanners cost somewhat more than the knockoffs and don't do anything more. They shoud all do engine obd. There's plenty of info on the forums about the real Range Rover scanners that do the lot if you've got spare cash - faultmate, blackbox, autologic etc.

Keep in mind you'll need a computer/laptop to talk to the scanner - with either usb or serial connector depending which one you buy (mines a USB one). The OBD software they come with is pretty basic but functional enough for engine figures and fault resetting. Other free or trial software includes 'scantool', 'easy obd', 'scanmaster', 'obd2spy'

[Rangie4600]

Thanks Junosi,

I will be setting up my paypal account tonight and will order one. AS for laptops, I am in IT so not a problem.

I have posted on forums here in SA an no one really know anything about retrofitting O2 sensors but will keep asking. Time to pay a dealer a visit:(

[Rangie4600]

So I had a look and my 97 RR does have the O2 sensor plugs (2 jacks with 4 wires each).

Does anyone know exactly which O2 sensors I need to buy?

What exactly do I have to tell the Landrover dealers when I want them to enable the O2 sensors on TestBook? This is Africa they are not that sharp around here or is there any other way to enable the sensors?

[p38arover]

The question really is - can the sensors be activated with Testbook? The non-sensor and sensor ECUs have different part nos.

If Testbook can adapt them, why is this necessary?

[Rangie4600]

hey p38arover,

You have just crushed my dreams, I didn't know they had different part numbers. This may send me back to the drawing board for ideas.

[p38arover]

If the ECU can be changed with Testbook, I'd certainly like to know 'cos I'd try fitting the sensors.

I have Testbook in the garage.

There are so many ECUs and they are market specific.

Looking at MicroCat, all the Australian ECUs appear to have superceded to a single model. Perhaps this later one can be upgraded with Testbook.

[Junosi]

I'm not sure if the ecu can just be 'enabled' in testbook to pick up lambdas or not. I got no conclusive answers when I went through this myself. Both of Melbournes biggest Land Rover dealers (MLR and Ritter) couldn't give me a straight answer either.

After hearing that from Ritter and MLR I was disappointed myself as I wanted lambdas. So I thought I'd replace the ecu with a lambda enabled ecu. They're relatively cheap on eBay (approx $100). There's a bit of hassle involved in putting a new ecu in which I'm not up to speed on, invariably a trip to testbook would be required at least to sort out security issues.

As it turned out I circumvented the need of a new ecu by replacing my standard ecu's chipset with the Tornado chips - which have lambda input programming. The moment my lambdas were plugged in they were enabled. If Rangie4600 has the loom there (sounds like he does) then rechipping should be a viable solution too - assuming a lambda chipset was installed...

[Scouse]

I got no conclusive answers when I went through this myself. Both of Melbournes biggest Land Rover dealers (MLR and Ritter) couldn't give me a straight answer either.

After hearing that from Ritter and MLR I was disappointed myself as I wanted lambdas. Unfortunately, the powers that be frown upon any dealers performing modifications to cars. A dealer would normally be the last to ask about this sort of work as all they usually deal with is repairing standard cars.

[Rangie4600]

Hi,

I have been searching this forum for something I once read about testbook being able to change the chip setting to be able to read Lambda's. I just cant seem to find it.

P38aRover, you have a testbook, do you think it is possible? Having never even seen a testbook I have no idea how complicated it is to use.

[p38arover]

To be honest, I've never looked at that area with Testbook (mine is a T4).

Testbook is easy to use but slow - it must add to the cost one pays at a dealer!

[Rangie4600]

I am going to try prodding a few people over here for information, but from the sounds of things you guys are more clued up than we are.

The options are:
Either get hold of a second hand cheap chip with Lambda’s enabled and overcome security issues
OR
Enable Lambda's on the existing chip

Do you guys know what a Tornado chip costs in Australia because they are on sale in the UK for 800GBP which is rather steep?

[p38arover]

Why not ask Bruce Davis at Davis Performance Landys in Oz about his chip? I now have one in my P38A. It's cheaper than the Tornado.

I suspect RSA spec cars are the same as ours.

See http://www.davisperformance.com/rangerover.html

[Rangie4600]

Arround here most people use the UNI-CHIP fitted by SAC

Petrol Performance Power Enhancement Conversions Modifications Engine Upgrades (http://www.steves.co.za/Conversions_petrol.html)

I know they are used in Australia, do you know anything about them?

[Junosi]

The options are:
Either get hold of a second hand cheap chip with Lambda’s enabled and overcome security issues
OR
Enable Lambda's on the existing chip

There won't be any security issues with an aftermarket chipset - they just plug and play using your existing ECU. Another option is to replace your current ECU with a used one that has lambda input, they're relatively cheap on the UK market ($100). Not sure what's involved in that - at the very least it needs to be put on testbook to overcome the security problems that would ensue with replacing an ECU.

And yes, Tornado chips are pricey - but well regarded. No idea on unichip etc.

[Aussie]

Why not ask Bruce Davis at Davis Performance Landys in Oz about his chip? I now have one in my P38A. It's cheaper than the Tornado.

Whats your impression of the CHIP Ron?

[Remy]

Why not ask Bruce Davis at Davis Performance Landys in Oz about his chip? I now have one in my P38A. It's cheaper than the Tornado.

I suspect RSA spec cars are the same as ours.

See Range Rover Performance Upgrade (http://www.davisperformance.com/rangerover.html)

What happened to the Haltech?

[33chinacars]

Here's what the ''Tyrendarra Tractor '' did . Just been on a trip to Melbourne & back last 2 days. 900 Kms Total[ 600kms country driving( mostly at legal speeds MOSTLY :angel: 100-110 kph, 300 kms ultra urban/urban including some peak hour traffic] Figures as per trip computer 14 l/ 100 kms at an average speed of 75 kph. Did fuel check 14.05 l/ 100 kms.
Trip computor did read 13.5 l/ 100 before getting back in traffic. I'm not complaining as a lot of this was with car's air suspension stuck in high/ extended mode:wasntme:.
Most of my driving will be country miles