range-rov fuel save mod

[skidmark77]

hi, just saw this mod on there website and if anyone has done it and at what cost and what were the results like
http://www.range-rov.com.au/22.html

[harry]

there certainly is room for improvement in the fuel system of land rover v8's, but if it's that simple, wouldn't the factory have done it themselves?

[JDNSW]

It was probably set that way to meet emission standards; a rich mixture may have proved necessary to keep Nitrogen Oxide emissions low enough.

It may also have been necessary to run the mixture rich to ensure that in all circumstances excessive combustion temperatures did not cause engine damage.

John

[moose]

Sturdy shoes and a big hole in the floor should save fuel!!:D

[njz]

Are they just changing it from open loop to closed loop?

The non-cat discos like mine don't have O2 sensors and run an open loop system. Without O2 sensors the 14CUX ECU looses the ability to be adaptive. With O2 sensors the ECU is able to determine whether the air/fuel ratio is lean, rich, or okay.
I think D1's from 98 have cats and run the closed loop system. The 14CUX has a tune resistor that can be changed to suit different world markets. I've read that later ECUs don't have the tune resistor and just run a different fuel map chip.

Given that it didn't come with cats from the factory I'm guessing they ran an open loop because our emission standards were a bit behind other countries and they could get away with not fitting cats or O2 sensors to save money.

Would they just be adding O2 sensors and changing the tune resistor or fuel map chip?

[PhilipA]

I have always wondered whether the circuitry is in our 14CUX to be able to run O2 sensors. The USA version has a diagnostic display as well as closed loop.
The 14CUX here does run much richer than 14.7 :1 . If O2 sensors could be fitted and the ECU go closed loop until say 50% throttle, then I am confident this would give a big improvement.
Anyone in Mebourne want to investigate?
Regards Philip A

[PeterM]

I asked them about this and essentially they simply put in the US tune and include an O2 sensor. For normal throttle positions the ECU takes it's input from the O2 sensor, when you go full throttle, the AF meter overrides it.

If you're sticking with petrol and plan on doing plenty of km yet, it isn't a bad option.

[disco-bob]

I asked them about this and essentially they simply put in the US tune and include an O2 sensor. For normal throttle positions the ECU takes it's input from the O2 sensor, when you go full throttle, the AF meter overrides it.

If you're sticking with petrol and plan on doing plenty of km yet, it isn't a bad option.

do you know how much they charge?

thanks rob.

[justinc]

All the wiring and support is there at the ECU ,( I even get a Lambda A and B output page on Rovacom for O2 sensor diagnostics...), there is just no wires at the ecu plug for the O2 sensors. These can easily be added, in the front engine pipes close to the join of the two primary pipes on each side.
I would then suspect that they actually change the tune select resistor value for the US spec, and it should work then. Interesting, I might give it a go.

JC

[PhilipA]

Justin, You get it done and report on it please.LOL

I have the added complications of Thor manifold, Bosch 23.5 Lb 4 hole injectors , and a unichip which also controls "vacuum" advance as well as fuel balance.

However I may call them to see if they can accommodate me. They would need access to a 4wheel dyno and unichip software.

I see this as by far the best solution to update a 14CUX.I already have one o2 fitting in front of my muffler to check my mixtures with a Jaycar kit. Maybe I have to get 2 more LOL.

I cannot believe that no specialist has thought of it before.
regards Philip A

[justinc]

Justin, You get it done and report on it please.LOL

I have the added complications of Thor manifold, Bosch 23.5 Lb 4 hole injectors , and a unichip which also controls "vacuum" advance as well as fuel balance.

However I may call them to see if they can accommodate me. They would need access to a 4wheel dyno and unichip software.

I see this as by far the best solution to update a 14CUX.I already have one o2 fitting in front of my muffler to check my mixtures with a Jaycar kit. Maybe I have to get 2 more LOL.

I cannot believe that no specialist has thought of it before.
regards Philip A

G day Phillip,

I had a vague passing thought of playing with this when I had a full pommy import catalyst Vogue SE in for some tuning etc some time ago. I suspected an O2 sensor failure with this one, but the misfire and poor running turned out to be distributor related. I noticed the different tune select resistor and the gaps in the ECU plug were filled with more wires (!) for the O2 sensors. But because I had removed my V8 at that point and was going diesel, I shelved the R and D ideas. Seeing this thread has reminded me about it again, and I have just the customer that would probably let me play with their RR....In the spirit of fuel economy of course!!

JC

[PhilipA]

Justin , I just had a look at the wiring diagram.
1 VIN after 451518 do not have a tune resistor ( vehicles with PRC8747 ECU ). This is from some time 1990.

2 The terminals 23 and 24 are sensor signal, and are screened ie coax
3 terminal 4 is an earth,in addition to chassis earths

4 The heaters are run from the fuel pump relay WO wire , which is parallel to the fuel pump.
They appear to be 3 wire o2 sensors.
Regards Philip A

[justinc]

Justin , I just had a look at the wiring diagram.
1 VIN after 451518 do not have a tune resistor ( vehicles with PRC8747 ECU ). This is from some time 1990.

2 The terminals 23 and 24 are sensor signal, and are screened ie coax
3 terminal 4 is an earth,in addition to chassis earths

4 The heaters are run from the fuel pump relay WO wire , which is parallel to the fuel pump.
They appear to be 3 wire o2 sensors.
Regards Philip A

Correct, thanks Phillip. I'll look into it as soon as I clear some of the work out. We are pretty busy ATM. I reckon if it can save people $10 per 100km, they'll be happy. I imagine though that it'll cost about $400.00 when you factor in say $90 per sensor, welding fittings for mounting sensors, tune select resistor (If required) is about $80 from memory, and the rest is labour for wiring mods etc?

Still might be worth it, I'll get back to you, and thanks for the wiring info.


JC

[PeterM]

Can't recall what the cost was for this, think it was about the $600 odd mark, maybe a bit more.

[mufflerman]

Correct, thanks Phillip. I'll look into it as soon as I clear some of the work out. We are pretty busy ATM. I reckon if it can save people $10 per 100km, they'll be happy. I imagine though that it'll cost about $400.00 when you factor in say $90 per sensor, welding fittings for mounting sensors, tune select resistor (If required) is about $80 from memory, and the rest is labour for wiring mods etc?

Still might be worth it, I'll get back to you, and thanks for the wiring info.


JC

Hey guy,s I've got an exhaust shop in Sydney (Five Dock) I was very interested to read this thread!, if your'e in Sydney I'd supply & fit the 02 sensors & plugs (ACA Sensors) at cost to see if it works, I've got a 93 v8 d1 non cat & made enquires with no luck re: input from 02 sensors to ecu I've got a diagram from RPI engineering (UK) that shows the pin outs in 14cux for 02 sensor connections & somewhat explains the different tune resistors

[PhilipA]

I have done a bit more research.
The Range Rovers use 3 wire titania sensors which have a reference 12volts in . These are more sophisticated and accurate than zirconia sensors.
The factory ones are also 12mm thread. I think most sensors in OZ are 18MM . Is it possible to easily get the 12mm fitting bungs? I suppose a nut would do.
I have found a US source for about USD30 each!!!! and I intend to order them as soon as the USD25 Bosch ones for my BMW arrive, and I confirm it is not all too good to be true.
Regards Philip A
PS looks like when all the facilities are used the old 14CUX is pretty sophisticated.

[PhilipA]

I have done more research today.
1 I have confirmed that the 14CUX has the circuitry inside. I checked a spare 14CUX I have and there are connections to circuits for terminals 23 and 24. There are no wires in the connector for 23,24, and 4 which are the ones used by the o2 sensors.
2 Our 14 CUXs have a tune resistor . It is Red PRC8005. To use the O2 sensors you need White PRC 8009 (according to RPI and I have no reason to doubt it). I have physically checked this, and I have a PRC 8009 on order from UK.
It is possible just to get a 3900 Ohm resistor from Jaycar but the PRC is encased in plastic with a plug for the loom. Plug and play no less. And it is only GBP 6 plus postage.
So all you need are 2 O2 sensors, to wire them to The ECU, get some power and a ground, and change the tune resistor and Voila!!
Regards Philip A

[justinc]

I have done more research today.
1 I have confirmed that the 14CUX has the circuitry inside. I checked a spare 14CUX I have and there are connections to circuits for terminals 23 and 24. There are no wires in the connector for 23,24, and 4 which are the ones used by the o2 sensors.
2 Our 14 CUXs have a tune resistor . It is Red PRC8005. To use the O2 sensors you need White PRC 8009 (according to RPI and I have no reason to doubt it). I have physically checked this, and I have a PRC 8009 on order from UK.
It is possible just to get a 3900 Ohm resistor from Jaycar but the PRC is encased in plastic with a plug for the loom. Plug and play no less. And it is only GBP 6 plus postage.
So all you need are 2 O2 sensors, to wire them to The ECU, get some power and a ground, and change the tune resistor and Voila!!
Regards Philip A

I'm glad you have the time Phillip, you are hereby appointed research fellow and test guinea pig for this project.:D:D
I have been watching with interest, and the furthest I had got was ascertaining that the catalyst 14CUX ECU has the pins connected, ours doesen't but as you mention, the ECU will support it. I have a realtime screen on Rovacom which will give me oxy sensor outputs etc so it helps to see that they are actually signalling etc. Keep going, and have fun.


JC

[PeterM]

Interesting mate. Keep us informed.