Thread: range-rov fuel save mod

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

Originally Posted by 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

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

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

Originally Posted by justinc

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

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.

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

Originally Posted by 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

I'm glad you have the time Phillip, you are hereby appointed research fellow and test guinea pig for this project.
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