3.9 14CUX

[NJV6]

I have got my 3.9 running (serpentine belt - 14CUX) but have a couple of questions. The motor is not in a Disco anymore.

There is heaps of info about oxy sensors on here but some people say we need them, others say we don't... The vehicle originally had them so, do I need them or not?

The other one is the VSS - some say I need it, others day I don't. I am using a surf Gearbox so unless we get another signal it won't be easy. Is it necessary?

I need to gound the wire (510ohm) to tell it is is a manual?

Does the tune select make any difference if I don't use the oxy sensors? The vehicle is Japan spec. (motor was in an imported disco which was rolled)
There is no catalytic conv.

The vehicle will be road driven.

Cheers, Glen

[chimpboy]

A bit of info here, use it with caution: http://www.britishv8.org/Articles/Rover-14CUX-EFI.htm

Plus some links at the bottom.

You don't need the VSS or the O2 sensors. Of the two the O2 sensors are probably more desirable but you can add them later if you want them.

Philip A is very good on these ECUs, hopefully he will chime in with better answers for you.

[Philip A]

The VSS does a couple of things

1 Injector shut off at minimum TPS and revs over 1500RPM.ie overrun shut off

2 idle up on the stepper when moving. I think this is to prevent stall on stopping, and even all manuals I have driven with injection do this. I don't think grounding the wire is necessary or desirable.

I would leave it insulated. There are lots of injection installers around who should have a solution for the VSS eg a cruise control type sensor on the driveshaft.

The 02 sensors give closed loop lambda at all times except WOT, or maybe 3/4 throttle but I have never been able to ascertain EXACTLY when it goes open loop. You have to have a different tune resistor without the o2 sensors.
I guess the main advantage to me is that you always run at Lambda whereas an old injection may be too rich ( more common) or lean. The closed loop automatically compensates.

Regards Philip A

[Philip A]

The following information on Tune Resistors is based on Rover service literature.

Visual inspection of wire color codes will allow you to quickly differentiate between resistors.
White 3900 Ohms USA and European vehicles with catalytic converters
Green 470 Ohms UK and European vehicles without catalytic converters
Yellow 910 Ohms Saudi vehicles (without catalytic converters.)
Red 180 Ohms Australia and "the rest of the world."

You may find the Saudi one is better than the Oz one as the Oz one requires a lean idle, but I do not know for sure. If it is a High compression engine maybe the UK and European without may be the go. Green

"With catalytic converters " means with o2 sensors.

The main difference with UK Vs rest of world is High compression at 9.35:1 Vs low comp 8.13:1 for Australia.


Regards Philip A

[NJV6]

Thanks chaps.

I will put the O2 Sensors in when I do the exhaust then.

I will run it and access whether I need the VSS (ie stalling etc)

Japan motors are high comp 9.35. I think it is a white wire, is it the one with a blue connector in the loom about half way from ECU to main plug, shrink sealed with the resistor inside it?

You mention Philip, about not grounding the wire with the 510 resistor. Why is this? I understand it was what was used by the ECU to "tell" it that it was a manual vehicle.

Thanks, Glen

[Philip A]

I am only working from intuition.

In my experience , all modern manuals I have driven do the same thing as autos.

They all have injector cutoff at 1500RPM on overrun.

If the VSS was grounded then the ECU has no way of knowing that the car is moving, so it would be impossible to have overrun shutoff.

So in my logic Injector cutoff = TPS< .49 volts, VSS signal present, RPM>1500RPM.

Unless Land Rover is different to every other injected car made , it does not compute.

I do not think on a 14CUX that the ECU knows or cares whether it is auto or manual as the auto is throttle controlled by kickdown cable.

Regards Philip A