Rover V8 ECU interchangeability

[Harleyboy]

Morning,

I have a 91 Range Rover 3.9 V8 with suspected ECU issues. The ECU has a part number PRC9061 with a date code of 2391.

I have a question - will any 14CUX ECU work in my car? I'm looking to borrow another ECU to confirm or eliminate the source of the issue. A friend offered to loan me his which is a CAT equipped 93 soft dash model. I was worried my car could damage his ECU and that it would be set up differently and therefore wouldn't be right for mine.

Testing and repair isn't cheap so am looking for a test route first. Any help appreciated.

Thanks

[100SRV]

The "tune resistor" determines whether or not the vehicle is equipped with catalytic converters and this is part of the vehicle EFi harness, not integral to the ECU.

Unplugging one 14CUX ECU and plugging in a different one shouldn't cause you any problems.

What are the failure symptoms?

[Harleyboy]

thanks - good to know. Looks like trying my friends soft dash ECU should work.

first symptoms which have been present for some time were occasional but momentary cutting out and some stalling when manoeuvring. I ignored this as its not my daily drive. This progressed to occasional misfire and then to permanent.

I have thus far changed distributor, plugs, leads and coil. Seems to have cured the misfire but there is no power under load. I took it to a local tuner who suggested I try a replacement air flow meter (did that, no change) or the ECU. ECU has been suggested a number of times, hence me now wanting confirm or eliminate this as the issue. I'm not keen on buying an Ebay unit as this could also be faulty so would rather repair mine if I can confirm its the issue.

[Steve_D]

As has been said the ECU has about 5 maps in it which are selected by a different resistor in the vehicle loom so switching to another 14CUX ECU will be fine (caveat TVR or Morgan ECUs which may have a different chip but should still be OK to prove a dead ECU).

From your description the ignition system is more likely the culprit and in no way is controlled by the ECU. Ignition amp is a favourite.

For the future it is worth investing in RoverGauge (cable & software £35 in TVR classifieds) It will show what is happening in the ECU and can prove/disprove sensor faults etc.

Steve

[paintman]

http://www.rangerovers.net/repairdetails/classic/e...

[Harleyboy]

Steve_D said:

As has been said the ECU has about 5 maps in it which are selected by a different resistor in the vehicle loom so switching to another 14CUX ECU will be fine (caveat TVR or Morgan ECUs which may have a different chip but should still be OK to prove a dead ECU).

From your description the ignition system is more likely the culprit and in no way is controlled by the ECU. Ignition amp is a favourite.

For the future it is worth investing in RoverGauge (cable & software £35 in TVR classifieds) It will show what is happening in the ECU and can prove/disprove sensor faults etc.

Steve

Hi, that was one of my early thoughts too, hence changing the distributor and amplifier (for new one, not used part) as well as coil and leads. It has cured the misfire but I have the new issue of no power under load. I'm getting frustrated with it all now!

[Trevor450]

A friend of mine had this with a P38. I realise they use different ECUs, but the throttle potentiometer can cause loss of power under load.

[Steve_D]

Trevor450 said:

A friend of mine had this with a P38. I realise they use different ECUs, but the throttle potentiometer can cause loss of power under load.

This and any other sensor issues is why I suggested RoverGauge software.
You can see on screen what each sensor is doing.
Have a read here.... http://www.g33.co.uk/pages/technical_fuel_injectio...

Steve

[Trevor450]

Steve_D said:

This and any other sensor issues is why I suggested RoverGauge software.
You can see on screen what each sensor is doing.
Have a read here.... http://www.g33.co.uk/pages/technical_fuel_injectio...

Steve

Indeed, I’ve got it for my Chimaera.

[Steve_D]

Trevor450 said:

Steve_D said:

This and any other sensor issues is why I suggested RoverGauge software.
You can see on screen what each sensor is doing.
Have a read here.... http://www.g33.co.uk/pages/technical_fuel_injectio...

Steve

Indeed, I’ve got it for my Chimaera.

Chimaeras are my day job.

Steve

[Harleyboy]

Steve_D said:

Chimaeras are my day job.

Steve

Thanks for the info. Rover gauge sounds useful but i have to say i find it all really daunting! I’m not technically minded nor great with software but it is probsbly worth a go. I’d really like to find someone in north wiltshire that could take a look as i dont have a lot of time to do this sort of stuff.

I really appreciate all the responses though.

Cheers

[Harleyboy]

So, i borrowed an ECU and there was no change. Will look at getting the software and also try find someone who can sort it locally.

[blitzracing]

The ECU may have a fault code logged if you have a faulty or intermittent sensor, but the ECU warning light is not enabled on UK sold cars. A nasty master plan so you have to go to the dealer with diagnostics to get the error codes!. Dont get too worried about the technical complexities of RoverGauge, you can start with the simple stuff like fault codes, and checking the various sensors are in range. Fault finding without good data is almost impossible. RoverGauge cable kits can be found under TVR parts here on PH. Happy to help with diagnosing faults if we have the data, or Im near Hungerford if you get really stuck.

[Harleyboy]

Rovergauge and cable on their way! Away for a week but will report back asap