Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Lucas 14CUX help/advice, please

Looking back at the "Neutral gear selector switch" error, which I believe would inhibit fueling at startup if the input (with an auto box) showed the gearbox was not in neutral. That error flag would not be the cause of the engine cutting out, as it would be normal that the gearbox is not in neutral (i.e in drive). So I think that there is an initial cause of the loss of power, and maybe that also causes a glitch that upsets the routine that is scanning for errors.

The only common point between the 'neutral' signal and the tune resistor signal is that they both reference to the chassis ground. For the 'neutral' signal there is a resistor from pin 34 to ground, and for tune resistor it is between pins 27 and 5, where pin 27 also goes to ground.

Probably not relevant, but when you don't have the RoverGauge plugged in do you insert the grounding plug into the diagnostic socket. That grounds pin 18 of the ECU.

When the engine cuts out, if left in gear with the engine being turned over as it coasts, does the rev counter still display the engine speed, if yes, then the primary ignition circuit is still working, if no then points to a problem with the primary circuit.

When it cutout, did it start straight away, or did the engine (and components) have time to cool down before restarting. Normally the coil and ignition amplifiers tend to fail with heat.

A problem I had with my Plus 8 that plagued me for some years. It would be happy for days and months, then just run a bit rough and stop. Sometimes it started immediately, sometimes it refused to start, but then started when it had tried my patience. A few years ago I was in Cornwall, and it refused to start. I decided to check the gap between the pick up coil and reluctor in the distributor, I judged that a bit of card was the correct thickness, I wiped the card through the gap, it seemed correct, put everything back and it started and I didn't get another issue. I didn't leave it there and did replace components, but that's a long story of the current state of poor quality components that are sold as OEM quality, and items sold under Lucas part numbers that are different in build to the Lucas item, it is certainly a jungle out there.

Hi Mike. Working backwards, my +8 restarted immediately so the cutout was not due to coil problems etc. Just had a new coil anyway. I didn't notice the rev counter, I was busy making sure the car behind didn't run into me! However, I might have left the diagnostic socket cover off. The socket is in an awkward position and the connecting wire is a tad short making the cover difficult to handle. Do you feel that there may be more erroneous error codes flagged up if the cover is left off?

The diagnostic socket ;cover' grounds pin 18 which is the diagnostic serial port input. When you use the diagnostic cable from PC to ECU the diagnostic cable ECU end plug has a 400 ohm resistor from the ECU input port to ground. So I think that there was concern to reduce any electrical noise at the input to the ECU. I assume that noise on the diagnostic input mat cause the ECU to think there is data at the input, which could cause it to spend processing time, and maybe if the ECU processor gets stressed it is apt to cause glitches.



Many years ago I saw a reference stating that there was an internal Rover document with a detailed technical description of the 14CUX, I think it was on controlled circulation in the Rover group and I haven't seen a copy out in the wild. Most of the detailed information tends to be from reverse engineering by the TVR guys.

I thought I'd give an update of where I'd got to with my car, and answer a couple of questions that arose.

Firstly, thanks for everybody's comments and suggestions - as usual, TM is a fount of knowledge. I also spoke to Brian Gateson at Techniques.

Courtesy of the previous owner, my car came already fitted with the Tornado chip, a Mallory distributor and a Bosch coil (so there is no ignition amplifier). Up until now it has been as reliable as a pet rock throughout my 4 years of ownership.

This week I rebooted the ECU, and went through as many earthing points as I could find (back of the left hand cylinder head, bulkhead etc). The bulkhead earthing point (which I appreciate may or may not be relevant to the injection system) is, on my car, located immediate below the bonnet hinge - so you can guess the state it was in. I cleaned up both the inside and outside of the bulkhead, sealed the bolt head to prevent further water ingress, and Hammerited the area. The injection relays look to be the originals (thus 28 years old), so new Bosch items are on order, and will be fitted at the first opportunity.

I can't replicate the fault that occurred, and I had to take the car to Barnard Castle yesterday (hard top fitting, not Dominic Cummings eye test), so I loaded up with laptop, tow rope, spare relay of unknown vintage from my "stores" etc etc, and kept an eye out for convenient laybys to break down in. Needless to say, the car did not miss a beat, so whether it's fixed or not remains to be seen....

Dave