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

Yesterday my '93 +8 cut out on the start line at Scammonden, and resisted all efforts to get it going, in spite of having a spark and the fuel pump ticking when the ignition was switched on.

Today I plugged in RoverGauge, and noted that the MIL light was red. However, when I viewed the error codes listing, no error code was highlighted. Nevertheless, I cleared the error codes (I have no idea why!), turned the ignition off, turned it on again, and lo and behold, the car started. I repeated the stop/start/clear code process several times, and the MIL light remained red each time I reconnected RoverGauge. Every time, the error code highlighted was 69 "Neutral gear selector switch", which I suspect relates in some way to automatics, and certainly the car started ran happily with that error present. The ECU has a Tornado chip.

Has anybody experienced a similar cutting out and refusing to run issue, and did you get to the bottom of it?

All comments/suggestions gratefully received!

Dave

Dave

I am unable to pinpoint your exact problem from the diagnosis, perhaps some one with more diagnostic experience than I (Mike Smith, Teknome on here ? ) will be able to do so , but what I do have is the Rover 14CUX fuel injection manual which I can send to you.

It is a large file (6.2MB) even as a pdf, so better sent as an email attachment rather post here. If you pm me with your email address I send it today.

Tornado chips can be very sensitive I have had one installed in my 94 +8 for over 14 years and the Check Engine light always comes on and showing fault code 48. I also have a non chipped 14CUX ECU which when installed does not activate the Check Engine light and shows no fault codes. The engine has run perfectly with the Check Engine light on, for rallies I remove the bulb as there are enough gauges to tell me if there is an engine issue. I would start by doing a complete reboot of the ECU i.e. disconnecting power to it for 30 minutes and then see if the issues reoccurs.

When I had a similar problem on my 1998 Hotwire Plus 8, it was the Lucas coil, It would start and run fine then all of a sudden die.
Fitted a Bosch coil and had no problems after that.

Keith

The 14CUX is prone to producing erroneous error flags. I have modified the code to enable the MIL light, and wired in a MIL light, to my +8, and it comes on randomly with no actual error code being stored. My understanding is that the function (MIL light) was disabled in the 14CUX used in the Discovery, probably because of the tendency to set the MIL light flag for no good reason. I often found that when the MIL light comes on, it clears with ignition off and back on again. Whereas a hard error stays, and has to be cleared with a reader, or the red key.

The neutral error is code 69 and basically prevents the vehicle from starting unless the gearbox is in neutral (or park ?). The signal comes in on pin 34 of the ECU (possibly an orange/black wire). I would expect that the signal wire would be grounded when in neutral, maybe via a resistor. Probably inhibits the fueling when not in neutral.

The Discovery wiring diagram shows an orange/black wire connection from pin 34 to a resistor that goes to ground in the case of a manual transmission (so always in neutral).

As you had a spark, and the initial running of the fuel pump, maybe the problem was that the injectors were not enabled, either due to this neutral switch issue, or the absence of the signal from the coil to the ECU, which comes via a black, rectangular, resistor that is in the wiring loom very close to the coil, you may actually find two resistors.

Probably a good idea to check the resistors near to the coil (you may find them wrapped in tape) and make sure the connections are good, and check grounding points from the loom to the body.

I had read somewhere that Mark Adams had disabled some of the unused diagnostics, don't know if he will have disabled this 'neutral' check, I will see if I can find the reference

When you fitted the Tornado Chip, did you also replace the amplifier with the RIP amplifier?
The original amplifier is rubbish, I’ve known many that’s gone wrong and can give the faults you describe.

I should have explained that the signal from the coil to the ECU lets the ECU know that the engine is running and the ECU uses that signal to determine when to fire the injectors, it is a bit crude and the ECU just fires one bank of injectors, and then the other bank, alternating them. So absence of the signal from the coil will prevent fueling. However the only bit of evidence does point to the 'neutral gear' flag, I am not sure where the resistor for that signal is located, probably in the loom somewhere, there are a few resistors in the loom behind the dash, one of them will be the tune resistor to tell the ECU if the car has a catalyst.

I have some rather different experience to yours then.

I swapped the amplifier to the RPI one, and experienced several bouts of trouble, reverting back to the Rover "standard" unit cured them all. All of the competition +8s with 14CUX in the Aero Racing Challenge use the standard system.

Funny how things go, I went through several amplifiers in the first few months of owning the Plus 8, then fitted the RPI amplifier which is still on the car 20 odd years later.

Is this another erroneous error flag?
Took the +8 for it's first post lockdown spin. After 3 miles it cut out, freewheeling to a halt. It started first time on the key and has run ok since. The RoverGauge error code was 21 with the message 'Tune select resistor out of range.'. It was running on tune 5, which is the UK 3.9 with cat which is the normal tune. I reset it and no trouble since.