Some more stuff to look into
Try testing the throttle position sensor.
The voltages can be measured at the ECM the Black plug C0658
Using just a multimeter.
ACCEL. WAY 1(V) - about 0.3V with the pedal released, about 4.7V with pedal to the maximum position
C0658-12- white/green - throttle pedal sensor 1 0-5v input
This shows the output voltage from driver throttle pedal potentiometer 1 as read by the TD5 ECU.
The voltage reading increases as the throttle pedal is depressed.
A fault will be recorded if the sum of the voltages of throttle 1 and throttle 2 do not add up to the throttle supply voltage + or - 10%
ACCEL. WAY 2(V) - about 4.7V with the pedal released, about 0.3V
C0658-36-white/silver-throttle pedal sensor2 analogue 5-0v input (C787-K)
Your car would not have had this pedal type fitted as new but could have been retro fitted.
ACCEL. WAY 3(V) – this track must have values very near to the second track.
C0658-20- red/green - throttle pedal sensor 3 analog 0-5v in(787- C)
(only for EU3 engines)
This shows the output voltage from driver throttle pedal potentiometer 3 as read by the TD5 ECU.
The 3 Track Throttle Potentiometer configuration is not used on all vehicles and was introduced at VIN Number YA288371 on a Discovery and 1A605426 on a Defender. The selection may be configured in the settings section.
ACCEL. SUPPLY(V) – this value must stay between 4.9 a 5.1
C0658-14-white/purple -throttle pedal supply (C0787- B) - 5v input
As above - white/purple - pedal connector (C0787-J) - supply 5v input
This shows the regulated supply voltage for the driver throttle pedal potentiometers.
The sum of the voltages from driver throttle pots 1 and 2 at any throttle position must add up to within 10% of this voltage or a fault will be recorded.
This should test the pedals outputs to ECM.
If this tests ok the next thing you will have to do is get the car hooked up to nanocom or other test system that can give you live data.
If you have a faulty ECM you will need to use a nanocom or other tester and a known good ECM.
You will have to remove cam cover write down the injector
codes for each cylinder.
(IMPORTANT If you are using a ECM from another car you will also have to record its injector codes so it can be recoded after testing.)
Fit the known good ECU hook up nanocom and code the ECM to suit your injectors.
Also note you must use the correct ECM for your car
here's a list of what will work or not work.
It MUST be an auto ECM
NNNs are remapable through OBD port the MSBs are not you need to fit a chip.
AUTO
MSB101192 1 ELECTRONIC CONTROL UNIT ENGINE, AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
MSB101193 1 ELECTRONIC CONTROL UNIT ENGINE, AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
MSB101340 1 ELECTRONIC CONTROL UNIT ENGINE, AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
Remapable
NNN000130_USE 1 ELECTRONIC CONTROL UNIT ENGINE, AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
NNN500030 1 ELECTRONIC CONTROL UNIT ENGINE, AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
LR006301 1 ELECTRONIC CONTROL UNIT ENGINE, EXCHANGE PART (RE-MANUFACTURED) AUTOMATIC TRANSMISSION, '(+)"EUROPE/J"'
MSB101260 1 ELECTRONIC CONTROL UNIT ENGINE, (AUTOMATIC TRANSMISSION, '(-)"J"' OR AUTOMATIC TRANSMISSION, '(-)"EUROPE"')
MSB101261 1 ELECTRONIC CONTROL UNIT ENGINE, (AUTOMATIC TRANSMISSION, '(-)"J"' OR AUTOMATIC TRANSMISSION, '(-)"EUROPE"')
MSB101350 1 ELECTRONIC CONTROL UNIT ENGINE, (AUTOMATIC TRANSMISSION, '(-)"J"' OR AUTOMATIC TRANSMISSION, '(-)"EUROPE"')
MSB000130 1 ELECTRONIC CONTROL UNIT ENGINE, (AUTOMATIC TRANSMISSION, '(-)"J"' OR AUTOMATIC TRANSMISSION, '(-)"EUROPE"')
MSB500030 1 ELECTRONIC CONTROL UNIT ENGINE, (AUTOMATIC TRANSMISSION, '(-)"J"' OR AUTOMATIC TRANSMISSION, '(-)"EUROPE"')
MANUAL these will not be of any use.
MSB101183 1 ELECTRONIC CONTROL UNIT ENGINE, MANUAL TRANSMISSION
MSB101184 1 ELECTRONIC CONTROL UNIT ENGINE, MANUAL TRANSMISSION
MSB101330 1 ELECTRONIC CONTROL UNIT ENGINE, MANUAL TRANSMISSION
NNN000120 1 ELECTRONIC CONTROL UNIT ENGINE, MANUAL TRANSMISSION
NNN500020 1 ELECTRONIC CONTROL UNIT ENGINE, COOLED EGR, CHECK FOR SERVICE EXCHANGE VERSION, MANUAL TRANSMISSION
LR006328 1 ELECTRONIC CONTROL UNIT ENGINE, EXCHANGE PART (RE-MANUFACTURED), COOLED EGR, MANUAL TRANSMISSION
NNN500250 1 ELECTRONIC CONTROL UNIT ENGINE, NON COOLED EGR, MANUAL TRANSMISSION
I can understand that you are disheartened with the car trying to diagnose a running car is difficult enough let alone one that has been mucked about with then abandoned.