TD5 No Throttle but engine running? Help!

Had started to exeperience what felt like a flat spot on acceleration, getting more frequent and prgressivly worse over last 3 journeys, (checked and clean MAF and MAP all good and orginal LR parts)

Today lost all throttle control and had Engine MIL light on.

Lucky i was only .5 mils from home so managed to get home on tickover / anti stall,
Once home I cycled ignition and restarted engine all good.

No fault codes stored ( using a delphi ISS) other than some randoms that relate to items i dont have ( ABS, Aircon, etc)

On sunday i was feathering the throttle trying to identify when it would happen, and certainly felt like a flat spot in the middle of the throttle which lead me to think pontentiomter issues.

i did some tests via the Delphi, and got what think are normal readings fromt he throttle pot in terms of rise and fall.
The joys of intermitant faults
Does this sound like a throttle pot going bad? or somthing else?
if ecu loses signal from throttle pot will it throw on MIL light and ignore throttle? Anti stall worked fine as i have avery steep driveway for 100 yards it climbed it just fine @sierrafery

Current thinking,
a) connection incosistancy form throttle pot to ecu
b) ECU signal generator or supply voltage issues to throttle pot
c) throttle pot on its way out
d) somthing else

driver demand on all three seems ok
Track 1, and two are more or less mirroring and rising and falling in unison, in real time. track three seems to remain constant.

chaffing wire, perhaps,? ho hum
So I dont mind getting a new throttle pot, but they not cheap so be good to hear what other think?


then again of course its October the season for all landys to have a strop and sulk ahead of the winter lol

i hear direct wire to the pot from ecu may be the way fwd anyone know the wires?

Continuity test all wires end to end from throttle potentiometer, should be o ohms resistance or close to

not looked at wiring diagram but if there an earth also check that

I’m sure somewhere ther will be a pin out test for the potentiometer to check resistance readings too

haza88 said:

Continuity test all wires end to end from throttle potentiometer, should be o ohms resistance or close to

not looked at wiring diagram but if there an earth also check that

I’m sure somewhere ther will be a pin out test for the potentiometer to check resistance readings too

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done that all fine

If you have checked the readings on the tps via resistance readings from top of pedal to bottom via multi metre u no it’s not that then , can’t be wiring as you checked them via multi metre and , can’t be earths as they’re ok as well via multi metre , may time to get ecu checked

Another thought train may be worth checking wiring to the injectors and diesel pump , pedal and ecu may be working fine but signal may not be going forward to the fuel pump injectors etc

haza88 said:

Another thought train may be worth checking wiring to the injectors and diesel pump , pedal and ecu may be working fine but signal may not be going forward to the fuel pump injectors etc

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i think its wiring, intermittent, knocking up a by pass loom to pot ans testing this weekend, cant diagnose until its in fault etc

I'm a bit late to this conversation, but I had this problem with my TD5 some years ago. Wouldn't run any faster than tickover and had a yellow engine warning light. It turned out to be the wiring between the accelerator and the ECU. My fault was intermittent for a while and wouldn't show up for the garage, but would occur with me. I was assured by many that it was the fuel pump, of course.

I had this on my D2 TD5 and it was caused by low battery voltage, engine started no problem but gave low volt's to ECU.

FIXED!
in the end i ran a fresh jumper from throttle pot to ecu, 7 into 5 wires, removed ecu female pins and crimped on new so stiill have old wiring, no cable cutting etc.
Got a new throttle pot switch plug with tails, all done test drive fine. pics n details on my build thread,
cheers @haza88 for you thoughts, appreciated!

had no idea this was a td5 'thing' add to the list of common faults then!
When i get time i will test each wire and have a rummage and wiggle about with the loom, another reason i did not chop into wires, so still have the orginal plug tucked up under dash, and the ecu tails intact, had to use long nose pliers cos i could not find my econoseal crimper die, its been a while since i did them with pliers.....still got it though!!

Glad you got it sorted , greening wire/ partial broken wire or oil in loom ? Be interested to see what you find

haza88 said:

Glad you got it sorted , greening wire/ partial broken wire or oil in loom ? Be interested to see what you find

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No oil in loom, fitted a good three part seal on injector harness, cant remember where it got it from, but been in for 5 yrs now not a drop passes from rocker cover.

It will be a wire breakdown, or abrasion causing short / voltage drop etc..

My guess is either within 30 cm of pedal, its clamped tight to bulkhead, behind dash or loom from MAF behind engine.
Constant shaking after a while the plastic becomes brittle pin holes then the wire corrodes and fractures.

I'm glad you solved it. It sounded very like my wiring loom problem. Land Rover seem to have had a batch of wire with some peculiar characteristics in the early 2000s. The conductors are stiff and brittle and the insulation tends to go crisp and flake away. Eventually, I got a whole new red plug engine loom. It felt very different - soft and supple, like a proper car wiring loom. It's been OK for seven years now, and I hope it'll last a bit longer. The main wiring looms are a bit of a blind spot when it comes to fault diagnosis. Everybody says it must be the fuel pump, or the potentiometer unit, or the fuel filter and so on. But the wiring looms seem to give quite a bit of trouble, especially as they age.

Post pics of the fault when you get round to finding it I love a good wire hunt spend my days doing it on tractors

haza88 said:

Post pics of the fault when you get round to finding it I love a good wire hunt spend my days doing it on tractors

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i can find the right loom / run then can calulate where using mafs / rithmotic and head scratch lol
I expect it will caused by abrasion, or vibration constant flexing ( like door wires) after a while the copper just gives up!