Thread: Defender TD5 Power Loss, No throttle

Originally Posted by Kelly928

Hi All,

I have read nearly every post on this topic and related topics at least twice. I have spent the last 4 weeks trying to sort the problem out myself with the help of experiences here. I believe I may have narrowed it down to TPS and need confirmation. Here are the details,

Vehicle: 2003 Defender TD5

Symptoms:

Sudden drop/loss of power on acceleration (mainly 3rd and 4th gear) and also when coasting. Some days worse than others, random occurences. Severity varies. Occurs under load and also no load.

Inspected:

- Injector harness and loom both ends. Oil found at both ends. Cleaned and flushed everything.
- Throttle. Inspected plug and wires that goes into the pedal position sensor?. Visually OK. Plug at ECU end was clean and wires intact.
- MAF, AAP sensor. Replaced MAF (cause I broke it cleaning it, $235), cleaned AAP sensor, all related wires intact.
- Air filter box and related Snorkel plumbing clean.
- MAP, very gunky! Cleaned.
- Intercooler hoses. Turbo/intercooler hoses soft but not delaminated, relatively clean internally and not split. Intercooler/EGR hose bit oily internally but otherwise good. Silicone hoses on the way.
- Wastegate. Moves freely
- EGR valve. Bit gunky but not sticking. Cleaned.
- Inertia switch and wiring. Tested and operating normally.
- Fuel pressure regulator. No leaking diesel.
- Fuel filter. Not dirty but replaced anyway.
- Earth points. All secure and intact.
- Fuses. All secure and intact.

Today on way home coasting on freeway (~90km/hr) power drop outs became increasingly severe then all of a sudden no throttle, engine into idle speed, engine light on (first time I have seen it light up, except on startup), I **** my pants and had to manuver the fender across 3 lanes in peak hour with no throttle.

I turned off ignition and started back up. Engine light now off and can drive but very slowly bout 60km/hr and still getting power drop outs. Have to be very gentle with throttle.

2 minutes later no throttle, engine idle......etc. Pulled over turned engine off and on again. Engine light off and I drove real slow and managed to get home. Touch and go all the way.

The engine starts and idles normally and in neutral I can use throttle and rev slow or hard with no drop outs and plenty of smooth power.

So considering all of the above I believe I have a problem with either throttle position sensor or the throttle harness/wiring somewhere between the pedal and the ECU plug. And it is some how evident when in gear for some reason.

Can someone please confirm my conclusion. I have come so far and learnt so much along the way I want to finish this.

If it is the throttle harness/wiring and or TPS is it a cheap and relatively easy fix?

Any advise, info or experiences very welcome. Have taken coming Mon and Tues off to have a long weekend camping too.

Thanks
Kelly

Almost certainly the throttle potentiometer or associated wiring, as that is the most common cause of limp mode apart from overboost, but that usually won't illuminate check engine lamp in Defenders or manual D2's, just cause a jerk and 'misfire' under hard acceleration. The throttle potentiometer (Pedal assembly) is easy to replace, AFAIR about $270 or so? May be a bit out in my guestimate, haven't bought one for at least a year now.

JC

I've just replaced the TPS on my 2003 manual TD5 D2 because it developed a dead spot just off idle (and turned-on the check engine light) every time light throttle was used one day whilst driving in Canberra Friday afternoon peak-hour traffic, then again a few weeks later whilst taking off from a railway crossing.

It was very consistent and only occurred at the one spot, so no problem if the throttle was quickly pressed past it from idle. There was also no oil in the engine loom anywhere.

It cost approx $165 from a well-known Sydney importer.

you have eny chance of geting t4 on it an geting fualt codes, i had a simalor sorta of thing but would loose power and then dy compleatly,,, found to be top side switch failed in engine ecu, new ecu was the fix,, to this day still dont no what mad the ecu pack its self praying it dont hapen agen

I read a post by Blknight on using a multimeter (set on resistance) across the TPS module and depressing the pedal to check for funny resistance readings. I assume on a 2003 Defender I need to put the multimeter probes into the positions on the TPS module where the two purple/white wires (to which the 5V potential is applied, RAVE CD) would go into. Dont really know what I am doing with this test but will try this tonite.

Is there a way of checking (using multimeter?) the 2 black and yellow earth wires for earthing problem?

I did consider ECU actually causing the problems but hope not at this stage.

Just got the first quote for pedal assembly (3 position) of $280.

Will update on progress.

As regards fault code descriptions, it should come up as a 'driver demand error'

JC

Originally Posted by Kelly928

I read a post by Blknight on using a multimeter (set on resistance) across the TPS module and depressing the pedal to check for funny resistance readings. I assume on a 2003 Defender I need to put the multimeter probes into the positions on the TPS module where the two purple/white wires (to which the 5V potential is applied, RAVE CD) would go into. Dont really know what I am doing with this test but will try this tonite.

Is there a way of checking (using multimeter?) the 2 black and yellow earth wires for earthing problem?

I did consider ECU actually causing the problems but hope not at this stage.

Just got the first quote for pedal assembly (3 position) of $280.

Will update on progress.

I'm just down in Carlton and have a Nanocom, and have no problem using a multimeter, you are welcome to come down at any reasonable time and we can check it out. Possibly even swap my TPS into yours for a day or two to see if that fixes it. PM me for my number.

Cheers,
Fraser

Hi Kelly

It could Be the TPS but the loss of power could also be a lack of fuel I'm betting its the fuel pump you may need to check the fuel pressure
cheers mark

OK so I took up Frasers kind offer (thanks mate) and he hooked me up to Nanocom. ECU had logged 2 x 'Driver demand' errors which does confirm TPS or related wiring so I will replace with new TPS and monitor.

Strangely enough on the way over to Fraser I drove it hard but could not replicate....??

ECU had also logged 'Injector 2' intermittent fault which most likely would have been a result of the oil in harness. After clearing this fault it did not return so I guess cleaning the harness helped.

Fuel pump and related sensors did not log faults and has not been making strange noises so will assume this part is OK.

Fingers crossed. Will update.