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robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

Annoying Fault i cant Diagnose

Does anyone know what could be causeing this fault:

When i press the accelerator pedal to the floor, it seems to change how the pedal responded. You have to push it further to get the same output from the engine.Its only when you give it full throttle and then it stays the same after until the restart.

Its almost like it goes into the low range throttle mode. It happens in any gear, at any revs etc, and turning the off resets it back to normal again.

I could drive for any amount of time without hitting full throttle and it wouldnt have this problem.

I initially thought it was putting it into a limp mode as i thought it did it when it boosts (as this was when i gave it full throttle to over take or something), but i have also now noticed it does it at very low revs even before the boost kicks in.

I have asked my indy about it a few times, but he keeps saying it pulls up no fault codes. I have even taken him out with his computers connected, but he says it looks normal even though i can feel it isnt.

I have had the problem for a while, and have never got to the bottom of it, but im thinking of getting a remap in the new year, so want to running properly before i do.

Its very annoying as my garage cant find the problem.

Any ideas welcomed... Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

7th Dec 2011 12:13pm

Grockle

Member Since: 24 Nov 2008
Location: Peak District National Park
Posts: 2266

2008 Defender 90 Puma 2.4 XS CSW Tonga Green

check the crank postion sensor 2.4 90 XS
1968 1/32 scale Britains 109 Pick up.

7th Dec 2011 12:15pm

Zinke

Member Since: 27 Jan 2009
Location: Scunthorpe
Posts: 670

Not any help to you but mine does exactly the same thing. And ive heard of a few other people with the same problem. Hopefully gary from Alive will be along shortly to explain

Pete.

7th Dec 2011 12:21pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

Thanks all for the responses so far. Yeah i have also heard of others doing it too, but never got a definative answer. Its bloody annoying

Grockle wrote:
check the crank postion sensor

Why would that make a difference? It runs fine Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

7th Dec 2011 12:30pm

Martin
Site Admin

Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6611

2015 Defender 90 Puma 2.2 XS CSW Montalcino Red

Does the response change when you put the transfer box in low? Try it in neutral and not moving.

1988 90 Td5 NAS soft top

2015 D90 XS SW

7th Dec 2011 12:41pm

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559

Have you checked the waste gate on the turbo ?
This can give a loss of power and it will reset when ignition off then on
Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88â€ 2A 200tdi
2002 110 Hardtop

7th Dec 2011 1:19pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

Martin wrote:
Does the response change when you put the transfer box in low? Try it in neutral and not moving.

Yeah does change as expected when in low range, maybe i will put it into low range, full throttle then back into high and see if its changed back to what it should be like or stayed in low range mode.

Its also hard to tell without moving if its changed or not Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

Last edited by robpenrose on 7th Dec 2011 1:36pm. Edited 1 time in total

7th Dec 2011 1:34pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

derbywill wrote:
Have you checked the waste gate on the turbo ?
This can give a loss of power and it will reset when ignition off then on
Will

But it does it even if the turbo doesnt boost. Doesnt the waste gate only open on full boost?? Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

7th Dec 2011 1:35pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

To update:

Just ran a couple of tests:

Put in in low range, stationary & push the accelerator to the floor, revs only go up a bit, back into high range and drive off and it seems like it hasn't come out of low range throttle response, showing same simptoms as I was experiencing before.

Next test: (restart engine to cancel symptoms)

In high range, stationary & push the accelerator to the floor, revs go up a little, drive off and it's gone into the low range type throttle response again.

By low range throttle response, I basically mean you need to push the throttle down further to extract the same amount as power as when it's working correctly.

So the problem happens in high and low range (although doesn't appear noticeable in low range, but is when high is selected again), moving or stationary, at full engine load/boost or low revs and no boost, or in neutral/gear.

Anyone anymore the wiser after these findings?? Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

7th Dec 2011 6:18pm

twopoint6khz

Member Since: 18 Aug 2011
Location: North Lakes
Posts: 654

Sounds like the high/low switch on the transfer lever may be sticking in low? I think low is closed. I imagine it'd be easy to see if you whip the centre seat/cubby box out, lift the centre panel and have a look down at the transmission.

7th Dec 2011 6:20pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

I don't think it's linked to that switch, as it does it when your in high and don't touch low.

The only thing in common with everything is pushing the throttle to the floor, then the fault occurs and doesn't go until the engine is switched off. Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

7th Dec 2011 6:50pm

landy andy

Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5729

2006 Defender 110 Td5 USW Zermatt Silver

I think you need new potentiometer, accelerator pedal.

Andy

7th Dec 2011 7:13pm

Lorryman100

Member Since: 01 Oct 2010
Location: Here
Posts: 2686

It does sound as if there is a problem with the pedal potentiometer whether it is at fault or the wiring harness is damaged. When the garage hooked up his diagnostics and you went for a run did he notice if the D% and E% readings corresponded with the pedal position? Also try a good covering of AC-50 on the pedal to disperse any moisture and give the plug a clean with electrical contact cleaner incase of mineralization contamination.

7th Dec 2011 9:54pm

robpenrose

Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338

I thought about a new pedal, the annoying thing is they are about £100, so i dont want to buy one if it wont fix it.

Would it be possible to trace the harnesws back without completly ripping the car apart, or get any other form of diagnostic to check it, or the pedal seperatly?

Im not sure on the D% and E% Lorryman100, the mechanic just said it looked normal, although i do remember him saying something look slightly low, but not out of tolerance. It was back in August when i had it done!!

Dont suppose anyone has a spare pedal that they know works that i could use to check??

All the help and information much appreciated. Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

8th Dec 2011 9:35am

bell-auto-services

Member Since: 08 Jul 2007
Location: North Yorkshire
Posts: 2232

2013 Defender 110 Puma 2.2 USW Orkney Grey

Im not fully sure I understand your description of the fault but they are prone to the pedal wires chafing through inside the loom casing that is like a corrugated casing, this is more noticable when the car is wet for obvious reasons.

I would also be testing the fuel pressure at the head regulator and you should see 4 bar at all times.

Pete

8th Dec 2011 9:13pm

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