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amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Weird drop in power when flat out

I have a 1999 tf5 defender that has done 192000 miles. It has decat pipe , tp exhaust and a remapped ecu.

Recently I have a strange problem that means that I can accelerate as quickly as I like through the gears n full throttle. The car performs faultlessly and accelerates very quickly, as it should. However when up to speed in 5th gear eg on motorway cruising at 70mph if you floor it the car begins to accelerate and then suddenly the power goes and the car reduces its rate of acceleration. It is alsomst as if it has lost the remap and gone back to,standard mode. The car will continue to drive but with reduced power. When you turn engine off and restart all the power comes back.

I don't know who did the remap as it was done before I had the car.

Today I have done a major service on the car hoping that it may solve the problem. I have done engine oil change, transfer box oil change, gearbox oil change, diff oils change, changed the radiator and intercooler whilst changing the rubber hoses for silicone. Despite this the problem persists.

I suspect the ecu / remap but I'm guessing ?

Anybody got any ideas that I could try or maybe you have had the same problem.

Thanks in advance for your help

17th Mar 2012 10:41pm

Killer90
Site Sponsor

Member Since: 09 Oct 2011
Location: Hertfordshire
Posts: 6478

2016 Defender 110 Puma 2.2 XS DCPU Fuji White

hmm, you may be hitting top revs and the ecu might not like that, does it start first time or does it seem like it doesnt want to, also check your injector harness under the rocker cover and the plugs to the ecu for oil

17th Mar 2012 11:00pm

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 556

might be worth checking the wastegate rod on the turbo then can seize
Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop

17th Mar 2012 11:06pm

amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Thanks killer 90 I will check the plugs in the morning. I'm aware of the oil problem as I had it last summer and fitted a new injector harness then. I would hope that it would not have come back already? Ps sorry we never got anywhere with jack but glad you got a buyer

Thanks derby will, I will check this also. I have never messed with this before but I'm aware that some people do to achieve better performance. I will lube it up in the morning

17th Mar 2012 11:12pm

GREENI

Member Since: 22 Aug 2010
Location: staffs
Posts: 10381

Injector harness possible, or air flow meter? I've had experience of none genuine air flow meters not liking power upgrades.
Also again as above wastegate rod seizure?

17th Mar 2012 11:12pm

Laurie

Member Since: 22 Feb 2008
Location: Sussex, England
Posts: 2897

2005 Defender 90 Td5 XS CSW Bonatti Grey

Limiter on a TD5 is set at 89mph.

17th Mar 2012 11:14pm

robpenrose

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

Sounds electronic if you can boot it through the gears then it doesn't like full speed.

I have a similar problem. Mine doesn't like full throttle, even for a split second without the engine revving, which sorts itself out after a reset. I suspect possible pedal, but does sound slightly different to yours... Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

17th Mar 2012 11:14pm

amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Thanks greeni,

Can you clean the mass air flow sensor? If so how do you do it..?

17th Mar 2012 11:14pm

amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Thanks robpenrose,

I did consider the accelerator pedal as I had a driver demand error that lit up the engine management light after a little to much of a soaking at Salisbury a few months ago. I suppose it may be connected?

Will look into that

17th Mar 2012 11:18pm

amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Laurie wrote:
Limiter on a TD5 is set at 89mph.

The car will do this speed but it cuts out well before it gets to this speed

17th Mar 2012 11:19pm

JWL

Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

amondeggs wrote:
Laurie wrote:
Limiter on a TD5 is set at 89mph.

The car will do this speed but it cuts out well before it gets to this speed

Mine's gone a bit further than that according to the splat nav

17th Mar 2012 11:24pm

amondeggs

Member Since: 06 Mar 2011
Location: Telford
Posts: 452

Mine's gone a bit further than that according to the splat nav

[/quote]

Before these gremlins started it would do just about 90, although I would very rarely push it to that.

It has the power loss above 70 mph as you accelerating up. After it happens the car will still continue to accelerate but very slowly. Very strange

17th Mar 2012 11:28pm

Killer90
Site Sponsor

Member Since: 09 Oct 2011
Location: Hertfordshire
Posts: 6478

no probs regarding the jack

and mass air flow youll have to buy another

no cleaning it out mate

17th Mar 2012 11:52pm

wslr

Member Since: 18 Jul 2010
Location: Wellington, Somerset
Posts: 581

Your MAF may be maxing out and then putting the ECU into a default setting. You can watch it on Testbook. MAF will jump up past 640kgpa and then it goes off the scale at which point the ECU presumes the MAF has a problem and starts running a basic default. That's the point at which the lack of power starts, and when you back off the power, the ECU sees a good reading again and everything appears normal.

Ask Gary for an uprated MAF sensor.

18th Mar 2012 12:02am

robpenrose

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

Try unplugging the MAF and see if the same problem occurs.. Current:D4 HSE
Gone: BMW Z4MC
Gone: Defender TD5 90 CSW
Previous: Discovery TD5 ES (Gone)

18th Mar 2012 12:05am

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