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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
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 Thumbs Up
Post #132185 17th Mar 2012 10:41pm
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Killer90
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Member Since: 09 Oct 2011
Location: Hertfordshire
Posts: 6478
United Kingdom 2016 Defender 110 Puma 2.2 XS DCPU Fuji White
Confused 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 Thumbs Up
Post #132187 17th Mar 2012 11:00pm
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 560
England 2005 Defender 90 Td5 XS CSW Java Black
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
Post #132190 17th Mar 2012 11:06pm
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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
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 Thumbs Up

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 Thumbs Up
Post #132193 17th Mar 2012 11:12pm
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GREENI



Member Since: 22 Aug 2010
Location: staffs
Posts: 10383
United Kingdom 
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?
Post #132194 17th Mar 2012 11:12pm
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Laurie



Member Since: 22 Feb 2008
Location: Sussex, England
Posts: 2897
England 2005 Defender 90 Td5 XS CSW Bonatti Grey
Limiter on a TD5 is set at 89mph. 
Post #132195 17th Mar 2012 11:14pm
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robpenrose



Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338
United Kingdom 
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)
Post #132196 17th Mar 2012 11:14pm
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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
Thanks greeni,

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

Thumbs Up
Post #132197 17th Mar 2012 11:14pm
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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
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 Thumbs Up
Post #132198 17th Mar 2012 11:18pm
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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
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 Rolling Eyes
Post #132199 17th Mar 2012 11:19pm
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JWL



Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443
England 2002 Defender 110 Td5 SW Coniston Green
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 Rolling Eyes


Mine's gone a bit further than that according to the splat nav Whistle
Post #132201 17th Mar 2012 11:24pm
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amondeggs



Member Since: 06 Mar 2011
Location: Telford
Posts: 452
United Kingdom 1999 Defender 90 Td5 HT Woodcote Green
Mine's gone a bit further than that according to the splat nav Whistle[/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 Rolling Eyes
Post #132202 17th Mar 2012 11:28pm
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Killer90
Site Sponsor


Member Since: 09 Oct 2011
Location: Hertfordshire
Posts: 6478
United Kingdom 2016 Defender 110 Puma 2.2 XS DCPU Fuji White
no probs regarding the jack Thumbs Up and mass air flow youll have to buy another Crying or Very sad no cleaning it out mate Wink
Post #132206 17th Mar 2012 11:52pm
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wslr



Member Since: 18 Jul 2010
Location: Wellington, Somerset
Posts: 581
United Kingdom 
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.
Post #132209 18th Mar 2012 12:02am
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robpenrose



Member Since: 15 Jan 2011
Location: Hampshire or Cornwall
Posts: 338
United Kingdom 
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)
Post #132211 18th Mar 2012 12:05am
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