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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
Intermittent Flat Spot
The wife borrowed the Td5 at the weekend for a 500 mile round trip. Not only did it come back with crisps in the footwells Evil or Very Mad, it also returned with an intermittent flat spot between 1000-1500rpm. When sluggish, full boost returns (with a vengeance) from 2000rpm. Based on this I'm suspecting a MAF issue. I've heard that ~160g/s @ 2K is about right. The Nanocom reports ~105 @ 2K when its being sluggish, but sometimes (like on the way to work this morning) the truck feels fine and the Nanocom reports ~160 @ 2K.

The MAF sensor was replaced with a Siemens VDO unit less than a year ago. Is it unknown for these to go "out of spec" and misread? Or is there anything else that could cause these symptoms?

Should all 3 throttle tracks give the same reading on the Nanocom? My tracks 2 & 3 are equal, but track 1 is showing about half the voltage.

Something else which may be related is that her return journey involved torrential rain and she reported a momentary misfire/hiccup whilst on the A31 Hogs Back during the monsoon. I've not experienced this since.

Thanks

John
Post #649774 12th Sep 2017 8:55am
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gazman



Member Since: 17 Aug 2015
Location: Liverpool
Posts: 652

United Kingdom 2003 Defender 90 Td5 HT Alpine White
Regarding the hi cup, mine used to do it in very heavy rain too. I went through a phase of turning the snorkel head around in very heavy rain as it was always worse when in a lorries spray.

I accidently solved mine but I'm not sure what it was, it was either (most likely) the sensor on the transfer box that tells it to go into the different throttle map for low box, I disconnected it and shorted the connection to make the switch constantly closed as id had problems with it.
I also changed the injector harness and made a little guard to divert spray away, but this has since fell off and it still doesn't do it 2014 - current ..... 2003 defender td5 90 (my car)
2009 - current .... 2005 zx10r
Post #649785 12th Sep 2017 9:56am
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gazman



Member Since: 17 Aug 2015
Location: Liverpool
Posts: 652

United Kingdom 2003 Defender 90 Td5 HT Alpine White
Does it run better with the maf disconnected? When mine cocked up it ran fine without it, but a bag of turf with it 2014 - current ..... 2003 defender td5 90 (my car)
2009 - current .... 2005 zx10r
Post #649786 12th Sep 2017 9:58am
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
The value at 2K revs I don't know as it is really depending on the load on the engine on that moment.
At tickover it should between 55 and 65. if it reads about 40 it's not good and if it read 4 it's dead. Twisted Evil
You should get 500 or above at full power and high revs.

You could try to clean it. However be carefull as I managed to kill one so I know that a 4 reading is not a good value. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #649805 12th Sep 2017 11:10am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16812

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
On the TD5 with a three track throttle position pot, one track is reversed, i.e., two vary from 0 to 12V, and one varies from 12 to 0V.

The idea is that the sum of the reverse track and one non-reverse track should be a constant voltage, this is monitored in the ECU for fault detection purposes.
Post #649815 12th Sep 2017 11:48am
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
It is 0 to 4.5V and 4.5V to 0. but further you are right. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #649837 12th Sep 2017 2:13pm
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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
roel wrote:
The value at 2K revs I don't know as it is really depending on the load on the engine on that moment.
At tickover it should between 55 and 65. if it reads about 40 it's not good and if it read 4 it's dead. Twisted Evil
You should get 500 or above at full power and high revs.

You could try to clean it. However be carefull as I managed to kill one so I know that a 4 reading is not a good value.

At ~750rpm tickover it reads ~44g/s, but then so did another perfectly functioning Td5 checked using the same Nanocom. It shows 4g/s with the engine switched off.

roel wrote:
You should get 500 or above at full power and high revs.

I've never seen mine exceed 330 even when performing properly. However, the other Td5 exceeded 500 when pushed.


Last edited by Intercept on 12th Sep 2017 2:46pm. Edited 2 times in total
Post #649840 12th Sep 2017 2:40pm
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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
blackwolf wrote:
The idea is that the sum of the reverse track and one non-reverse track should be a constant voltage, this is monitored in the ECU for fault detection purposes.


Neat Thumbs Up
Post #649842 12th Sep 2017 2:42pm
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jonny2tanx



Member Since: 06 Jul 2014
Location: Harpenden, Herts
Posts: 156

United Kingdom 2005 Defender 110 Td5 XS CSW Alveston Red
I had a similar issue a few weeks ago whilst driving through Poland towards Belarus. We were on the motorway and were in a torrential downpour which made me slow right down to less than 20mph until I could get off the motorway. Before I could the car started to play up, losing power, and the Nanocom which I had in instrument mode showed a massive drop in airflow, down to 0 then back up. When I could check It the brand new air filter was filthy and clearly had got drenched. It dried out and was usable until the brother in law flew out a week later with a new air filter for me. Have a look there. I also changed the MAF to be on the safe side but tbh I think the original was ok. At least I now have a spare one. Rolling Eyes
Post #649941 12th Sep 2017 7:37pm
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lightning



Member Since: 23 Apr 2009
Location: High Peak, Derbyshire
Posts: 2159

United Kingdom 
My 2005 TD5 110 reverts to the low range throttle map if you floor the throttle. It's done it since l bought it in 2014, 36,000 miles ago.

Our 2006 90 TD5 did it from new for eight years and 44,000 miles. No solution was ever found.

On my 110 l have to take care not to press the throttle pedal right down, or l will spend the rest of the journey in the low range map.
lt still drives OK but you have to press the pedal further before the turbo comes in, and then it's more progressive in the power delivery.
Turning the ignition off then back on will reset it. Obviously not possible while driving.

£20 via paypal to anybody who suggests a solution which works (you'll have to trust my honesty with that)
Post #649946 12th Sep 2017 7:43pm
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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
jonny2tanx wrote:
I had a similar issue a few weeks ago whilst driving through Poland towards Belarus. We were on the motorway and were in a torrential downpour which made me slow right down to less than 20mph until I could get off the motorway. Before I could the car started to play up, losing power, and the Nanocom which I had in instrument mode showed a massive drop in airflow, down to 0 then back up. When I could check It the brand new air filter was filthy and clearly had got drenched. It dried out and was usable until the brother in law flew out a week later with a new air filter for me. Have a look there. I also changed the MAF to be on the safe side but tbh I think the original was ok. At least I now have a spare one. Rolling Eyes


Interesting - thanks. Earlier today I had a look at the air filter, and it was completely shot despite having done just 6k miles of normal road use. It appears to have been soaked, then collapsed, then punctured by the airflow. The MAF grille also had evidence of liquid splashes. Unfortunately a new filter hasn't improved things so maybe the MAF sensor hasn't enjoyed its shower. I've given it a blast of carb cleaner and compressed air to no avail - it seems to have gone non-linear Crying or Very sad
Post #649961 12th Sep 2017 8:24pm
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gazman



Member Since: 17 Aug 2015
Location: Liverpool
Posts: 652

United Kingdom 2003 Defender 90 Td5 HT Alpine White
lightning wrote:
My 2005 TD5 110 reverts to the low range throttle map if you floor the throttle. It's done it since l bought it in 2014, 36,000 miles ago.

Our 2006 90 TD5 did it from new for eight years and 44,000 miles. No solution was ever found.

On my 110 l have to take care not to press the throttle pedal right down, or l will spend the rest of the journey in the low range map.
lt still drives OK but you have to press the pedal further before the turbo comes in, and then it's more progressive in the power delivery.
Turning the ignition off then back on will reset it. Obviously not possible while driving.

£20 via paypal to anybody who suggests a solution which works (you'll have to trust my honesty with that)


disconnecting the switch on the transfer box under the landy drivers seat area. Mine was shorting out and giving me grief like you describe. I ran it open circuit for a while and I'm sure they are now bridged 2014 - current ..... 2003 defender td5 90 (my car)
2009 - current .... 2005 zx10r
Post #649985 12th Sep 2017 9:53pm
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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
Problem not yet solved but I'm suspecting a drenched air filter was probably the root cause. I'm wondering if the dump valve isn't working properly - can it be removed for checking?


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Post #650026 13th Sep 2017 9:11am
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554

dump valve first one in line yes can be removed two j clip also check drain valve in bottom of air box
Post #650046 13th Sep 2017 10:28am
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gazman



Member Since: 17 Aug 2015
Location: Liverpool
Posts: 652

United Kingdom 2003 Defender 90 Td5 HT Alpine White
Shocked Shocked Where is your air intake? I dont have any drains on mine as they are all sealed for wading bit mine has never looked like that! 2014 - current ..... 2003 defender td5 90 (my car)
2009 - current .... 2005 zx10r
Post #650062 13th Sep 2017 12:01pm
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