Ok. I've decided to do a thread on my TD4 SE, dedicated to its misfire and what I've done and what I am doing to track down the cause.
Things I've done up to this point are as follows.
First off, about 2 months or so ago, I disabled the EGR valve. After this, I noticed a slight misfire at around 2K Rpm on a trailing throttle.
Reactivating the EGR seemed to cure the problem. However I also decided to start using a fuel additive to help clean the fuel system.
All was well for a few weeks, until 2 weeks ago, I half filled the tank with fuel from my normal budget station but neglected to put in my additive.
Within a few miles, the engine started missing and generally mess about, mostly on light and training throttle.
So I added a dose of my normal additive and half filled the tank with V Power.
This made little difference so I decided to investigate further.
I had already serviced the engine in January, with the exception of a fuel filter as it looked very recent. I filled the engine with quality 5w30 semi, fitting a genuine oil filter and CV filter. At the same time I cleaned out the black goo from the intake system.
Last weekend I changed 3 glow plugs and I fitted a budget £25 MAF off Ebay, which I would normally avoid tbh. At the same time I checked all the injector plugs and did a resistance check on the injector loom. I also blanked the EGR pipes again and took it for a good run. The engine initially ran well, giving more low down torque and losing that delay in power when pressing the throttle.
However once the engine was warmed, it started missing at all throttles except full throttle. So I checked the live values of various sensors to see if I could find a cause.
MAF showed 540 Grams Per Cylinder Per Stroke at idle to around 1500 GPCPS at full throttle @ 3.5K Rpm.
The MAP was 100 KPa at idle to 190 Kpa at 3.5K Rpm.
Low fuel pressure was 360 KPa at idle, dropping to 320 KPa at full throttle.
High pressure fuel rail was 25,000 KPa at idle climbing to around 100,000 KPa @ 3.5K Rpm.
So nothing obviously wrong there.
So last Monday I decided to reactivate the EGR valve for my journey home. Well that was one interesting drive. The engine misfire was very obvious, the instant I drove out of my carpark. Only this time, the missing was accompanied by plumes of black smoke. I drove home, mostly at full throttle, because that was the only time the smoke cleared.
I had other more pressing things going on the rest of the week, I used the wife's Kuga parking the Freelander up until today's fun.
Today I swapped out the Ebay MAF for the original. I also noticed that the oil level appeared high. However that could be me overfilling the engine when I changed it. It didn't smell of diesel but I'll keep an eye on it.
I also decided to go "old school" and use my trusty stethoscope to listen to the injectors running. It was quite interesting to hear them in operation. More interestingly injectors 1 and 2 sounded different to injectors 3 and 4.
1 and 2 clicked with a very hard metallic clack.
3 and 4 made a softer tick, 3 was the quieter than 4.
I listened the injectors at idle and at 2,000 Rpm.
I also checked the injector loom and connectors again.
I also blanked the EGR pipes again. I had also noticed that the engine never goes above 75°C. I assume that the thermostat has stuck open. So I fitted a Renault 5 stat in the top rad hose. That was fun, but it was worth the effort as the engine now gets to 86°C.
That's where I'm at to this point. The car ran fine on the short test drive. I'll see how it goes this week.
If anyone has any ideas on this, then post them up.
I'm suspecting that an injector or two will ultimately fix this, but I want to exhaust all other possibilities first.

sounds like its giving you a right headache mate, ive given up on mine for the time being just driving it.
how far on the temp gauge was it reading before fitting the new thermostat? mine only reaches about a quarter way up unless im towing. you say it ran fine on the test drive, maybe its the stat causing the issues?

hope youve solved it mate. and hopefully your injectors last a while longer for you.

after reading all that ..

i'd be inclined to agree with ..

suspecting that an injector or two

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however .. as ..

The car ran fine on the short test drive.

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maybe the injector cleaning additive will sort it over more time ?

according to rover-ron ..
one sign pointing to an injector fault ..
be that engine is ok when cold but misbehaves once warmed up

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@Gaj1612
The temperature gauge never made it to the mid point, even after long periods at idle. My diagnostic would generally show 60 to 70° C which puts the gauge about 1/3rd up. The thermostat mod has now increased running temperature to 85° C which must help economy.
I'm currently getting 27 Mpg which isn't as good as I would expect.

@hd3
I've done extensive reading on the subject over the last couple of weeks. I'm going to check everything before condemning an injector.
There are 2 things that are a concern at the moment.
1st is the high oil level, which is unlike me to do by accident.
2nd is some blue smoke from the exhaust for a while after starting the engine.

Ok. This morning I drove the Freelander to 13 Miles to work. My daily drive consists of a mix of 6 Miles of 60 Mph B roads, 2 Miles of 70 Mph duel carriage way, 2 Miles of 40 Mph B roads, ending 3 Miles of 30 Mph town roads.
I monitored the engine temperature, MAF, MAP and HPFR pressure.
The engine temperature peeked at 85°C but averaged around 80°C, which is better than it was.
MAF never went above 1100 ( old MAF fitted)
MAP peeked at 175 KPa.
HPFR peeked at 80,000 KPa.
The EGR is blanked at the moment too.
Today the engine ran faultlessly, except for a tiny amount of misfiring at 2K Rpm, only on a trailing throttle. Otherwise it ran really well. All rather odd.

these two ..

1st is the high oil level, which is unlike me to do by accident.
2nd is some blue smoke from the exhaust for a while after starting the engine.

Click to expand...

plus ..

except for a tiny amount of misfiring at 2K Rpm, only on a trailing throttle

Click to expand...

sounds ( or reads ) like an injector needle isn't closing properly

in that .. i take " trailing throttle " to mean ' foot off go-pedal '
and a.f.a.i.k. on modern ecu controlled engines ..
the fuel is supposed to be cut when one takes one's foot off the accelerator
( and if the vehicle speed reduces to almost a standstill the ecu will resume fuel flow for engine idle )
so if a small amount of fuel is still getting into 1 or 2 cylinders on a trailing-throttle ..
could sound like a misfire ..

although it sort of raises the question ..
why at .. ( only ?? ) .. 2000 rpm can a misfire be detected ..

just thinking aloud there .. feel free to pick that theory to pieces
and correct me should i be on the wrong track

( i take it the fuel rail sensor plug contacts are sparkling clean
( and making firm contact .. so vibration ain't effecting the electrical flow
( same goes for injector wiring plugs / sockets
( be worth getting some 'contralube-770' on those btw.

although i suppose your fuel pressure readings would indicate that
the fuel rail sensor be doing its' job ..
and all's well with the pressure regulator on the h.p. fuel pump

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hd3 said:

these two ..

plus ..

sounds ( or reads ) like an injector needle isn't closing properly

in that .. i take " trailing throttle " to mean ' foot off go-pedal '
and a.f.a.i.k. on modern ecu controlled engines ..
the fuel is supposed to be cut when one takes one's foot off the accelerator
( and if the vehicle speed reduces to almost a standstill the ecu will resume fuel flow for engine idle )
so if a small amount of fuel is still getting into 1 or 2 cylinders on a trailing-throttle ..
could sound like a misfire ..

although it sort of raises the question ..
why at .. ( only ?? ) .. 2000 rpm can a misfire be detected ..

just thinking aloud there .. feel free to pick that theory to pieces
and correct me should i be on the wrong track

( i take it the fuel rail sensor plug contacts are sparkling clean
( and making firm contact .. so vibration ain't effecting the electrical flow
( same goes for injector wiring plugs / sockets
( be worth getting some 'contralube-770' on those btw.

although i suppose your fuel pressure readings would indicate that
the fuel rail sensor be doing its' job ..
and all's well with the pressure regulator on the h.p. fuel pump

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Click to expand...

A trailing throttle is where the throttle is still applied a bit, compared to off the throttle completely. So basically it does misfire slightly at 2K Rpm, but only in those situations where I'm going down a slight hill and the engine is helping maintain speed, at very light throttle. If I were to come off the throttle completely, the vehicle will slow down, but it also won't misfire.
The high oil level is something that is a slight concern tbh. Obviously this could well be caused by an injector leaking when switched off. I did smell the oil and rub it between my fingers. I couldn't smell diesel in it and it was the correct consistency and lubricity. So that could be a red herring. I could well have over filled the engine oil in January when I changed it.
I'll keep an eye on it, I might even change it again, just to give me a datum to go on.

A trailing throttle is where the throttle is still applied a bit

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oh .. :-/
i did google the phrase .. saw much about it related to steering ..
'n one definition suggested foot-off accelerator ..
anyway .. above theory trashed 'n back to the drawing board ..

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hd3 said:

oh .. :-/
i did google the phrase .. saw much about it related to steering ..
'n one definition suggested foot-off accelerator ..
anyway .. above theory trashed 'n back to the drawing board ..

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Click to expand...

Trailing throttle is a racing term used to identify the amount of work the engine is doing. On the throttle the vehicle will be speeding up. Off the throttle, the vehicle will slow down. A trailing throttle is something in between, but slightly less than maintaining the same speed.
The way a throttle is used can actually steer a car, some more than others. Most road based cars have pretty neutral handling with regards to throttle input. Racing cars are very sensitive to throttle input, hence the various terms used.

Getting back to the running issue for tonight's trip home. Basically there weren't any. It ran perfectly, the whole trip. There are a couple of decent hill climbs on the home journey, which are coasting on the brakes, going to work.
So I again monitored live data, which goes as follows.
The engine temperature now fluctuates between 78 and 84°C.
The Max MAF reading was 1150 GPCPS.
The Max MAP reading was 215KPa.
The Max HPFR reading was around 120,000KPa. All 3 of the above results were at full throttle @ 3.5K Rpm.
Bizarrely the engine is now running just fine. It has power and torque, although I think it's a bit flat below 2K Rpm, otherwise it's fine.
So I'm now wondering what has caused this problem. Could it have been a batch of duff fuel. Or the fact that I didn't put an additive in with the duff fuel?
It's really really odd.
Maybe the new higher running temperature has something to do with it?
Maybe it's a combination of things.
One thing I am going to do in the coming weeks is a spill test. I know these are not necessarily much use, but hopefully it'll point me in some sort of direction. Which is any bodies guess.

Nodge68 said:

Trailing throttle is a racing term

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Are you saying Freelander is a racing car? Is it likely to knock Mercedes off the top in F1?

GrumpyGel said:

Are you saying Freelander is a racing car? Is it likely to knock Mercedes off the top in F1?

Click to expand...

No but it can be driven in much the same way. Just progress down the road is slower!!

hmmm, interesting, mind boggling stuff. i may just change the stat out of curiosity. you said you fitted one in the top hose, where can i get one of them and any tips on fitting it with feeling inclined to set it alight

Bizarrely the engine is now running just fine. It has power and torque, although I think it's a bit flat below 2K Rpm, otherwise it's fine.

Click to expand...

well that's good news

i did some googling .. ( common rail diesel / misfire at 2000 rpm / trailing throttle )
plenty of "misfire at 2000 rpm" threads on different diesel vehicle forums ..
although with many other added running issues ..
even one LZ thread with a few ppl having that issue .. but no resolve at thread end

anyhow .. got reading thru this .. and searching for "trailing throttle"
http://www.natef.org/natef/media/natefmedia/vw files/2-0-tdi-ssp.pdf
that engine uses 2 valves to transit between idle .. trailing throttle .. and full load
( or similar wording )
one valve be integral with the h.p. fuel pump
the other .. that looks similar to the fuel-regulator valve on the td4 .. sits on the end of the fuel rail
both valves work in unison for a trailing-throttle mode

which had me thinking that your misfire issue might be connected to ..
the fuel rail sensor .. and / or .. the fuel regulator that's attached to the h.p. fuel pump ( td4 )
maybe some grime within the workings of those two ..
which maybe now the fuel system cleaner additive has had time to clean up ..

another google search ..
https://www.google.co.uk/?gws_rd=ssl#q=common+rail+diesel+trailing+throttle
but hadn't read any of it yet .. distracted by tv 'n dinner ..

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although I think it's a bit flat below 2K Rpm

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maf signal i would think ..

if you've not already tried it .. remove that outer sleeve from the air filter ..

( maybe not if regularly ' off-road ' .. or other scene where some
( forceful object might get sucked in ..
( i never see anything larger than an insect or two .. and the odd small leaf
( and .. you'd know more than me with regard to that
( just added for the benefit of any the not-so-mechanical minded readers

anyhow .. to cut a long story short ..
i did .. and the effect / response .. below 1500 rpm .. ( and above ) be just short of 'amazing' ..
well 'amazing' with a ron-box 2a+ / dash switch / and egr bypassed
sort of .. be like adding another number higher to the ron-box selections ..

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meant to ask if this reading ..

High pressure fuel rail was 25,000 KPa at idle climbing to around 100,000 KPa @ 3.5K Rpm.

Click to expand...

was .. or could have been .. monitored in real time .. with the engine being in misfire mode
was wondering if a sudden fluctuation might have occured at 2k rpm - trailing throttle
( taking into account .. looking at readout when driving .. not always easy ..
( and that the reading might fluctuate anyway ..
( have never used said device .. so am clueless ..

thought that the above could have been an issue pointer of sorts

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hd3 said:

well that's good news

i did some googling .. ( common rail diesel / misfire at 2000 rpm / trailing throttle )
plenty of "misfire at 2000 rpm" threads on different diesel vehicle forums ..
although with many other added running issues ..
even one LZ thread with a few ppl having that issue .. but no resolve at thread end

anyhow .. got reading thru this .. and searching for "trailing throttle"
http://www.natef.org/natef/media/natefmedia/vw files/2-0-tdi-ssp.pdf
that engine uses 2 valves to transit between idle .. trailing throttle .. and full load
( or similar wording )
one valve be integral with the h.p. fuel pump
the other .. that looks similar to the fuel-regulator valve on the td4 .. sits on the end of the fuel rail
both valves work in unison for a trailing-throttle mode

which had me thinking that your misfire issue might be connected to ..
the fuel rail sensor .. and / or .. the fuel regulator that's attached to the h.p. fuel pump ( td4 )
maybe some grime within the workings of those two ..
which maybe now the fuel system cleaner additive has had time to clean up ..

another google search ..
https://www.google.co.uk/?gws_rd=ssl#q=common+rail+diesel+trailing+throttle
but hadn't read any of it yet .. distracted by tv 'n dinner ..

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maf signal i would think ..

if you've not already tried it .. remove that outer sleeve from the air filter ..
( maybe not if regularly ' off-road ' .. or other scene where some
( forceful object might get sucked in ..
( i never see anything larger than an insect or two .. and the odd small leaf
anyhow .. to cut a long story short ..
i did .. and the effect / response .. below 1500 rpm .. ( and above ) be just short of 'amazing' ..
well 'amazing' with a ron-box 2a+ / dash switch / and egr bypassed
be like adding another number higher to the ron-box selections ..

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Click to expand...

You mean cut the fluffy covering off the filter? I have read about people removing it but can't see the reason for doing so. The TD4 is a small capacity turbo diesel with a massive air filter for its size. I can't see why a bit of fluffy nylon would make much, if any difference. I will try it however. I might just be surprised.

hd3 said:

meant to ask if this reading ..


was .. or could have been .. monitored in real time .. with the engine being in misfire mode
was wondering if a sudden fluctuation might have occured at 2k rpm - trailing throttle
( taking into account .. looking at readout when driving .. not always easy ..
( and that the reading might fluctuate anyway ..
( have never used said device .. so am clueless ..

thought that the above could have been an issue pointer of sorts

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Click to expand...

The figures are being read off the diagnostic device screen in real time while driving. It's not easy to do so there's likely to be missed info. The displayed figures update every second or so, which also makes for difficult reading.
The HPFR pressure does fluctuate with throttle position. Idling is about 25,000KPa this climbs to about 125,000KPa at full power. That's a scary pressure at over 18,100 Psi!!

You mean cut the fluffy covering off the filter?

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yeah ..
well mine was a bit dirty @ 6k miles when i did that
i'll try and keep this short ..
had been messing with the ron box settings
next day's outing .. engine response below 15k / 16k rpm seemed dull to say the least
thought maybe dirty air-filter .. or fuel filter .. although the latter didn't make sense

so removed the air-filter sleeve .. that had some dirt / black oily stuff / an insect in it ..
paper underneath looked fairly clean .. ran a vacuum cleaner hose over it anyway ..

wasn't too worried that day .. serene driving conditions all day ..
engine seemed ultra smooth and quiet ..
next day needed to overtake an old looking ( read probably low on bhp ) hgv at the start of ..
a moderately steep dual.c. A road ..
had an older jaguar car tailgating me at the same time .. impatient to zoom up said hill
( going by the way it entered the rounabout )
so i gave full go-pedal in 4th gear .. and instead of zipping by the hgv and experiencing a boost at 28k rpm and above
i embarrassingly crept past the hgv seemingly in slug-mode ..
looked at the tach. .. 2800 rpm and slowly climbing .. ( where's that extra ooooomph ? .. ron-box on '10' ffs !!! )
passed the hgv .. pulled over to let jag. past ..
i moved into 5th gear .. thinking torque might rob that old jag of zipping by ..
( it went by at a steady pace .. but not high velocity ..
( guessing an inline 6 n.a. .. but then i don't know old jags engine specs ..

so figured something was really amiss with mine
one lay by / dog toilet stop .. later ..
looked at ron-box and found the problem ..

i had previously turned the power switch 'off' by accident ..

now with ron-box back online ..
my usual setting '10' mode was a bit too go-pedal sensitive ..
and the dash switch settings of 'eco 1 and 2' were finally useful
i wouldn't use those before due to too much hesitation at lower rpm .. hated them ..
was useful in power mode only
Now .. 'eco 2' be just right for regular driving ( mild maf mapping .. slightly lower fuel pressure )
even plenty of poke for low risk fast overtaking
has sort of made power setting '10' a bit redundant for using all day ...
but it's there if desired .. at the flick of a switch ..

best of all from my p.o.v. ..
be that any hesitation pre 1500 rpm is now gone altogether

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edited to add ..
was reading some reviews on 'performance air filters'
standard paper filters were rated at 99.7% filtration efficiency
( or was it 98.7% maybe )
oiled cotton and foam filters at 77% filtration efficiency

one mechanic reported pitted exhaust valves after working on a few cars
that had used k&n filters ..
small micro-debris enters .. gets heated up .. pressurised by combustion
and blasts at the exhaust valves ..

( added for readers contemplating performance filters )

i have a k&n .. but went back to using the standard paper one
( after reading something Nodge had posted )
and even with the k&n ..
i weren't impressed or inspired with the 'eco' dash-switch settings on the ron-box

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end

I am looking at getting a ron box but need to get the injectors working correctly first.
I'll try this air filter mod though.

Just a little update that I think is relevant to solving some of the misfire issues. This morning I was monitoring the same engine data as I have previously. Whilst I was stuck behind a slow moving vehicle, I felt the engine missing slightly. The gearbox was in 4th with the TC locked. I was just on the throttle at the time with the engine turning at 2,000 Rpm. I took a quick glance at the diagnostics screen. I noted that the engine temperature was shown as 62°C. All other readings were as I expected to see.
So now I'm thinking that the engine temperature has a massive influence on the way it runs, particularly at light throttle settings.
Investigation will continue.