I have had my Defender TD5 for just over a year now, it runs pretty much OK but is a bit gutless when cold and I am not sure it performs as intended when hot, it always seems to sound like one cylinder is not performing correctly and rather than a smooth roar I seem to be able to detect each rev of the engine, this is not a mechanical balance issue because when I am going down hill and back off the throttle the engine is very smooth.

Yesterday I decided to look at the turbo boost, I attached a T piece into the waste gate actuator pipe, connected a 0 - 30 Psi glycerine filled gauge on a long tube and put it in the cab.
I took it out and pushed it hard up hill and found the boost pressure hit maximum of about 13 - 14 Psi, before you detected the waste gate open and the pressure fell back slightly.
I adjusted the waste gate linkage, until it hit a maximum of 16 - 18 Psi boost when pushed hard and it felt much better.
on the last run up the hill I heard a muffled boom and a whistle and the engine lost power and started giving out clouds of black smoke,
limped half a mile up to a lay by and found that the silicon boost pipe going into the intercooler had blown off, re fixed the jubilee clip and tightened it up and all was OK again.

When I arrived home I started to think about this and I wonder if anyone might know why :
Without the turbo the engine was dead flat and giving out huge clouds of black smoke, but should the manifold pressure sensor have detected the fall in inlet pressure and adjusted the fuel to a much lower level to take account for this, i.e. the engine would be running like a normal aspirated diesel?
I can understand the performance falling way down this is natural with no boost but why would it kick out all of that black smoke?
I am wondering if the manifold pressure sensor is goosed.
Anyone else had any experience of this situation?

you can remove the map sensor and clean it with carb cleaner, if your egr is still connected it will probably be gunked up

I took off the EGR about 8 months ago and cleand the map sensor at the same time, wondered if that could kick off the problem, I used brake cleaner and did it as carefully as possible, about the same time I changed the mass flow sensor which seemed to make the engine feel a bit more willing.
I will clean the sensor again it won't take long and it's easy to do.

Just taken out the MAP which looked clean, gave it a squirt with brake cleaner and dried it on clean paper then replaced.
Took it out for a run and it seems to have a bit more go when it is cold if I keep the revs up a bit I don't have to change down so much.
I need to run it for a while check how it goes and look at the MPG, to see how it is performing I am determined to have it running as it should.

Id be a bit careful about using Carb or Brake cleaner on sensors, try using IPA, its much less aggressive.

Material compatibility page, for anyone whos bored!

http://www.efunda.com/designstandards/oring/oring_chemical.cfm?SM=none&SC=Xylene#mat

You should find somebody with tester and take some live data readings cos only cleaning sensors is not the way to diagnose things, if any reading is out of range it can cause running/mpg issues but you cant see that without tester

sierrafery said:

You should find somebody with tester and take some live data readings cos only cleaning sensors is not the way to diagnose things, if any reading is out of range it can cause running/mpg issues but you cant see that without tester

Click to expand...

I begin to think you are right live data is the only real way to see what's happpening and if the sensors are giving decent believable output, without that you seem to fall into the cycle of suspecting different faults and just chucking parts at it.