Hi, a work mate was following me today and said that when I accelerated a lot of black smoke came from the exhaust. I had my 03 td5 Disco remaped nearly 2 years ago and its been fine. Could it be an egr valve or worse a turbo? I am mainly doing short journeys at the moment and the mpg has obviously gone down as well. Any ideas or thoughts greatly appreciated

Mine was doing the same, had everything tested and has shown a faulty Egr valve, so options were a new one or blank off.

The obvious answer is in your statement, "short journeys". Take your shoes off and put the biggest pair of BOOTS on you have and give it some welly for a start to get rid of all the ****e it is clogged up with. Short journeys and re-maps do not like the engine to be used as a 30mph runabout. If you can hitch up a loaded trailer or such, and put it under load to clear the crap out, you would find it will probably run a lot better afterwards.

When I got mine remapped I was told that the Mid box was bad for collecting soot and other crap and make the car look like it's smoking. so as Johnboy say's time to get the Lead soled boots on and it for a blast.

the problem can be solved by putting a mid box replacement pipe in.

Other things to consider... a failing thermostat can mean the operating temperature of the engine is lowered, the ECU injects more fuel to compensate...

Similarly, the coolant and fuel temp sensors degrade with age, and can result in the same thing happening. Replace with quality Bosch parts only.

black smoke can be caused by many other things too..
1. as long as it has the EGR still active clean the MAP sensor as it's certainly full of muck and low readings of manifild pressure and temperature would cause overfuelling => black smoke,
2. replace the depression controll valve(the mushroom shaped thing after the MAF)..IMO it should be considered a partial service item(replaced at every let's say 20.K miles as it's a simple plastic valve exposed to very hot oily gasses so ven if it works it might not work properly => crankase gas overpressure in the admission => mixed up MAF readings...the MAF readings can be altered by clogged EGR aswell also the EGR management is mixed by bad MAF readings(it's a vicious circle) => black smoke
3. bad AAP sensor readings(the one in the airbox) => black smoke

the real answer would be given by live data readings anyway

To add to my last the garage has told me my exhaust manifold is up the Creek which has been contributing to everything so that is being replaced on warranty also.

Thanks for your views, helpful as always. I m normally able to give it a blast up and down the A1 going away on weekends but with winter I haven't been away much just commuting to work etc. I was already thinking of blanking the egr off , have many of you done this and is there a noticeable difference in performance/mpg?