Nigel the Disco

Nigel the Disco

Member
Guys, I need a bit of advice.....my Discovery went for MOT last week, and among other things - bit of easy welding and some bushes - it failed on emissions. I now nothing about diesel emissions really, this is the newest vehicle I've ever owned. It's done just over 210,000 by the way.

The smoke test gave an average of 6.35 against a plate value of 2.18, so a quite large fail. The engine is completely standard part from no EGR. No codes showing on my Nanocom.

I don't drive slowly, but seldom rev over 2,500, and I do about 6 miles each way to work each day. and most of my driving is at lowish speeds. I've put injector cleaner through the system.

Any comments?
 
Give it an italian tune up, ie rag its arse off for 20 odd miles, right before the mot.

Im not slagging you off, but it always annoys me when people say they dont rev it above a certain rpm, why not? it is a diesel make it work for a living they will thank you for it.
This is one of the reasons people are having issues with the new Euro6 stuff as they are trying to get mega mpg by driving carefully but the engine cant get hot enough to stay clean enough.

I dont always rag mine and also do a short commute of 5 miles, but when the oppurtuniy arises and the engine is warm enough it gets a right thrashing!

As my mot man told me if there is no visible plate, they have to test it to the diesel std of 3.00 wink wink:rolleyes:
 
what year is the vehicle? was the MAP sensor cleaned after the EGR was removed? ... and if you know it's old change the depression control valve
 
Nigel the Disco said:
Guys, I need a bit of advice.....my Discovery went for MOT last week, and among other things - bit of easy welding and some bushes - it failed on emissions. I now nothing about diesel emissions really, this is the newest vehicle I've ever owned. It's done just over 210,000 by the way.

The smoke test gave an average of 6.35 against a plate value of 2.18, so a quite large fail. The engine is completely standard part from no EGR. No codes showing on my Nanocom.

I don't drive slowly, but seldom rev over 2,500, and I do about 6 miles each way to work each day. and most of my driving is at lowish speeds. I've put injector cleaner through the system.

Any comments?
Click to expand...
Stick a bottle of cataclean (diesel version) in the tank and give it a good thrashing. I did and it went from over 8 down to 0.14 !
 
I'm wondering how would that "cataclean" help if it's Eu2 without CAT and the MAP is dirty or DCV is fubar? :confused:
 
2001 Eu3, yes I have cleaned the MAP, and the MAF is new, and not cheap. I don't rev because that's how I drive, in the torque curve.

When the welding ans stuff is done I'll give it a good hard drive, see if that does it.....

And, I'll change the MDV
 
Nigel the Disco said:
Guys, I need a bit of advice.....my Discovery went for MOT last week, and among other things - bit of easy welding and some bushes - it failed on emissions. I now nothing about diesel emissions really, this is the newest vehicle I've ever owned. It's done just over 210,000 by the way.

The smoke test gave an average of 6.35 against a plate value of 2.18, so a quite large fail. The engine is completely standard part from no EGR. No codes showing on my Nanocom.

I don't drive slowly, but seldom rev over 2,500, and I do about 6 miles each way to work each day. and most of my driving is at lowish speeds. I've put injector cleaner through the system.

Any comments?
Click to expand...
Its a diesel so just take the air filter out, run it a bit and reMOT it, all will be well.
You will probably find the air filter needs changing when you get it out.
Don't tell everyone else though because they will all be doing it.
 
Interceptorxj said:
I doubt that, there won't be many stupid enough to drive their pride and joy without an air filter.
Click to expand...
I won a rally championship without air filters. Kept setting the piper sponge filter on fire!
Wouldn't recomend it long term though.
For the MOT though you'll find it'll give the best test figures you will get.
You need a new filter is what i'm advocating - doh!
 
What many don't know regarding air filters is they are fitted for if the car is sold into dusty environments

they UK isn't one so you shouldn't need to worry about running it without, think of how many classic race cars and bikes ran without filters under hard conditions and still do
 
LUKBENPHI said:
What many don't know regarding air filters is they are fitted for if the car is sold into dusty environments

they UK isn't one so you shouldn't need to worry about running it without, think of how many classic race cars and bikes ran without filters under hard conditions and still do
Click to expand...

Oh dear!
 
LUKBENPHI said:
What many don't know regarding air filters is they are fitted for if the car is sold into dusty environments

they UK isn't one so you shouldn't need to worry about running it without, think of how many classic race cars and bikes ran without filters under hard conditions and still do
Click to expand...

Interesting but boring fact is very few small boats have air filters fitted at all, though to be fair sand storms are not normally an issue!
Many of the boat engines are very old and thats being polite.
 
Nigel the Disco said:
I don't rev because that's how I drive, in the torque curve.
Click to expand...
Diesel engines are dirty things, and need to be worked hard in order to produce a clean smoke test. If you don't work the engine hard, then it soots up the whole system, from the cylinders, right through to the tail pipe.

However when the MOT tester does the smoke test, he revs the engine to the governor, which blows the accumulated soot out the back, only to be measured by his meter.

So if you drive gently, over time the soot becomes thick, just waiting to fail the MOT.

So before the MOT, give it a few miles of hard running, right up to the red line. This will blow out the accumulated soot, so it's not there when the MOT smoke tester is measuring the particles. ;)
 
Nodge68 said:
Diesel engines are dirty things, and need to be worked hard in order to produce a clean smoke test. If you don't work the engine hard, then it soots up the whole system, from the cylinders, right through to the tail pipe.

However when the MOT tester does the smoke test, he revs the engine to the governor, which blows the accumulated soot out the back, only to be measured by his meter.

So if you drive gently, over time the soot becomes thick, just waiting to fail the MOT.

So before the MOT, give it a few miles of hard running, right up to the red line. This will blow out the accumulated soot, so it's not there when the MOT smoke tester is measuring the particles. ;)
Click to expand...
Agreed, a good thrash is useful and having the engine properly hot is as important too, which most MOT stations do by keeping the car running.
Even so its a lot more to do with the filter replacement.
How many ill maintained A4s have you been behind blowing out loads of black crap everytime they accelerate and everyone of them is undoubtably thrashed.
Helping the engine breathe better leans out the fuel/air mixture and reduces/removes the smoke considerably.
I've gotten rid of it now but I had a transit connect diesel van for a number of years. I serviced it when I first got it and it flew through the MOT.
It flew through every MOT afterwards but I didn't change the air filter and over the first three years the smoke test rose slightly each time.
I then replaced the filter and the smoke test dropped back to the same level as when I first did it.
 
Bantam1 said:
Agreed, a good thrash is useful and having the engine properly hot is as important too, which most MOT stations do by keeping the car running.
Even so its a lot more to do with the filter replacement.
How many ill maintained A4s have you been behind blowing out loads of black crap everytime they accelerate and everyone of them is undoubtably thrashed.
Helping the engine breathe better leans out the fuel/air mixture and reduces/removes the smoke considerably.
I've gotten rid of it now but I had a transit connect diesel van for a number of years. I serviced it when I first got it and it flew through the MOT.
It flew through every MOT afterwards but I didn't change the air filter and over the first three years the smoke test rose slightly each time.
I then replaced the filter and the smoke test dropped back to the same level as when I first did it.
Click to expand...

That wil be because of two things 1 the egr is sticking open and 2 they have some cheap bad boy tune on the car that makes it pull like a train!
 
My D2 just passed MOT with a reading of 0.34
139 k miles, I do not have any smoke at all, even when accelerating hard.
I do use 2so every time I top up and usually don,t go below half tank before filling.
As has been suggested, I did take it for a 10 mile run on the motorway before the MOT
Working it hard occasionally to me works very well
 
I now have an MOT pass - retested on Friday after a few small jobs had been done.

My mechanic did the Italian tune up on the way to the statio, and it came back with a pass.

This particular testing station uses the Hoffman Geogas 5000 exhaust emissions tester, and they don't print out what I'm used to having, so I don't know what figure was acheived. All I know is it's less than 1.5 (the tester applied the limit for post 2008 diesels in eroor, not the 2.18 limit it should be)

Still it's a result and I won't fail on emissions again....
 
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