Diesel car failed nct on emissions

firestarter51

I have a 2010 308 emissions were 4.6 and should be 1.5 max, tester said it's due to city driving, I live in the country and use motorways a lot but any way
Took it to a mechanic near me, he plugged it in to his diagnostic, nothing showed up, so he said there is nothing wrong with the car and to open it up and drive at 4k revs to blow out all the soot, and I should fill up at topaz as I must have got bad diesel somewhere
I'm happy to do this, but my worry is, is he spoofing as I don't want to do a re test and it fail again, any help on this would be great thanks

firestarter51

Sorry I should also have said, the main dealer said they would have driven the car in third gear on the motorway and checked if it was clear.
It's serviced regularly too

JC01

Clean out the EGR valve and bring it for a hard long drive, costs ya nothing and solves emissions problems on loads of cars, that'd be my first port of call and see what it's like after

Dark sun

firestarter51 wrote: »

Sorry I should also have said, the main dealer said they would have driven the car in third gear on the motorway and checked if it was clear.
It's serviced regularly too

But some diptane when you car is almost empty( when the refuel light comes on) put the whole bottle in your tank give it a good drive, also on the motorway get the revs up to the red line, only do this when the engine is fully warmed up, and before you test give it a good spin.

Kimbot

Dark sun wrote: »

But some diptane when you car is almost empty( when the refuel light comes on) put the whole bottle in your tank give it a good drive, also on the motorway get the revs up to the red line, only do this when the engine is fully warmed up, and before you test give it a good spin.

A whole bottle? :O

I have a bottle beside me, its 1 Litre and its divided up into sections (0, 10, 20, 30 etc upto 200) each section treats 10 Litres of fuel so max youll be using is about 5/6 sections to treat a full tank. I failed on my NCT in a 1.9TDI aswell, used one batch of it and passed the retest no problems.

firestarter51

Is it worth going to the main dealer to get the emissions checked before hand or will theses tips be ok to go straight for the re test

Old diesel

firestarter51 wrote: »

Is it worth going to the main dealer to get the emissions checked before hand or will theses tips be ok to go straight for the re test

You could try putting it in for the retest again with the tips already suggested - a potential issue is that there MIGHT be some underlying issue with the car not picked up.

But you can revisit that IF the car fails the retest again

Old diesel

Incidentially - with the OPs situation - does he or she actually need the services of someone who is good with diagnostics - rather then someone who just plugs in a machine and reads the fault codes????.

Chimaera

Are you normally a gentle driver? If so, you've probably built up a lot of soot in the exhaust manifold and turbo over the years. If you're lucky, a good hard drive will dislodge it and send it out the exhaust pipe.

I'd get a proper fuel additive, something like Millers Diesel Power EcoMax or LiquiMoly Diesel Purge and run it through at relatively high concentration. With the Millers, put in two 50 ml shots in a full tank. With the Diesel Purge (if you can get it) add the full litre bottle to an empty tank and fill up with another 5 l of fuel. Get the car warmed up by driving normally for 15-20 km then redline it in third on the motorway a few times (obviously being mindful of speed limits) to drive the crap out of the exhaust. Keep an eye on the exhaust to see if it's clear or smoky. If it's just soot buildup, this will clear it quickly enough. You could consider asking the dealer to do a manual DPF regen after this too.

If this doesn't solve the issue, then you've got a bigger problem with the engine. Consistent smoke in a diesel car means it's overfuelling, either from not getting enough air, or from getting too much fuel. A diagnostic scan may not necessarily show up issues here. I'd try the fuel additive and Italian tuneup first and see if that solves the problem before getting too excited about other possibilities.

jimgoose

Chimaera wrote: »

...I'd get a proper fuel additive, something like Millers Diesel Power EcoMax or LiquiMoly Diesel Purge...

BG244K is also mighty stuff.

dr.fuzzenstein

Been hearing a lot of good stuff about Comma:
http://reviews.halfords.com/4028/264671/reviews.htm
I just stuck a bottle in my tank, was having a bit of smoke and uneven running, it definitely runs better.

firestarter51

I drive it fairly handy, it's never under pressure, I just got the car from the mechanic he advised me to give it a good hard run once a week, he said it happens quite a lot, fella I spoke to last night was his father, I don't think the lift goes fully to the top floor
Thanks for the advice, I will do the things suggested and see if it passes on Wednesday
Fingers crossed

Kopparberg Strawberry and Lime

jonny24ie wrote: »

A whole bottle? :O

I have a bottle beside me, its 1 Litre and its divided up into sections (0, 10, 20, 30 etc upto 200) each section treats 10 Litres of fuel so max youll be using is about 5/6 sections to treat a full tank. I failed on my NCT in a 1.9TDI aswell, used one batch of it and passed the retest no problems.

very safe to do this !

im doing something similar myself, i haven't had the nct yet but i notice smoke when boosting so i put a full tin of novafuel powerkleen into an empty tank and drove the nuts of it down the motorway, will be out driving today to hoping to see results !

Kimbot

Just make sure your really warm up the engine before you go in as a cold engine will lead to a higher result.

firestarter51

Well, it passed.
I got a new fuel filter and filled that up with dipotine, it took about a third of the bottle, drove at 4k rpm for a while, engine was good and hot going in, they tested more than the emissions though which I was surprised about, did all the stuff that's done at the first bay.
Emissions were 1.3, max allowed for my car is 1.5
Thanks for the help lads I know what to do next time

Chimaera

1.3 is still very high, and needs to be checked out further. My car was only at 0.36 on its last test at 14 years old and 267000 km.

Getting it down low enough to pass the NCT is not the same as fixing the problem. Find a good mechanic and get the problem sorted before it leads to bigger and more expensive problems.

Kopparberg Strawberry and Lime

firestarter51 wrote: »

Well, it passed.
I got a new fuel filter and filled that up with dipotine, it took about a third of the bottle, drove at 4k rpm for a while, engine was good and hot going in, they tested more than the emissions though which I was surprised about, did all the stuff that's done at the first bay.
Emissions were 1.3, max allowed for my car is 1.5
Thanks for the help lads I know what to do next time

Congrats that it passed !

is it the 1.6hdi model by any chance ?

firestarter51

Kopparberg Strawberry and Lime wrote: »

Congrats that it passed !

is it the 1.6hdi model by any chance ?

It is yes

Kopparberg Strawberry and Lime

firestarter51 wrote: »

It is yes

I ask because its the same engine in my own car.

i just did the nct yesterday !

passed emissions with 0.13 /m the limit for my car is 3.00 /m

so maybe some more hard driving on your own car with more diptane will bring that down more.

firestarter51

Kopparberg Strawberry and Lime wrote: »

I ask because its the same engine in my own car.

i just did the nct yesterday !

passed emissions with 0.13 /m the limit for my car is 3.00 /m

so maybe some more hard driving on your own car with more diptane will bring that down more.

That's what my mate told me to do, he is a mechanic at a main dealer, he said soft driving is no good for the car, and there will still be soot in the car, I will be using topaz now and open it up every week.
Is yours an older model as it's 3.00 and mine is 1.5 ?
How often do you drive your hard out of curiosity ?

Kopparberg Strawberry and Lime

firestarter51 wrote: »

That's what my mate told me to do, he is a mechanic at a main dealer, he said soft driving is no good for the car, and there will still be soot in the car, I will be using topaz now and open it up every week.
Is yours an older model as it's 3.00 and mine is 1.5 ?
How often do you drive your hard out of curiosity ?

mine is 2005 focus but i pulled the engine out of a 2008 peugeot 308

i drive hard rarely but when i drive hard its a good one ! !

firestarter51

Kopparberg Strawberry and Lime wrote: »

mine is 2005 focus but i pulled the engine out of a 2008 peugeot 308

i drive hard rarely but when i drive hard its a good one ! !

This is my first diesel so it's new to me, my first nct as well I used to trade in every couple of years, but the mpg is so good on this I'm keeping it, I must ask the mechanic how often to drive it hard