Hi all. My 2010,  90,000 miles diesel roomster failed the mot due to high emissions. 

The garage added some engine cleaner and gave it a good run which brought it down to pass the mot, just. 

They stated they expect it to be an issue next time. 

 

They have always been good in the past so I think they are genuine. 

 

What sort of things could I do to reduce a problem as the rest of the car is in great condition. 

 

Cataclean comes in a bottle and can be purchased from Halfords and ECP. They do a diesel and petrol version which is simply poured into the fuel tank and it helps with removing resin and carbon deposits from the fuel injectors, intake valves, DPF, catalytic converter and exhaust, not only increasing MPG and performance, but also cutting emissions by up to 60%. Worth a go surely.

Edited 14 May, 20197 yr by shyVRS245
SPELLING MISTAKE

Sounds like the DPF is not working as well as it should be. I would be looking in that area rather than hoping for a miracle cure in a bottle.

 

Check around for air leaks, boost leaks= rich running=black smoke which the DPF has to try and contend with.

 

Can you post up the MOT results just for information, what the limit was they were testing it against and what the reading was.

Edited 14 May, 20197 yr by SuperbTWM

Look for fuel additives (bottles that you add after fuelling) or just use best quality premium superdiesel

 

I suspect what they did has shifted some of the gunk that has accumulated, but will take a few more tank fulls to clean it further

 

Whilst stationary look at exhaust (don’t stand right behind it) and get someone else to press accelerator, take it upto about 4000rpm, hold it for 15 seconds, let revs die down, then repeat 2 or 3 times.  See if any sooty smoke comes out.  

 

Next year clear out the soot with good fuel & additives before going to MOT test

 

 

 

 

@SurreyJohn

?

What is the 'best quality premium superdiesel'?  

Is it 

Shell V-Power, or BP, Esso, or some others 'Premium Diesel' ?

 

Buying fuel can be expensive enough without having to further boost Royal Dutch Shells profits to run a regular family size / performance diesel and get it through a UK MOT IMO.

 

If an extra £10 or so spent before a MOT and a bit of an Italian Tune up does the job to get a pass then that works for many.

The day before the mot take your Roomster out and thrash it to within an inch of its life for 20 or so miles. Hard acceleration getting the revs well into the top third of the rev range... drive it like you stole it!

In fact do the above at least once a month. 

A new air filter just before the mot wouldn't go amiss.

 

33 minutes ago, eccleshill said:

The day before the mot take your Roomster out and thrash it to within an inch of its life for 20 or so miles. Hard acceleration getting the revs well into the top third of the rev range... drive it like you stole it!

In fact do the above at least once a month. 

A new air filter just before the mot wouldn't go amiss.

 

 

Great advice.  No need for any snake oil or special fuel.

^^^Great advice.  My Roomster was a 1.9tdi hence no DPF.  But a good thrashing before the MoT ensured emissions were well within limits.

 

Opinions vary on fuel additives.  Some people swear by them, others consider them snake oil.  I'm on the fence - but in OP's position and for the sake of £10, I'd be prepared to give them a go before the next MoT.

 

From a chemical viewpoint, fuel cleaning additives have to fit in with a tight set of requirements - Dissolve the carbonised gunk - Burn cleanly in cylinder - Not contaminate Cat/DPF  - Not cause damage to any fuel system components etc.

Reading the 'Safety Data Sheet' for diesel additives generally show them as simply being a solvent mix, mostly Acetone/Xylene as these are a highly flammable & cheap way of dissolving the gunk we want gone. (Also removes paint if left in contact)

Pure Acetone (99%+) can be bought online for a fraction of the cost of ‘special additives’ and is used in the same way at about 1% max ratio to tank contents (500ml Acetone in 50 litre of diesel), using too much will risk thinning the diesel too far and causing long term wear.

Using any additive type instead of premium fuel is simply a cost calculation, does the extra cost for regular fills with premium diesel cost less than half a litre of this every few months. Either way an Italian tune up pre-MOT is the only way to clear the pipes.

It’s worth remembering that engines are only built to meet current (or soon to be mandatory) standards. Diesel fuel content & quality standards have shifted a lot in the last 20 years, our older engines were designed to use fuel which strictly speaking doesn't exist anymore.

29 minutes ago, GreenOcty1 said:

 

From a chemical viewpoint, fuel cleaning additives have to fit in with a tight set of requirements - Dissolve the carbonised gunk - Burn cleanly in cylinder - Not contaminate Cat/DPF  - Not cause damage to any fuel system components etc.

Reading the 'Safety Data Sheet' for diesel additives generally show them as simply being a solvent mix, mostly Acetone/Xylene as these are a highly flammable & cheap way of dissolving the gunk we want gone. (Also removes paint if left in contact)

Pure Acetone (99%+) can be bought online for a fraction of the cost of ‘special additives’ and is used in the same way at about 1% max ratio to tank contents (500ml Acetone in 50 litre of diesel), using too much will risk thinning the diesel too far and causing long term wear.

Using any additive type instead of premium fuel is simply a cost calculation, does the extra cost for regular fills with premium diesel cost less than half a litre of this every few months. Either way an Italian tune up pre-MOT is the only way to clear the pipes.

It’s worth remembering that engines are only built to meet current (or soon to be mandatory) standards. Diesel fuel content & quality standards have shifted a lot in the last 20 years, our older engines were designed to use fuel which strictly speaking doesn't exist anymore.

That's why some owners of older diesels use old chip fat oil to power their vehicles (smells nicer to).