MOT advisories - Diesel Emissions Test

Coveredinbees!!!!

On my last MOT one of the advisories was - emissions tested to plate limit of 0.60.averaged 0.53.

I fixed everything else but I'm not really sure if the above is a problem or not and if it is how do I fix it?

I did run a bottle of something through it after the last MOT on advice from the local Milehams, it could have been injector cleaner but I'm not 100% sure, it was added to the fuel.

The next MOT is due soon so would rather do something now if it need doing than have it fail. It's a Ceed if that helps.

AdrianC

It's the measure of the opacity of the smoke from the exhaust. 0.53 against a target of 0.6 is not really a problem - 0.6 is pretty damn clean. Let's put it this way - pre-2008 turbodiesels have a default limit of 3.5...
(No, don't ask what - the units are slightly more opaque than a knackered old diesel's exhaust)

All an advisory is is the tester saying *"You ought to be aware"* of something that's passed the test. He's simply telling you what the emission figure is. It passed. Your particular car is marked as having a limit of 0.6. Assuming it's 2014 or later, the default if it wasn't marked would be 0.7.

Goop to add to the tank is great if you're into homeopathy, otherwise it's more of a nice little earner for the people flogging it you.

Coveredinbees!!!!

Thanks. So I have been had.

AdrianC

Coveredinbees!!!! said:

Thanks. So I have been had.

For the goop? <shrug> Some people swear blind it works. Some people swear blind homeopathy works... 

Take a typical diesel injector cleaner...
https://www.wynns.uk.com/product/injector-cleaner-for-diesel-engines
Add 325ml to "minimum" 20l. Well, most people are going to tip it into a tankful - so say 65l. 200:1.
And you only need use it every third tank. 600:1.
Then look at the MSDS safety data sheet for it.
https://www.wynns.uk.com/wp-content/uploads/sites/17/2015/09/w51668-injector-cleaner-for-diesel-engines-e04.00-en-1.pdf
It's 90%+ "hydrocarbons" (that's basically diesel, then).
5-10% is 2-ethylhexyl nitrate, which is a "cetane improver" - basically, the resistance to ignition. Does the cetane rating of diesel need improving? Why? The engine's designed to run on standard fuel...
<1% is "aromatics" (makes it smell nice).

So about 1/6,000-1/12,000 of the fuel you're burning with the goop in is a cetane improver. Not that the cetane necessarily needs improving.

But putting it in post-test is a bit unnecessary anyway, because it's another year until the smoke opacity is actually going to be measured. Best thing you can do to keep smoke down on any diesel is drive it properly. Don't !!!!!!-foot it, and definitely don't just use it for short trips. And definitely give it plenty of welly and get it nice and hot just before the test. That'll all help the DPF and EGR generally, not just give you a fuzzier comparison between two numbers once a year.

32Battalion

Just make sure the car is fully warmed up when you arrive at the test station, don't arrive with a cold engine.

Scrapit

take it for a decent run the day of the test. Give it some boot and blow the cobwebs away(and any soot).