Emissions fail on MOT

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trevorbayliss

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My 2015 citroen berlingo van has just failed the emissions test on the MOT. It needs to be below 0.7, but was at 4.6. I have just been in for a retest and the reading has come down, but is still over, so they abandoned the test so i can do it again. Now it is 1.34

So i added redox a few days ago and have been driving it harder, as i dont drive it hard at all.

They said to change the oil, so i am doing that this morning. I last did it in septemper with 50k on the clock and i now have 58k on it, so it sort of could use it any way.

My engine a a new one though. Done in 2020 august as i hit a rock it it took out the sump and the engine ran dry for a bit. So under insurance i got a new one.

My worry is that something else is wrong. So just asking on here what i could do. Would i need to clean out the EGR valve ? Our skoda yeti has just had an issue on emmissions, but the EGR valve on there was caked in carbon and it passed after this was cleaned.
 
I don't know about newer French cars, however my diesel HDI (Peugeot 406) is driven carefully and sits at 55-60mph on motorways. Although I feed injector cleaner through it every 1-2k, it does need a bit of blast to clear out carbon deposits. They will build up if you drive like me. I also change the oil before it's done 5k.

Mine actually failed on emissions at the last test, but a squirt of cleaner and a blast on the A50 sorted it. I blanked my EGR off a while ago.

Get on the Berlingo owners forums there are people who will know how to help you here. There is also a FB page. I've been on the 406 owners FB page for years and learnt a lot, including how to change the timing belt which is a pig.
 
Thanks CWH, ive changed the oil this morning and been on the local dual carriageway and run it in 3rd and 4th for a good while.

I also put in a 2 cleaners. The retest is tomorrow. I hope that will do it. If not i suppose i will need to clean the EGR out.

I will check out those others forums !
 
Only my opinion but I find the best additive for this is Forte diesel clean.......you can see the emissions coming down as the test progresses.
A new air filter won't do any harm, but the cat needs to be seriously hot - which isn't as easy as it sounds at this time of year.
John :)
 
Can you get underneath with a blowtorch to get the cat hot? Will that work?
 
i do have a blow tourch and suppose i could heat it up, but is that safe ?

Does any one think this is an EGR valve issue ?

Also can anyone say if i am doing the oil change incorrectly. I dont really use the oil stick to gauge how much to add. It says in the hains manual this engine uses 3.75L oil, so i just measure it out in my measuring jug. Could the engine have to much oil in there ? Just reading tonight about possible causes for this problem. I'm not great with mechanics.
 
trevorbayliss said:
Does any one think this is an EGR valve issue ?
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The EGR, at low engine speeds, opens to allow hot exhaust gas to circulate into the engine air inlet. The result is that oil can be burned into a thick, oily carbon, inside the EGR, the inlet manifold, and the inlet valves - restricting the air flow into the engine. The EGR was a botch by engine designers, to deal with NOX emissions, but as said - they do cause other issues later in the life of the vehicle.

So working EGR or not, fixing it will not help with the emissions, if it is choked up, it will need a thorough clean.
 
Ok, so not the EGR

These are the opacity reads and where it failed. Needs to be below 0.7

4.6
1.98
1.75
1.71
3.37
3.24

Today they retested but pulled it as it failed and they didnt want me to pay for a new test:

1.34
1.35
1.39

So you can see things have improved, but not enough.

I wonder if the oil change will today will help on the retest tomorrow.

Ive been told to add Dipetane to the tank. Halfords sell it and i may add it in the morning. Then go for a long drive as test at 3pm. Luckily i am off tomorrow to sort all this out, but hope it passes
 
trevorbayliss said:
Thanks CWH, ive changed the oil this morning and been on the local dual carriageway and run it in 3rd and 4th for a good while.

I also put in a 2 cleaners. The retest is tomorrow. I hope that will do it. If not i suppose i will need to clean the EGR out.

I will check out those others forums !
Click to expand...
Its okay adding oil according to the capacity as stated in the manual provided ALL of the old oil has been drained out. What about the oil in the block, filter, pump?

Personally, having drained the oil and fitted the new filter I add the new oil till it's between the marks on the dipstick, run the engine, switch off and then add more oil until it is again between the marks.

You should never overfill an oil sump. I would check yours in the morning and drain off any excess somehow.
 
I have a theory on this...
A lightly-loaded diesel engine, never sees much airflow through its inlet tract - turbo, induction hoses, intercooler, inlet manifold. Oil mist enters this tract - usually from the crankcase breather, but in later life, some also gets past the turbo oil seals. It condenses on the colder walls of the inlet tract. During periods of maximum power operation, the high air flow rate through the inlet tract "scours" the oil film off the walls of the pipes (there are many of them in the intercooler, remember) and drags it into the cylinders where it is burned.

However, if the car is never operated at maximum power, this oil just keeps building up. On top of that, you have Mottie's point about the EGR valve, which periodically opens to admit exhaust gas. This can partially burn the oily deposits into sooty gunge, downstream of the EGR valve - which just further clogs everything up.

If that theory is right, (and that's the cause), nothing that you put in your fuel tank will help. You will need to either operate it at maximum power (difficult without losing your licence! Do you have a heavy trailer you can tow up a long hill a few times?) or you'll need to clean out the whole inlet tract. By "operate at maximum power", I mean about 4000 RPM for several minutes with the accelerator pedal on the floor. You can't just do it in neutral, because there won't be as much air flowing through the tubes. The turbo has to be at maximum boost pressure. (Several shorter periods are acceptable). Long up-hill stretches are your best bet. If it's working, it should smoke like a destroyer being pursued by a battleship the first few times, then gradually less.

My sister gave me her old Freelander that she was going to scrap because it failed an MOT on massive smoke. She hates revving it - she thinks it "hurts" them. Here is the result:

IMG_20200913_101021.jpg

And that was the SECOND ice cream tub of gunge that I scraped out of her inlet manifold! (I didn't take a photo of the first one).

Emissions went down from abut 3.5 to 0.98 after that.

Diesels driven hard, rarely seem to suffer from this.

However, if the problem is one (or more) injectors, then the fuel additives will help. Everyone has their favourite potions. Forte and Stanadyne are popular with some taxi drivers I know. I like BG244 (mainly for the smell)!

Regarding oil changes, all the oil rarely comes out of an engine during an oil change, so topping up with the theoretical "new engine" factory figure, is likely to result in a small over-fill - which certainly won't help, so double-check it on the dipstick.
 
If you are doing an oil change you might as well change the filters as well. Both oil and air, they are cheap enough.
 
Old Salt said:
Personally, having drained the oil and fitted the new filter I add the new oil till it's between the marks on the dipstick, run the engine, switch off and then add more oil until it is again between the marks.
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I set my level up, so that when parked on the level, in my garage and cold, it is exactly on the full mark. It has a strange dipstick system, in that you have to pull the dipstick out, count to ten, reinsert it, then pull it back out for a true level reading. Just read it on the first pull, and it will show no oil at all.
 
Avocet said:
I have a theory on this...
Click to expand...

That's a really interesting write-up of your experiences.

Before my Pug 406 I had a 2.0 TDCi Focus. It had good service history but had obviously been driven around by a lady owner on short town/city runs (only found out later). It used to smoke like anything when started up (and smelt like one of those old English Electric trains) and would smoke at random when on a run. New injectors didn't solve it, the DPF had been smashed out prior to my ownership and that hadn't solved it. I blanked off the EGR and that didn't solve it so I sold on (and amazingly it's still out there).

Your theory (if applicable in my experience) would explain the way it ran. My 406 is driven carefully, and sits at 55-60 on the motorways. However once a week I 'floor it' down a slip road onto the M1. It's only even failed on emissions once (the last MOT) and that was solved with a 'keen' drive on the A50 and injector cleaner. They really do need to be thrashed now and then.
 
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