Diesel emissions - MOT

[Jack]

Well, J501 FVF has let me down. It's the only car I've ever had where MOT time does not generally give me any undue nervous ticks, but on this occasion... :suspect:

It failed on a tyre (all four need renewing really which I already knew), and emissions. I've changed the air filter (which was very dirty) and stuck a whole bottle of Redex diesel injector cleaner into 1/4 tank of fuel (the bottle should treat 100 litres!) to clear any problems there.

I then thought it had made a difference but noticed a fair bit of smoke today on hard acceleration. The re-MOT is booked for tomorrow morning - does anyone have any other ideas for reducing smoky emissions?

[Dean]

All I do before I take my diesel for it's MOT is take it a good run, get the engine nice and warm and give it plenty of thrash through the gears. I've never used additives and it's always passed. The engine has 150K on it and a mechanic mate of mine says it's just run-in.

Dean.

[E_T_V]

It is a turbo diesel or a NASP diesel?

Things to do are:
1 Change air filter
2 Clean injectors using dans quick and dirty method!
3 Take it for an italian tune up
4 Reduce the smoke setting on the injection pump.

1 and 3 are very easy to do. Before the test take the car for a run of 10-20 miles. Then now that the engine is good pick a quiet road (not that it'll be quiet for long!). Accelerate from rest in first gear till it his the speed governer (you'll feel the car stop accelerating). Then hold it hear for a second or two. then change gear and repeat in second gear again holding it on the engine governor for a few seconds. So long as your cam belt is good no harm will come from doing this, indeed this is how they do the MOT test anyway. You'll probably be horrified at all the smoke that comes out of the exhaust. Then repeat as necessary till it clears up a bit. If it doesn't then we'll have to look at adjusting the injection pump or cleaning the injectors.
(Both of which are fairly easy to do).

After the italian tune up immediately present the car for its emissions check at the MOT station. Avoid idling the car for any period if at all possible as this is how the smoke builds up.

If you need advice on any of the other things to try then let me know. I'm going to try and write up a guide to tuning the diesel when I get time anyway.

[E_T_V]

As a rough guide as to what the methods listed can do, my 200,000 mile old NASP diesel got through the test with a smoke level of under 1. (limit for NASP diesels is 2.5 - limit for TD's is 3.0 I think).

[Jack]

Mine is normally aspirated. I'll try the acceleration method as the belt is good. Do the speed governors ever fail? The MOT man revved the nuts of it and I just hate to hear the car revving that high, so I'll be going on faith that the governor kicks in!

[E_T_V]

I've not known a governer fail. They should be set at 4,500rpm. You'll just notice that the car/ revs just stop increasing. If you want to be cautious you can do this without the car in gear as it puts less loading on all the components. Perkins conducted one test apparently where they took a turbo prima and ran it on its rev limiter for over 24 hours! :horror: It survived just fine but glowed a nice shade of red :D

[E_T_V]

As for you hating to hear the engine revving that high then I'm betting that is almost certainly why it failed its emissions test. By being kind to the engine it tends to accumulate lots of soot in the engine and the exhaust. Come MOT time they test the emissions on the rev limiter so all the soot gets blown out of the engine and exhaust and it shows up as a fail on the test. Before the test and preferably once or twice a month I let my camper engine rev until it hits the governer. This blows all the cobwebs out and keeps the emissions down and the injectors unclogged.

Quite frequently garages will take a car in for work that has failed its emissions test only to give it a hard thrash round the block a couple of times before re-testing it and more often than not it'll pass the second time around.

[B18 GPC]

Not on the diesle ones?

We use no speed mesurment device on the Disle mOTS.

We Use a probe go get the Engine to a minumum of 60 degrees C , / 80 degress we have found has a higher pass rate.

Then we click on the computer 4 a ten second sount down

On one you "accellerate hard" until the computer says return engine to idle speed. If it fails this repeats for a while. We also run the cars up the road.. to clear it out before the mot.. the environment can have the fumes - no thanks in our work shop :)

[E_T_V]

Not on the diesle ones?

We use no speed mesurment device on the Disle mOTS.

No but the maximum engine rpm on the diesel maestro is factory set at 4,500rpm



We Use a probe go get the Engine to a minumum of 60 degrees C , / 80 degress we have found has a higher pass rate.
Frequently a maestro diesel will take AGES to get up to 60°C and it won't get there if the car is just left to idle so take it for a good run before you get to the station.


Then we click on the computer 4 a ten second sount down

On one you "accellerate hard" until the computer says return engine to idle speed. If it fails this repeats for a while. We also run the cars up the road.. to clear it out before the mot.. the environment can have the fumes - no thanks in our work shop :)

Yes that is what I mean you accelerate hard by flooring the throttle which means the engine will hit the rev limiter. An italian tune up usually works wonders on most diesel emissions failures.

[tony]

[QUOTE=E_T_V]
3 Take it for an italian tune up


that has worked for me in the past 50mph road, 2nd gear and foot flat to the floor for a good 5 mins ,radio up full :sad: :laugh:

[rpcee]

[QUOTE=E_T_V]
3 Take it for an italian tune up


that has worked for me in the past 50mph road, 2nd gear and foot flat to the floor for a good 5 mins ,radio up full :sad: :laugh:

So the type of tune affects emissions? I love hearing these pro tips you'd never otherwise get to know about. Only thing is I don't know any Italian pop would Verdi do? Is there a scientific explanation?

[Ricky]

No, I'm sorry - you'll have to crack out the Eiffel 65, it's about the only Italian thing I can think of at the moment (and that's dubious!), but at least it's almost relevant - "Blue (smoke) Da Ba Dee" anyone?

On another tangent, didn't the aliens in the video look like William Hague??

[tony]

Only thing is I don't know any Italian pop would Verdi do? Is there a scientific explanation?

there was joe sommat with (whats amatter you )
:fim:

[Jack]

Erm...back on topic, the car passed on Saturday. It's a station where you leave it and they fit it in some time without an appointment. I was asked to leave it all day (Saturday's are busy) so it had quite possibly cooled off by the time it was tested. Maybe that's why they let it pass because the sheet said emissions were 2.62 and I read that for a N/A car the limit is 2.50. Perhaps he just took pity on the poor thing and let it thru.? Frankly I don't care as I've got 12 months ticket anyway.

[E_T_V]

If you look further down the sheet you may find that they repeated the test.

From memory they floor it once and make a measurement, if it is low then they just pass it. If it is high then they then take 3 more readings where they work out the average I think. I'll have to dig out the MOT for my van as I remember first time is passed with only one reading being taken and the second time it needed to have 4 readings done.

At least it isn't as bad as my rover which had 3 emissions tests done in sucession and only passed in the last 2 seconds of the extended (2minute?) test! The MOT tester was telling me how it would never pass (CO emissions of 0.6%) which was stable for ages then in the last few seconds of the extended test they dropped to almost zero and the engine note changed.

He was as mistified as I was but he said that it passed so no to bother doing anything to it!