my superb (1.9tdi 130) is due for mot next week - last year it failed on exhaust emissions being too high but tester put in bottle of ?cleaner and took it for a run at high revs whereupon it passed - charged me £45 for whatever they put in - anyone recommend anything that i can put in now which will clean up the engine/injectors/emissions before i take it for mot and save me a bit of the £45 - halfords/factors seem to have numerous ''diesel engine cleaners'' but i've no idea which to go for

thanks

Did you see the print out for the emissions ? Sounds like a bit of a con, £45 for injector cleaner ?

Total con and contrary to VAG's instructions which contra indicate fuel additives.

Get the engine fully hot (it takes about 8 miles of active driving to get the oil hot) then give it an "Italian tune up". This is what cleared out the soot the last time - not the snake oil.

rotodiesel.

Also if you are concerned put a clean air filter in on the day or day before the MOT as this will produce a cleaner exhaust. Old cars I had would pass just fine on a clean filter.

Actually got the MOT place to do clean filter then put the old one in and the car easily passed the first one and just scraped the second with the dirty filter in.

Other stuff is snake oil IMHO. I did use millers diesel clean, a double dose when it was about £5 a bottle, and would put that in the tank before the MOT then fill up with `clean` fuel for the test.

You were well ripped off m8, a good thrash before test to clear the soot out should suffice

Phil

You were well ripped off m8, a good thrash before test to clear the soot out should suffice

Is that commonly needed? For the first time in years, I got my MOT done at a garage about a mile from my house so the car was stone cold when it was tested. Sailed through though

Chris

Soot isn't tested on MOT (or wasn't when I had a diesel) Its still co2 output isn't it ?

Soot isn't tested on MOT (or wasn't when I had a diesel) Its still co2 output isn't it ?

Nah it's the other way round, CO2 on a petrol and particulates on a diesel

Chris

Nah it's the other way round, CO2 on a petrol and particulates on a diesel

Chris

Correct diesel is just particulate content, the probe up the exhaust takes a sample of the exhaust smoke and shines a light through the sample which then measures the amount of light 'lost' from one end to the other. A bit poor really :P

Correct diesel is just particulate content, the probe up the exhaust takes a sample of the exhaust smoke and shines a light through the sample which then measures the amount of light 'lost' from one end to the other. A bit poor really :P

You learn something new everyday................

You learn something new everyday................

You certainly do. That told me

The metered smoke test has been conducted in EU countries for many years. It is the only emissions test

applicable to Diesel engines. During this test, a calibrated smoke meter is used to assess the density of the

smoke from compression ignition (diesel) engined vehicles. The engine will be accelerated up to governed

speed and the smoke density measured.

The limits for Diesel engine exhaust smoke, introduced in September 1995 are: Vehicles first used before 1st

August 1979: Exempt from metered smoke testing, but must not emit "dense blue or clearly visible black

smoke for a period of more than 5 seconds at idle" or "dense blue or clearly visible black smoke during

acceleration which would obscure the view of other road users". All vehicles first used since August 1979 will

be expected to perform and pass the smoke density test. Engines that emit very little smoke and achieve a

meter reading of 1.5m-1 or less will pass the test after the first acceleration. However, if the test is not passed

on the first acceleration a further two accelerations will be carried out. The average of the three acceleration

readings will be calculated and if the reading is at or below 2.5m-1 for non-turbocharged engines or 3.0m-1

for turbocharged engines, the vehicle will pass this element of the test (Environment Agency, Not Available).

However, if the average is higher, a further acceleration will be carried out, and the average of the last three

readings will be calculated. This will continue up to a maximum of six accelerations. If the average of the

fourth, fifth and sixth accelerations are higher than the appropriate level, the vehicle will not pass the test. In

addition, vehicles may be refused a certificate if the exhaust emits excessive smoke or vapor, to an extent

likely to obscure vision (Environment Agency, Not Available).

A metered smoke test will not be carried out if:

· The exhaust tail pipe is damaged or an accessory is fitted which prevents insertion of the smoke

meter probe.

· The exhaust system is extensively fractured or holed.

· There are obvious signs of an engine defect such as an unusual noise or emission of excessive

smoke.

· There is an insufficient or excessive amount of oil in the engine or, low engine oil pressure, which

could cause engine damage if the engine is accelerated.

· There are obvious signs that the governors have been tampered with or are not operating.

· The vehicle owner / presenter cannot confirm that the vehicle has been properly maintained, the

camshaft drive belt has been replaced at the recommended intervals and the engine is in a suitable

condition for testing.

In the above circumstances where a metered smoke test is not carried out, the vehicle will fail the MOT test

I think that is the official wording :P

You certainly do. That told me

No worries on the Avant anyway mate..............