MOT failure on emissions-then passed.cars runnin great

[martint]

my car(406 hdi 90) failed its emissions test yesterday.my car has been really smokey when puttin foot down etc.
the mechanic/mot tester said not to worry.he ordered a bottle of metatec i think it was called,then poured some into fuel filter & rest into tank.he then told me to take it for a run and to really blast it-ie 45 in 3rd gear etc.
i said i couldnt do that but could he,as it just wouldnt feel right thrashing my beloved 406.
anyway,i returned to pick car up 1hr later and it'd passed its emissioms/mot ,but when i drove it away i was shocked-it drives really faster now & no smoke no matter how hard i drive it!also my consumptions just got better as well 51.2mpg around town.
its like its a different engine-more responsive as well,even for a diesel!
what you all think? mot tester said it couldve been injectors etc all shitted up plus unburned fuel due to this

[poddack]

Sounds about right, some redex or the like into the tank/fuel filter and a good old Italian tune-up before every MOT.

[trem1]

in the past with older transits, we had a driver who just pottered around and his van was terrible to drive for the first hour or so of driving it :low on power LOADS of black smoke etc but after awhile it cleared and was the same as the rest :ie no smoke from exhaust etc.
i think diesels work better if there worked properly (NOT trashed) but worked quite hard, if you understand me

[Doggy]

I'd agree with you there - my dad used to look after a fleet of diesel shunting locos. The ones that sat idling for hours to keep the heaters working would eventually stop altogether, so coked up the exhaust ports had virtually no opening left.

[Bailes1992]

Diesels have to be worked hard to keep them 100%
Once in a while just take it through the gears upto 4,000revs in each gear, wont do it any harm!

Pottering about in diesels really screws them up!

[martint]

bailes thats exactly what the mechanic said as well.
he said most hdi's & some tdi's need to be driven quite hard from time to time!
if any o you guys got plenty dirty smoke etc , & lack o response, lag etc, might be worth giving your car a bottle o that axybutethylene or whatever. cant believe difference now.

[Bailes1992]

Don't really need the bottle of additive. Stuck 250mls of two stroke in with every full tank of diesel and once in a while just give the car a good workout, will thank you for it

[ally406]

Agreed, it's not good to nanny the engine, it's actually bad for it! The engine oil also absorbs moisture over time, giving a damn good thrashing now and then gets the oil good and hot and makes it evaporate. You may notice that if you pop your oil filler cap off after a hard run you might have a little bit of steam coming out!

[Bailes1992]

Best way to look after 406 diesels (XUD and HDi) is to switch them on and leave them idle for a minuite to get abit of heat in the oil and make sure theres oil everywhere and good pressure is built.
Then keep them under 2,000rpm maybe 2,500rpm up hills until it's warm. When it's hot drive between 1,700 and 3,000rpm. Rather than use your right foot to push you along use the revs. When your higher in the revs you need less movement of the throttle to push you along. It sounds daft I know but try it! Will make sense. You also stop engine labouring at any time, you keep the engine nice and hot and you should get better economy.
Then once in a while, maybe at traffic lights in a national road or when a 30 road goes into a national road or even on the slip road onto the motorway just give it the beans in every gear, but only when it's hot!
When you go to turn the engine off keep the revs low for the last mile of the journey and just let it idle for 30s before you actually switch it off to make sure the turbos spooled down.

Change the oil every 6,000miles at most with general 10w40 Semi synthetic oil. Stick 250mls of two stroke in with a full tank of diesel (Lubricated the pumps, injectors and cylinders. Ups the cetane rating and lets the engine run quieter, smoother and less smokey) and bobs your Uncle

[rwb]

There's a difference between thrashing it and working it.
With this in mind I did 80 (at 2900rpm) on the M4 on the way back from Henley today, and I'm sure it feels a bit better for it.

(Couldn't do it on the way there as I got engine anti-pollution system defective just as I turned onto the slip-road at J10 )