Emmisions - 1.4 TDI - CT (MOT) Fail Yesterday

[JWT]

I took my A2 for its CT yesterday which is only every 2 years in France. It would appear that the threshold for the emmision test has been changed since my last CT for this car.
I guess the question I am asking is what is the real life emmision level result that can be expected from the 1.4TDI 75 - whatever I do it may mean that the car will not pass - the accpeted level being less than or equal to 0.70m - the car achieved an average of 2.03 at the test.
Could anyone confirm the UK MOT test requirements ?

 

[Dubdriver]

It also just occurred to me- what actually is being measured to generate the torsion value number? Is it the timing relationship between crank and cam? If it is, it then assumes that the crank and cam sensor mountings are ridiculously accurately milled into the castings. And that the two sensors are really really accurate, and consistent with no measurable variance between production batches. I'm shaking my head. Nah, not possible...

 

[Guest 4123]

Messing around with the torsion value would involve a whole lot of trial and error (mainly the latter) and does have its risks. Have the injectors been examined for wear?

RAB

 

[Dubdriver]

Yeah, brand new or completely scored and worn out injectors- exact same effect. Smoke and emissions drastically affected by this torsion value. From my observations, as smoke goes up, NOX goes down and vice versa. I adjust for max Nox. Max efficiency. Londoners hate me. Acid rain etc...

(As an aside- Actually, you can measure injector wear, as the ecu is smart enough to compensate for wear and uneven injection quantities between cylinders.)

 

[kraig22]

Yeah, brand new or completely scored and worn out injectors- exact same effect. Smoke and emissions drastically affected by this torsion value. From my observations, as smoke goes up, NOX goes down and vice versa. I adjust for max Nox. Max efficiency. Londoners hate me. Acid rain etc...

(As an aside- Actually, you can measure injector wear, as the ecu is smart enough to compensate for wear and uneven injection quantities between cylinders.)

If you look into the the t4 2.5 tdi pd there is a lot about it . As the injector timing is adjusted by rotating the fuel pump pulley . Which In turn adjusts the injector quantity as it open the spill collet inside the fuel pump earlier which gives you less or more fuel per revolution.
Had to sort my t4 as the belts stretch giving you worse feeling over time. 3pot pd engines have fuel pump running direct from the cam. So not so much info but same situation.