Emmisions - 1.4 TDI - CT (MOT) Fail Yesterday

J

JWT

Member
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 ?
 
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JWT said:
Just a quick update the A2 has returned to the UK - and guess what has flown through the MOT !!!! Now awaiiting re registration with the DVLA once HMRC have cleared the car.
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That's good news!
What was the smoke test reading for the UK MOT?
Perhaps the drive from France cleared it out sufficiently to get below the required figure.
 
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Skipton01 said:
Is it right that the government can retrospectively change emissions levels? I'm all for cleaning up the atmosphere and lowering pollution, but it's not right to expect a 20 year old car to be able to pass modern standards - if they continue to pass the standards that were in place at the time they were first tested, that should be sufficient.

And don't get me started on the 'new cars are better for the environment' argument - it's been well proven that a well-maintained classic is just as 'good' for the environment as a brand new one (possibly even EVs). The best car for the environment is no car!
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I think that the OP is implying that the emission standards required are different between England and France, which of course, shouldn't be the case.

RAB
 
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No, the first post is quite explicit:

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.

This is from a French member who is comparing their most recent test to their last one. I really don't think it's understandable in any other context. Yes, they go on to ask about UK levels for A2 diesels, but the statement which opens the thread implies that France is in some way lowering emissions levels to possibly legislate older cars off the road.
 
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Skipton01 said:
Until the levels are lowered again!
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what as happened is the French have started to check against the 'plate value' on the car. The UK mot also does exactly the same, except the UK mot test as a loop hole in that if the plate cannot be found / is no readable then there is a set of limits which are based on age of car. for the A2 this limit is 3.0
The plate value on the A2 TDI's varies slightly by engine type, the AMF is (from memory 0.8) the BHC/ATL is 0.7

So, the French test is only checking against the plate (no option to use the higher age related values) I suspect that two years ago on the last CT test it was checked agasint the age related 'can't find the plate' value of 3.0
The uk mot was broadly in line with the EU tests before Brexit, it will no doubt gradually diverge as time passes.

Cheers,
Paul
 
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depronman said:
what as happened is the French have started to check against the 'plate value' on the car. The UK mot also does exactly the same, except the UK mot test as a loop hole in that if the plate cannot be found / is no readable then there is a set of limits which are based on age of car. for the A2 this limit is 3.0
The plate value on the A2 TDI's varies slightly by engine type, the AMF is (from memory 0.8) the BHC/ATL is 0.7

So, the French test is only checking against the plate (no option to use the higher age related values) I suspect that two years ago on the last CT test it was checked agasint the age related 'can't find the plate' value of 3.0
The uk mot was broadly in line with the EU tests before Brexit, it will no doubt gradually diverge as time passes.

Cheers,
Paul
Click to expand...
Any ideas as to why these engines have gone from 0.7/0.8 when new, to >3.0 now?
Will a remap take them back to 0.7/0.8?
Mac.
 
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PlasticMac said:
Any ideas as to why these engines have gone from 0.7/0.8 when new, to >3.0 now?
Will a remap take them back to 0.7/0.8?
Mac.
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thay have not gone to 3.0 just the testing value (pass / fail) is 3.0 if the plate cannot be found by the mot tester
engines from different manufactures would all have been different values and it is this value which is stated on the plate, hence this is what the car 'should' be tested to as per the manufacturer, hoever plates get damaged/removed/can't be found so the UK MOT as a get out of jail cars which states that for the ago of the A2 3.0 can be used in the absence of the known plate value

as the engine wear it will gradually get worse on the smoke test from new
a remove can improve this, particularly if the EGR is made none operative as this wil reduce the particulate emmisions and this alone is what is tested on the MOT test.
It will however increase nox, but the general rule of thumb is the EGR is doing little to reduce nox past 50K miles and there fore it is a case of choose your poison. I know which way I would go

Paul
 
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depronman said:
thay have not gone to 3.0 just the testing value (pass / fail) is 3.0 if the plate cannot be found by the mot tester
engines from different manufactures would all have been different values and it is this value which is stated on the plate, hence this is what the car 'should' be tested to as per the manufacturer, hoever plates get damaged/removed/can't be found so the UK MOT as a get out of jail cars which states that for the ago of the A2 3.0 can be used in the absence of the known plate value

as the engine wear it will gradually get worse on the smoke test from new
a remove can improve this, particularly if the EGR is made none operative as this wil reduce the particulate emmisions and this alone is what is tested on the MOT test.
It will however increase nox, but the general rule of thumb is the EGR is doing little to reduce nox past 50K miles and there fore it is a case of choose your poison. I know which way I would go

Paul
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Thanks for the explanation.
Mac.
 
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My experiments on vdub pdi diesels and with my local MOT place has shown something interesting that i don't fully understand...
Fact: The ecu controls injection timing (start and finish).
But if the injection cam lobe (whole camshaft) is advanced a fraction, like a degree or two, the smoke emissions fall off a cliff. Retard the cam, the smoke goes up. I can't get my head around that, as injection timing can't be changed (it's set by the ECU).
Any ideas what's going on? I can't see why moving the position of the plunger incline (by moving the cam), would in effect advance the injection point.
On VE pumps, it's the same, even though on injector 3 (on 4 pots), there's a sensor to detect and close the injection-start-point loop. As the revs go up, the cam inside the VE pump is rotated a bit by a pwm solenoid to advance the start point of injection. Turn the VE pump slightly more advanced, smoke falls off a cliff again.
Bizarre... i must be missing something.
 
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Dubdriver said:
My experiments on vdub pdi diesels and with my local MOT place has shown something interesting that i don't fully understand...
Fact: The ecu controls injection timing (start and finish).
But if the injection cam lobe (whole camshaft) is advanced a fraction, like a degree or two, the smoke emissions fall off a cliff. Retard the cam, the smoke goes up. I can't get my head around that, as injection timing can't be changed (it's set by the ECU).
Any ideas what's going on? I can't see why moving the position of the plunger incline (by moving the cam), would in effect advance the injection point.
On VE pumps, it's the same, even though on injector 3 (on 4 pots), there's a sensor to detect and close the injection-start-point loop. As the revs go up, the cam inside the VE pump is rotated a bit by a pwm solenoid to advance the start point of injection. Turn the VE pump slightly more advanced, smoke falls off a cliff again.
Bizarre... i must be missing something.
Click to expand...
Does it possibly build the pressure earlier, so that when the ecu fires the injector the combustion is just slightly more advanced Maybe?
 
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I'm no expert on diesels, but, diesel engines smoke when the combustion efficiency is low, so unburnt fuel is sent into the exhaust system. Poor or incomplete combustion will also mean high fuel consumption and power loss.
So, although the ECU controls the point at which the injectors opens and close, varying the centre point of the pressure curve, (pressure is not constant, due in part to the cam shape), during the injector open period, relative to the piston position, will deliver the optimum volume of fuel and air, to match the compression pressure. This, in turn, will optimise combustion.
It's also likely that modern diesel fuel has different combustion characteristics to that of a decade or two ago, (low sulphur etc), so what was right then may not be now.
This may be absolute rubbish, I'm sure I'll soon find out.
Mac.
 
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We have lived in France 5 years now and registered the A2 here soon after we arrived. The CT (MOT) test value when we arrived was 3.0 a couple of years later 0.8 then to this CT it was 0.7 - the plate value of the car. Quite possibly a strategy to get older cars off the road but when you see some of the cars over here running around you wonder !!!
This car was on the VAG Heritage fleet for many years - came out for an MOT - passed each year - but it never has been at the magical 0.7 required now by the French system.
The A2 is now back in the UK - passed an MOT with no advisories - and is waiting to go back onto UK plates. We unfortunately cant just bring it back and use it like that as now post Brexit if your main residence is here then you have to have a French Reg on the car and if not its fine time (Euro 600) locally or more likely at the border - another Brexit Bonus !!!
 
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JWT said:
We have lived in France 5 years now and registered the A2 here soon after we arrived. The CT (MOT) test value when we arrived was 3.0 a couple of years later 0.8 then to this CT it was 0.7 - the plate value of the car. Quite possibly a strategy to get older cars off the road but when you see some of the cars over here running around you wonder !!!
This car was on the VAG Heritage fleet for many years - came out for an MOT - passed each year - but it never has been at the magical 0.7 required now by the French system.
The A2 is now back in the UK - passed an MOT with no advisories - and is waiting to go back onto UK plates. We unfortunately cant just bring it back and use it like that as now post Brexit if your main residence is here then you have to have a French Reg on the car and if not its fine time (Euro 600) locally or more likely at the border - another Brexit Bonus !!!
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If you wish to continue using your car in France as you have been doing for several years I do not understand why you simply do not liaise with Paul (Depronman) to have the his remap (post #25). This can be achieved via a postal service of the ecu or as the car is in the UK an arranged visit to sunny Blackpool. Seems to me far better to avoid the faff and expense of swapping to UK plates (+ associated angliasing work?, RHD headlights, MPH dash?????) and everything is sorted for the future in France.

Paul is well respected with extensive knowledge of the A2 in general and remapping.

Andy
 
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PlasticMac said:
I'm no expert on diesels, but, diesel engines smoke when the combustion efficiency is low, so unburnt fuel is sent into the exhaust system. Poor or incomplete combustion will also mean high fuel consumption and power loss.
So, although the ECU controls the point at which the injectors opens and close, varying the centre point of the pressure curve, (pressure is not constant, due in part to the cam shape), during the injector open period, relative to the piston position, will deliver the optimum volume of fuel and air, to match the compression pressure. This, in turn, will optimise combustion.
It's also likely that modern diesel fuel has different combustion characteristics to that of a decade or two ago, (low sulphur etc), so what was right then may not be now.
This may be absolute rubbish, I'm sure I'll soon find out.
Mac.
Click to expand...
Thinking about it, changing the mapped timing of the injectors open/close sequence, would have the exactly same effect as tweaking the pump cam.
Note: I'm not advocating any of this, just curious, and interested in the hows and whys.
Mac.
 
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The remap has already been completed by WOM in September in conjunction with Depronman - it worked extremely well and the economy improved to 67 mpg on the run back to France - unfortunately the emission test best was 1.07 - still not low enough to pass the CT at 0.70.I have had no other option than to return the car to the UK and as stated and it has passed the MOT with not a single advisory !!!
 
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Was the torsional value checked using vcds?

My understanding (although not personally tried this) is that very small adjustments of this TV results is major reductions in the smoke produced and this is what the mot test measures
In theory it is meant to read 0.0 but there is a tolerance and small adjustments are meant to increase or decrease the smoke generated

This is also meant to be able to ‘tune’ the engine for either performant or economy

I don’t believe Audi support this ‘adjustment’ but they do provide a slotted cam belt wheel that allows the adjustment to be made and vcds provides the TV measurement block

Paul


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depronman said:
Was the torsional value checked using vcds?

My understanding (although not personally tried this) is that very small adjustments of this TV results is major reductions in the smoke produced and this is what the mot test measures
In theory it is meant to read 0.0 but there is a tolerance and small adjustments are meant to increase or decrease the smoke generated

This is also meant to be able to ‘tune’ the engine for either performant or economy
Click to expand...

Yes, changed from +0.6 to 0. That's when I starting getting curious...

The question still remains... What actually happens when you either rotate (advance) the cam (or the VE pump)?

I have a theory, but no proof. Could it be that as the roller follows the (injector) cam profile, the plunger on the injector will be further in, on its down stroke? In effect any slack has been taken out (there's always some slack, as you need to back off the nut on the end of the rocker arm- the one on top of the injector). But... it shouldn't make any difference because the injection timing is controlled by the ECU. Or maybe the ECU actually has no idea where on the cam profile the injector is, as it's all based on static setup. Or maybe, the pressure doesn't start building inside the injector until the plunger has moved down a bit already? I just don't know. @RAB knows this stuff... :)

I once read on another forum that the "perfect" torsion value for each unique engine is written in black pen inside a white box on the barcode sticker, stuck on the upper cam belt cover. There have been many debates about torsion value, nothing conclusive though. I'm still learning!
 
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Dubdriver said:
Yes, changed from +0.6 to 0. That's when I starting getting curious...

The question still remains... What actually happens when you either rotate (advance) the cam (or the VE pump)?

I have a theory, but no proof. Could it be that as the roller follows the (injector) cam profile, the plunger on the injector will be further in, on its down stroke? In effect any slack has been taken out (there's always some slack, as you need to back off the nut on the end of the rocker arm- the one on top of the injector). But... it shouldn't make any difference because the injection timing is controlled by the ECU. Or maybe the ECU actually has no idea where on the cam profile the injector is, as it's all based on static setup. Or maybe, the pressure doesn't start building inside the injector until the plunger has moved down a bit already? I just don't know. @RAB knows this stuff... :)

I once read on another forum that the "perfect" torsion value for each unique engine is written in black pen inside a white box on the barcode sticker, stuck on the upper cam belt cover. There have been many debates about torsion value, nothing conclusive though. I'm still learning!
Click to expand...
Yes I’ve seen the claim about the correct TV value being handwritten on the cambelt cover - mine is illegible however because whoever wrote it had bad handwriting!!
 
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