Technical MOT - Smoke - DPF

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Technical MOT - Smoke - DPF

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Well it was a good news day today. Another MOT done and dusted.

However I notice something interesting in the emissions test results.

Smoke Test:

2009 - 0.03 limit 3.00
2010 - not recorded
2011 - 0.02 limit 1.5 (used to be 3.00 - ????)
2012 - 0.17 limit 1.5
2013 - 0.07 limit 1.5
2014 - 0.45 limit 1.5 (big jump)

Now ignoring equipment calibration or fault errors and average figure of 0.10 or less this year jumped to 0.45.

I also made a post some time ago about seeing white smoke & smell on cold/first start.

So I'm wondering if my DPF filter is slowly degrading as in the inner core is disintegrating (now 9 years old). I've never kept a track of DPF regeneration statistics so am unable to say if the regens are less frequent than in the past which would also suggest an internal degradation.

The other point that *isses me off. If when I bought my car brand new in 2006 and tested to MOT regs 3 years later only had to beat 3.00 why is it now 1.50? Talk about goal post moving.

And on goal post moving I never did get a response from VOSA as to why a fully legally homologated Euro IV diesel car (where no DPF required) is now tested (all be it visual) to Euro V regarding DPF removal/presence.

I do notice that these politicians drive tax payer funded diesel limos (POLUTING according to the gov) and they get new cars every few years so probably non of them get to MOT time.

Hats of to Borris (and some others) who vote with their feet on the pedals. Their emissions are of a different nature and only subject to voter's votes :D
 
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Perhaps the inlet manifold is starting to get blocked up on the swirl flap side due to the crap out of the egr.
 
As far as I can tell my swirl flaps have not worked for many a year, if ever. Having said this I'm not sure why swirl flaps (working or otherwise) would potentially affect the MOT smoke test. Not saying they could or couldn't but just thinking the "intake system" (which includes EGR modulated) is pretty much a closed and regulated system. The pollution/soot that comes out via the exhaust manifold, via turbo or EGR gets ingested and spat out again with a percentage going back through the EGR loop again.

The MOT test data cited would suggest that the DPF (which is after manifold, turbo, EGR) is filtering out less particulates as time passes by.

Maybe my car is self removing it's own DPF just to wave a finger at the UK/EU bureaucrats ? ! :)
 
I think you,ve answered your own question.The dpf is filtering less.Maybe because its getting blocked partially.If the swirl flaps are working they open another inlet port in the head,for the other inlet valve.Perhaps over time this would point to it running on one inlet valve per cylinder with the swirls inoperative and thus a gradual decline in effective smoke readings.just a thought.
 
I think you,ve answered your own question.The dpf is filtering less.Maybe because its getting blocked partially.If the swirl flaps are working they open another inlet port in the head,for the other inlet valve.Perhaps over time this would point to it running on one inlet valve per cylinder with the swirls inoperative and thus a gradual decline in effective smoke readings.just a thought.

If the DPF was getting more clogged then I would expect it to trap more and also performance to decrease, excessive regen times and ultimately an ECU error for clogged filter. None of this is happening.

As for swirl flaps. Their proper mode of operation is as follows:

1) Fully open (i.e. two ports unblocked) with engine off as is not running. Ignition can be on or off

2) As soon as engine starts the flaps close to restrict one port on each cylinder and increase air flow into combustion chamber

3) From idle rpm to 2K rpm (2K if I recall correctly) then engine ECU modulates the flaps base on rpm and engine load.

4) Above 2K rpm the flaps are fully open.

On my car they are fully open all the time.

The inoperative / neutral position for the swirl flaps is fully open.
 
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