Does anyone know how the MOT smoke test limits are applied to different engines? Are there different ones for different engines?
I ask as when my 2.1TD went through the MOT, it was subject to a smoke limit of 1.5 l/m. Xac recently had his 1.9TD MOT'd and he appeared to have been subject to a test limit of 3.0 l/m.
My 2.1TD passed at 0.03 l/m whereas Xac's passed at 1.92 l/m.
Now, had my 2.1TD, say, been fitted with a mechanical pump, as I would plan to do if the EPIC failed, it might well fail if the lower limit was applied.
So, are the older XUD9s and so on tested to a different limit than say, the later 2.1TDs and HDis?
Diesel Smoke Tests
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Diesel Smoke Tests
Jim
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Brilliant Will, thanks! Google never was my friend for finding stuff like that
All is now completely clear (no pun intended..) So if it's clean and passes at 1.5 l/m (Fast Pass) then fine. Otherwise it's tested at 3.0 l/m...
The engine will be accelerated up to governed
speed and the smoke density measured.
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.
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 is 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 vapour, to an extent likely to obscure vision.
Jim
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
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Re: Diesel Smoke Tests
That's a very good result Jim. I think some of the latest diesels with particulate filters would struggle to better that.citrojim wrote: My 2.1TD passed at 0.03 l/m
Mine was over the fast pass at 1.70 last time. Having said that I think my Xsara is a little smokey for an HDi. I've long suspected I have one injector on the way out.
My old Xantia 1.9TD was better, I think it used to average around 1.40 .
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I've read about the possibility of cam belt failure since this test was introduced. It doesn't seem to have caused too many problems.
Surely a turbo diesel (which almost all diesels are nowadays) won't be running much boost, since the engine isn't under load. So the cam belt is unlikely to break - in fact the pressure on it will be less than in a N/A diesel because of the reduced compression ratio on the turbo engine. Will somebody please tell me why I'm wrong?
James
Surely a turbo diesel (which almost all diesels are nowadays) won't be running much boost, since the engine isn't under load. So the cam belt is unlikely to break - in fact the pressure on it will be less than in a N/A diesel because of the reduced compression ratio on the turbo engine. Will somebody please tell me why I'm wrong?
James
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