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MOT result - any explanation plse

My Rover 200 passed the MOT today but I'm interested in the emissions result.

Last year the Natural Idle test was run at 874rpm and returned a CO figure of .30%, spot on the upper limit.

This year, using the same test equipment and tester, it's described as a 'manual check' and returned a CO figure of just .08%.

I would say the engine was in a very similar state, with ignition components in good condition. The only difference is that I gave it a right good thrashing for about 40 miles last night, and about another 30 before delivering it to the Test Station. Could this account for the apparent improvement ?

If the test is this variable on a pretty similar engine, I wonder what it's worth ?

The previous Fast Idle test was run at 2789 and returned a CO of .14% This year again it was a 'manual check' and returned a figure of 0% !!

The other figures show an increase from 44 > 80 ppm HC and a lamda increase from 1.004 > 1.015

TIA Andy C

Reply to
Andy Cap
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Andy Cap gurgled happily, sounding much like they were saying:

Damn near a fail, then - way too high.

That's more like it.

That's irrelevant...

...but that's not.

Might just be that it wasn't up to temp fully last time.

It'll naturally move about a snidge, as it requires a move away from zero to tell it to adjust the mixture. Over 1 is slightly lean, under 1 is slightly rich. IIRC pass is 0.97 - 1.03

Don't sweat it.

Reply to
Adrian

Not necessarily, many MOT emission test equipment move onto the next phase as soon as a pass figure is registered.

But what is a "Manual Check" Normally a BET test, if that fails then a full CAT test. Manual Check implies checking the emissions at fast idle and natural idle but not following the preset procedure.

Reply to
Jimmy

Well the form said Limit =But what is a "Manual Check" Normally a BET test, if that fails then a

Yes, I'd like to know why a 'manual check' and no rpm figures. He's a VERY experienced tester, plus with centralised computer monitoring, I can't see anyone fiddling the test or perhaps they can ?

Reply to
Andy Cap

Jimmy gurgled happily, sounding much like they were saying:

It shouldn't be anywhere near that limit, though.

Problem with the equipment?

Reply to
Adrian

No emission figures are entered into the MOT computer but a printout should be given to the customer and a copy retained by the station for

3 months.
Reply to
Jimmy

Then the station should cease testing until its fixed.

Reply to
Jimmy

Nah, the tester's just *that* experienced that he just sticks his nose into the exhaust and breathes deep, then he knows the result - hence manual check :-)

Reply to
DanB

The manual check still uses the probe up the exhaust to check emissions but they havn't connected the RPM probe. Some cars don't have easy access to the ht leads without removing various engine covers so the RPM has to be manually checked.

Reply to
Redwood

Thanks for that. Funny that he took the trouble last year then. Must have been feeling lazy !

I'm still surprised that pre-warming the engine - I used to book the first appointment of the day and it's just across the road - but this time deliberately took it for bomb up the main road, made such a difference, because I don't believe there was much else different with the engine.

Rather renders the test a bit of a lottery, or did I miss an ealier point, that should this test fail, then they move on to a stiffer standard that it may well pass ? Just a bit puzzled really.

Andy C

Reply to
Andy Cap

ours & most of the new spec machines out there use the battery to detect the rpm, just hook it up to the positive & neg, so no need to use the HT leads, but as some batteries are in the boot of certain vehicles the leads wont reach or you have to dismantle half the car to gain access, then you do a manual check with the rpm from the rev counter.

Reply to
reg

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