Ford Focus emissions

[dilateous]

MOT HC emissions reading for my 2011 Ford Focus increased every year, to the point that I concluded there's a good chance it would fail this year. Much to my surprise it was lower this year (132 to 76)! All I did was replace the air filter and close up the plug gap a touch - and I mean a touch. The only other difference was a different tester (same garage).

I'm surprised if it was just air filter or plug gap. I didn't think the old filter was that dirty. For information please find picture of old and new filter attached. Although it was a Ford spare, it may be noticed that the new filter is slightly larger than the old one.

Anyway, thought this info might be useful - if not thought provoking!

[steveo3002]

was it tested in the same conditions ? maybe one was freshly started and the other had been on a good run before and fully up to temp

[dilateous]

It was done at the same time of day (08:00hr), with what I estimate to be the same amount of engine run (the distance between home and garage). And as for ambient temperature, from recollection, I'd judge to be the same.

From 132 to 76 is a significant difference I'd say, which from my perspective, I can't account for.

I might add that all the other readings have always been well within limits for all tested years.

Perhaps the test equipment has experienced a change - serviced, parts changed, recalibrated or something.