MOT failed on emissions

GeX · 22 Jan 2011 at 16:30

Hi all.

Took the Xsara VTS in for an MOT today, it failed on the emissions test. Excessive CO and low lambda on the fast idle test.

Idle Test;

CO = 0.482% (pass, limit 0.5%)

Fast Idle Test;

CO = 2.158% (fail, limit 0.3%)
HC = 108ppm (pass, limit 200ppm)
Lambda = 0.942 (fail, range 0.970-1.030)

2nd attempt;

CO = 2.041% (fail, limit 0.3%)
HC = 86ppm (pass, limit 200ppm)
Lambda = 0.930 (fail, range 0.970-1.030)

So even at idle, it was high and it's failing on fast idle by a LOT over on the CO but HC seems fine.

I have noticed some 'odd running' issues as of late, and suspect they are all connected.
From to time to time, when pulling up to a stop - the revs will not fall to idle and instead sit at ~1500rpm. A quick rev cures this and it'll then sit and idle at around 850rpm.
If I take my foot off the accelerator coming down a hill, or slowing at to a stop (so the car is still in gear) with the revs at around 2k rpm instead of the engine just pulling the car along, it'll surge. Not violently - but it doesn't seem right at all.

Any ideas folks?

4T5 · 22 Jan 2011 at 16:32

Just sounds like it needs a decent service to me.

GeX · 22 Jan 2011 at 16:33

Forgot to add, it had new plugs, oil and filters around 2000 miles (3 months) ago.

4T5 · 22 Jan 2011 at 16:36

Needs plugging in then.

Rich1988 · 22 Jan 2011 at 17:51

lamda sensor sounds like, will cause lumpy idle and acceleration issues and will cause high co reading,

was the car lovely and hot when you ran it through emissions (i.e it had just been out and had a spirited run)

Fuzz · 22 Jan 2011 at 17:56

Rich1988 said:
lamda sensor sounds like, will cause lumpy idle and acceleration issues and will cause high co reading,

was the car lovely and hot when you ran it through emissions (i.e it had just been out and had a spirited run)

This..

GeX · 22 Jan 2011 at 18:02

It's more deceleration issues, but yes the car was nice and hot when I dropped it off (engine and oil temps at middle of the gauges, just been for a blast up the motorway)

Rich1988 · 22 Jan 2011 at 18:42

mine failed the first 3 tests, took it out and really gave it stick tested it straight away and it passed, I had all the other issues you describe, (surging on deceleration and under slow acceleration, lump idle not such amazing fuel economy etc).

d/ced the lambda and all the obvious symptoms dissappeared.