Nissan Micra K11 - MoT emissions failure - mikem004

2001, 115k miles.

Just failed MOT emissions test, due to high CO at idle. A complete surprise as the car seems to run well.

Garage hooked up a code reader. No faults reported.

Garage changed spark plugs, no improvement.

Problem identified as caused by "shagged" timing chain. Repair could be uneconomical.

I have a couple of questions before I scrap the car:

1) Timing chain has been noisy when cold for the past 2 years. But this is usually cured by an oil change...is it worth trying this + a retest?

2) I thought timing chains would last the lifetime of the car?

Nissan Micra K11 - MoT emissions failure - mikem004

Idle CO was 0.6. Maximum allowed is 0.5.

All other emissions were OK.

Nissan Micra K11 - MoT emissions failure - madf

Micra timing chain is a known weakness - aggravated by late oil changes/poor oil/not enough oil.

Try a good injector cleaner (Forte?) and a prolonged Italian tune-up after cleaning EGR valve - if it has one.

Nissan Micra K11 - MoT emissions failure - elekie&a/c doctor

Emission failure here is marginal.I doubt if a worn timing chain is the problem.I have seen plenty of k11 micras with engines that sound like a tin of nails and they still pass the test.I'm with mr madf .Injector cleaner and then a heavy right foot.hth

Nissan Micra K11 - MoT emissions failure - mikem004

I wouldn't mind betting that it would pass OK after an oil change. The idle is so much smoother.

But I'm worried about throwing good money after bad. I've already shelled out 40 for the MOT, plus 60 in "diagnosis" and labour charges.

Nissan Micra K11 - MoT emissions failure - bathtub tom

What about the air filter? May be worth taking it out along with the suggestions above?

Thermostat? What temperature does it run at? Could the injection be fuelling it rich because it's running cool?

Nissan Micra K11 - MoT emissions failure - unthrottled

It won't be the air filter-the air clogged air filter=over rich mixture problem died with carburettors.

Nissan Micra K11 - MoT emissions failure - Oli rag

I think I'd change the oil and stick it back in, it was only a marginal fail.

 

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