MOT Test - CO Query

[blu_s2]

Had latest MOT done yesterday (95 ABY)

All went through okay, wasn't till I got home that I read the emissions results which gave me one concern.

At fast idle the figures were excellent with *very* low CO (0.03 from memory) and HC levels.

However, on normal idle the CO was high at 0.47 (limit 0.50). This is much higher than last year (which was <0.1). HC was very low as well.

Any ideas as to what may be causing this problem at low revs?

Cheers

PS Lambda was 1.01 and engine well warmed up beforehand.

The lamda probe was replaced around 20k miles ago.

[Dr H]

Jim

When I put mine through an emissions test without the CATs it was the CO levels that failed it. The HC were below the pass levels.

Once the CATs were back on the CO and HC levels dropped massively

CO Levels were

Fast idle 0.03 (with) 0.97 (without)

Nat idle 0.00 (with) 0.69 (without)

Not sure but maybe you CATs are on their way out mind you not sure why they would only be affected at low revs.

What mileage is on your car now?

[blu_s2]

59k

[Dr H]

Hmmm same milage as mine. My CATs play up when it is really hot weather (mysterious smoke that noone has solved yet) but they seem to work OK emission wise.

Your not getting any smells from the CATs are you?

Maybe you are right about the lambda - could the car be running too rich at tickover? This might give high CO values

[Ski]

on my old 80, i did a custom job, missed out the cats and middle box.

it would never pass in million yrs so i just found myself a bent station to do me MOT's for £60 without even seeing my car.

was cheapest option as each cat came to £600 or so.