Fluctuating Co At Idle

[Bogsye 22]

My car has just failled it's MOT on CO at idle. I've read the other topics and adjusting the mixture screw AFM seems the way to go, however, the tester did note that it seems to have a fluctuating CO level, as it's sometimes in spec and then rises to a heady 6.96%

HC sits at 289ppm so it's okay.

 

I'm guessing that it could be a temperature sensing related issue and it's bringing itself onto choke even when it's warm.

 

I should have seen this coming as it idled at 1800rpm when I got it and it seemed to easy to fix that by adjusting the idle back down

 

Any ideas?

 

My other fail items are easy, and my tester is a pretty decent guy, although I was suprised he didn't try and charge me a for a new ribbon for his fail notice printer.

 

Mind you, two weeks to get it together to avoid a re-test fee ain't long.

 

Brian.

Edited May 22, 2009 by Bogsye

[2-Pugs 57]

My 205 failed the mot just the other week for exactly the same reason and strangely enough I also had a CO level of about 6.5%. Upon the advice of the mot tester I fitted a new lambda sensor (which you'll ony have if you have a cat) and engine temperature sender.

 

Went back the next day and the emissions were well below the 0.5% limit. Amazing, i could hardly believe it.

 

So anyway - if I were you - change the temp sender (only about 18 quid from a factors, or about £21 from Peugeot I think), and it takes less than an hour to change although it helps if you have a deep socket to remove it.

[Bogsye 22]

My 205 failed the mot just the other week for exactly the same reason and strangely enough I also had a CO level of about 6.5%. Upon the advice of the mot tester I fitted a new lambda sensor (which you'll ony have if you have a cat) and engine temperature sender.

 

Went back the next day and the emissions were well below the 0.5% limit. Amazing, i could hardly believe it.

 

So anyway - if I were you - change the temp sender (only about 18 quid from a factors, or about £21 from Peugeot I think), and it takes less than an hour to change although it helps if you have a deep socket to remove it.

 

Thanks 2-Pugs, I'll give the temperature sensor a shot and see where that takes it. That and a bit of adjustment might just sort it out.