Technical mk 2 punto emissions failure

[TONY55S]

hi,
my 2000 reg punto failed emissions test today.
The results were high idle 2770rpm CO 0.50 vol%
Anything above 0.30% is a fail.
Is it worth changing the lamba sensor?
i have been getting a misfire now and then ,but then it clears
any ideas before i scrap the car?
tony

 

[Joao Gomes]

What engine has it got?

 

[TONY55S]

its 1.2 8 valve

 

[TONY55S]

Also i have to keep topping the car up with engine oil recently.
Would this be a sign of worn guide valve seals?
tony

 

[Joao Gomes]

Also i have to keep topping the car up with engine oil recently.
Would this be a sign of worn guide valve seals?
tony

Perhaps. But that depends if there's any other visible oil leaks

 

[Joao Gomes]

Have you tried some fuel system cleaner down it's tank and ran it

 

[TONY55S]

I am fairly sure its the intermittant misfire that is causing the emissions to fail.
I have changed leads,coil pack ,plugs,and the fact the car is using oil leads me to think something in the engine has worn out since it has 150k miles done.

 

[Brendan W]

What do the plugs look like?

 

[TONY55S]

I removed all 4 plugs last nite.
Starting from the left side of the engine as you look in,
the first 2 plugs were a dry whitish colour,and the last 2 were fairly black
with bits of soot which i cleaned off.
tony

 

[TONY55S]

The car passed the co on low idle,but failed on high idle.

 

[Brendan W]

Might be worth swapping the injectors from that side to the other and see if the plug colour moves. As mentioned already a bit of injector cleaner could help.
If it was worn out I would expect the black plugs to be wet rather than dry.
A compression test would be the next thing to try.