MOT Failure - Emissions

[Fast,not furious]

My S3 failed the MOT yesterday on the emissions test at slow and fast idle: the CO (carbon monoxide0) is reading 0.20%

It's been serviced recently too.

Audi say they tried everything,but couldn't get the figure down.

The car's Custom Code mapped,with sport CAT and C.A.I

Any ideas??

 

[Cyrix]

If it's passed an MOT before I would probably be looking at the exhaust, either the CAT itself or an exhaust leak post CAT.

 

[Fast,not furious]

If it's passed an MOT before I would probably be looking at the exhaust, either the CAT itself or an exhaust leak post CAT.

It passed no prob last year,hoping it's not the CAT!

 

[jungleman]

iffy set of plugs maybe?

 

[Fast,not furious]

iffy set of plugs maybe?

Maybe,worth a try!

 

[jungleman]

be the cheapest thing to try, they been in the car long?

 

[Fast,not furious]

About 25000 miles i guess?

 

[jungleman]

thats loads!!!!
they must be knackered by now!!

 

[Fast,not furious]

thats loads!!!!
they must be knackered by now!!

Is it? I thought they were good for 40k?...might be worth a shot then?

 

[jungleman]

maybe on a stock car, but yours is pretty heavily modified!! bet thats where your problem is!

 

[Fast,not furious]

Just having a look at the readout:

Fast idle test
Speed Not checked
CO 0.51%vol
HC 146ppm
Lambda 1.01

2nd fast idle test
Speed Not checked
CO 0.47%vol
HC 167ppm

Natural Idle test
CO 0.39%vol

Summary results

Oil temp 60
Fast idle test Fail
CO(0.20) fail
HC (200) pass
Lamb(0.97 - 1.03) pass

2nd fast idle test
CO(0.20) fail
HC(200) pass
Lamb(0.97 - 1.03) pass

Idle speed Fail
CO (0.30) Fail


Oil temp looks low to me,surely a better result would be obtained wit a hot engine?
__________

 

[Khufu]

TBH, we find that high lambda reading needs new lambda/oxygen sensor & high CO2 needs cat (or two in your case!!). The issue could then be the sport cat and how the map is written for it :-(

The oil temp isnt as crucial to that side of the test, more for the hydrocarbons. Its more important that the lambda sensor & cat are warmed up though usually a warm engine will mean a warm lambda & Cat.

 

[Fast,not furious]

TBH, we find that high lambda reading needs new lambda/oxygen sensor & high CO2 needs cat (or two in your case!!). The issue could then be the sport cat and how the map is written for it :-(

The oil temp isnt as crucial to that side of the test, more for the hydrocarbons. Its more important that the lambda sensor & cat are warmed up though usually a warm engine will mean a warm lambda & Cat.

The exhaust's only about 2 years old :-(

 

[Fast,not furious]

Sorted!!

I ran some Wynns Gold fuel cleaner through her,gave it the beans so she was nice and hot and had it MOT'd at my local Citroen dealership,very helpful! One set of new plugs on standby,just in case though.
Ok,so i couldn't take advantage of the free MOT at audi,but at least it passed!

 

[paddy]

How much better were the readings ?

My car failed the MOT 2 years ago at Audi's because of worn disc's....took it somewhere else and its been fine ever since. this year i asked them to check the disc's just in case and they said about 70% worn but fine for another year.

 

[FranA3]

i would be tempted to put a new set of plugs in there anyway as they have done alot of miles and are prob nackered by now