Just to say hi fellow s3 owners, and need some advice on emissions/ Lambda sensors

[s3jon92]

So Ive been a member of audi-sport for a while now and thought its about time I said Hi!
Firstly, what a great forum! I joined it whilst looking for an S3 and its been great help ever since. Some brilliant advice on here and inspiring builds.
I picked up my AMK s3 exactly 6months ago and absolutely love it! Heres a pic of her when I first got it:

[SUP] [/SUP]

Since owning the car Ive done a few subtle mods like wrapping the grill surround and the lower door blades, Ive had it on the dyno and despite having 175000 miles its still got near enough its factory power! Ive been hit by a pr*ck romanian lorry driver and been declined anti corrosion warranty at coventry audi Ive also recently done a full service including removing the sump and replacing the pick up pipe (thanks for the excellent, in depth how to's!) Theres plenty more Id like to do but probably best to get eduacation out the way first and get some proper funds in :/

Anyway last week I took the car in for its MOT, it passed everything bar the dreaded emissions! Ive done the complete service, put a bottle of cat-a-clean through the system and got it nice n hot but still no luck. these are the results:




If the car is revved hard the CO emissions drop to under the pass percentage but dont stay there for long before climbing again.
Its not displaying any faut codes on the diagnostic machine and the engine management light isnt on. Both the Lambda sensors are recieving a voltage from the ecu but dont appear to be adjusting the fueling :s the heater element is on- off on the pre lambda but occasionally flickers on the post lambda.
Im a bit stumped now whether to replace the cat, pre or post lambda or the whole lot?
If anyone has any ideas theyd be much appreciated!
Many thanks,
Jon

 

[BRG_GTI]

Not much of a help but - I had a similar problem with my S3 recently when it failed on emissions.

I bought some fuel cleaner did a full service on her took it back to the garage and still failed.

I left the car with the garage when I picked the car up the mechanic was not there only his misses and the paperwork I got said cleaned air sensor.

After cleaning the air sensor it passed straight away.

 

[<tuffty/>]

What scanner you using? can you scan for fault codes in VCDS and do some logging of blocks? lambda control doesn't kick in until as certain temp... block 031 for requested lambda vs actual, block 001 for lambda control and have a look at block 032 for fuel trims....

Could be you have an air leak or something thats throwing the fuelling off its stride hence running over..

<tuffty/>

 

[Vex182]

When my car failed my emmisions it was down to a coilpack that was *breaking down* car drove normally with an idle that was always perfect too. Never noticed until the garage swapped 1 over, no codes in VCDS at that point too - think it was a weak spark. I think an air leak is more likely though to be honest so it's running rich.

 

[s3jon92]

Thanks guys, it seems I desperately need to get vagcom, would I be able to do the scans and logging with the free, lite version?
Ive cleaned the MAF sensor and the inlet temp sensor today, they were both black but still no luck with emissions. Ive been using the college's 'Gutman Mega Macs 50' diagnostics machine, its new but pretty awful software tbh. can anyone recomend someone in the Leamington spa, Midlands area I could go to with VCDS?
Using the diagnostics machine I can see the pre lambda doesnt seem to work in closed loop, but im not sure if this is cos the cat is dead or the pre lambda?
how would i go about checking for an air leak? visually the exhaust seems ok and i havent noticed a boost leak at all?
Jon