Failed NCT on emissions, low idle only - recommend an Audi/emissions mechanic in Dub?

Lochaber

Hi all,

Have never had a car fail on emissions before and I was hoping that I might get some advice ... it's a 2002 Audi A3 with approx 51,000 miles on it.

Here are the figures:

Engine/Oil temp: 104 degrees
Low idle (702 rpm)
CO: 0.81 vol% (should be below 0.30%)
HC 135ppm (should be 0ppm)

High idle (2962 rpm)
Lambda: 1.00 (should be between 0.97 and 1.03)
CO: 0.05 vol% (should be below 0.20%)
HC: 61ppm (should be below 200ppm)

So it only failed on the CO/HC at the Low Idle... but I have no idea what that means, or even if those figures are very high or not.

Can someone help me out here? Is this something that I'll have to go to a garage/dealership for or will the likes of FastFit or Advance Pitstop be able to have a look at it?

I had been thinking that it was idling high when I'd start it up and occassionally the revs will bump up for a short time in idle as well. Aside from that it seems to be fine

It was serviced only 2-3 months ago, on that day they replace a "breather pipe" - I didn't know what that was though. Let me know if there's more information needed...

Thanks!
Nicola

Midnight_EG

Throw a bottle of petrol additive/cleaner in and send her back in.

vectra

Throw a bottle of Dipetane in half tank and give her a bit of welly.. Bring it back for a retest.. should be fine

Midnight_EG

vectra wrote: »

Throw a bottle of Dipetane in half tank and give her a bit of welly.. Bring it back for a retest.. should be fine

That's the name, couldn't think of it!


Or else use Red-Ex OP.

Lochaber

Thanks for the suggestion and I may give that a go alright but I'm still wondering why it might have failed in the first place? I did notice this morning when I checked the oil and the level seemed to be slightly over the mark - when I had looked in the past it would always be at the halfway mark... Could that can cause a problem at low idle only?

I've never heard of that Dipatene stuff though, do you need to use it for a while or do just throw it in before going to the NCT?

Midnight_EG

You pour it in before or after you fill your tank of petrol.

vectra

Lochaber wrote: »

I've never heard of that Dipatene stuff though, do you need to use it for a while or do just throw it in before going to the NCT?

Half fill your tank with petrol and pour a full bottle of Dipetane into it.. ( bottle around 10 Euro ) I know thee is a bigger one but that would probably be too much.
Then drive the car a bit harder than usual for 3 days before the retest.
That "should" clear it for you.
I havent heard of anyone this did not work for.
I used it in a civic there recently with 215,000 kilometers on the clock and it salied through on emissions.
I figure you may be doing a lot of stop start driving and also driving slowly??
You need to use the engine a bit to clear it.. "Drive her on"

Pkiernan

The fact that the car passed on high idle might mean that a fuel additive will not fix it.

I would also change the oil and filter if this has not been done recently. This can help with high HC levels.

However, I think you are looking at a hardware fix, such as an O2 sensor or a Mass Air Flow (MAF) sensor.

dr.fuzzenstein

Good service always a good idea, change oil and filter, new air filter and spark plugs.
Then put a bottle of additive in the tank and take it for a good, hard spin on the motorway, at least an hour each way, more if you can, why not go for a weekend in whatever county is furthest away from you.
Lots of pootling around going to the shops and back and only doing short trips builds up gunge in the engine and it needs a blow out.
If it still fails you will need a garage that can look at emissions and specialises in engine tuning.
Don't go to the likes of Advance for that, they're good for changing wipers and bulbs but I wouldn't let them do anything more than that.
Best ask a few people in your area for their own experiences with local garages.

hiluxman

fuel conditioner wont help. you should check for air leaks in the induction system

Lochaber

Thanks everyone!

I guess there's a chance that the additive won't help, not that I won't give it a go as well but I'd better ask part two of the question...

Can anyone recommend a garage who would particularly know about Audis or emissions in the South Dublin area? I'm out in Tallaght but I'll go anywhere around the county really - aside from the Audi main dealers, I've had far too many bad experiences with them.

Chazz Reinhold

Looking for a bit of help lads, mine failed over the weekend with the following readings

Low Idle: CO 1.57 vol% anything above 0.50% is a fail
HC 103ppm anything above 0ppm is a fail

High Idle: Lambda 0.88 between 0.97 and 1.03 is a fail
CO 4.41 vol% anything above 0.30% is a fail
HC 272ppm anything above 200ppm is a fail

Do you think the additive and a bit of holly should see me through?

Lochaber

Actually, a further question as well.

I had thought that the low idle HC had to be zero however I brought it to a garage today and they said that it just had to be under 200ppm.

Then I had a look at the NCT manual on their website and I didn't see anywhere where it mentions the HC on the low idle, it's only mentioned on the high idle.

Is that something that they just test it and list of the report but it doesn't actually matter?

AzureAuto

Clean out throttle housing and check vacuum hoses and have it reset using VAG com.
The car is running grand at a partially open throttle according to te figures, and these housings are notorious for getting gunked up with oily fume emulsions.
Seems to me the engine is struggling to breathe at idle, hence the incomplete combustion, (high carbon monoxide and unburnt fuel figures)

vectra

vectra wrote: »

Half fill your tank with petrol and pour a full bottle of Dipetane into it.. ( bottle around 10 Euro ) I know thee is a bigger one but that would probably be too much.
Then drive the car a bit harder than usual for 3 days before the retest.
That "should" clear it for you.
I havent heard of anyone this did not work for.
I used it in a civic there recently with 215,000 kilometers on the clock and it salied through on emissions.
I figure you may be doing a lot of stop start driving and also driving slowly??
You need to use the engine a bit to clear it.. "Drive her on"

I do know one person this didnt work for the car was scrapped, suspected it was burning oil! Was a 15+ yr old petrol suzuki cultus not worth overhauling. I put that dipethane stuff in my diesel vectra once and the fuel economy went up around 6mpg depending on how i drove it

vincenzolorenzo

Chazz Reinhold wrote: »

Looking for a bit of help lads, mine failed over the weekend with the following readings

Low Idle: CO 1.57 vol% anything above 0.50% is a fail
HC 103ppm anything above 0ppm is a fail

High Idle: Lambda 0.88 between 0.97 and 1.03 is a fail
CO 4.41 vol% anything above 0.30% is a fail
HC 272ppm anything above 200ppm is a fail

Do you think the additive and a bit of holly should see me through?

At high idle your engine is running very rich so there's a problem somewhere with the ECU or fuel injection somewhere along the way.

My own car failed on emissions last week as well.
Low idle was ok

High idle, Lambda = 1.02, CO = 0.53%. CO over 0.3% leads to a fail

It failed on emissions 2 years ago as well and I had to replace the cat (nasty price). Is there anything I can do to get the CO down or will i just have to take the hit on buying a new cat?

Lochaber

AzureAuto wrote: »

Clean out throttle housing and check vacuum hoses and have it reset using VAG com.
The car is running grand at a partially open throttle according to te figures, and these housings are notorious for getting gunked up with oily fume emulsions.
Seems to me the engine is struggling to breathe at idle, hence the incomplete combustion, (high carbon monoxide and unburnt fuel figures)

Thanks AzureAuto! I actually brought the car to a garage yesterday and they could find nothing wrong with the CO. Down to 0.1% at the low idle, don't know what's going on with it - they didn't do any more then since they couldn't see a problem and I needed the car back.

I did buy that Dipetane stuff though, I was going to put it in anyway as it seems to help fuel economy. If there is a problem would that clean out these housings mentioned as well or do I need to bring it to a garage for that?

Also it says 1:200 on it so I assume I stick to that rather than putting in the full litre on half a tank? (1/2 would be about 25-30 litres on my car I think) Or have people found it's best to put in more?