Another NCT emissions thread

eskerman

I had a retest on my 2006 Audi A3 1.6 petrol and it failed - I had a brand new CAT fitted last week and I also had the car tested at my local garage who has the equipment to test CO and it passed 100%

NCT re-test this morning failed on high idle 2820 with CO at 0.40 vol% - above 0.20% and I am struggling to understand what the problem is

No code faults - not showing any signs of oil burning - always serviced and it has 200km done -

The tester revved the crap out of the engine doing the test and handed me a failed/refusal on the high ideal test

Any idea where I can start to look especially as it passed emission test at my local garage

I always use good fuel and I have put Dipetane in the odd time as recommended by a mechanic

Feeling pretty pissed now

Thanks in advance

wotzgoingon

The reason the NCT test centre revs the crap out of it the car is to heat up the cat to drop the readings. I good few years back I got into a tiny bit of an argument over that. He said you failed emissions and I said sure why wouldn't I with you revving the crap out of the engine.


Regarding the readings these things are hard to sort as it could be a small thing best get a garage to look it over.

eskerman

wotzgoingon wrote: »

The reason the NCT test centre revs the crap out of it the car is to heat up the cat to drop the readings. I good few years back I got into a tiny bit of an argument over that. He said you failed emissions and I said sure why wouldn't I with you revving the crap out of the engine.


Regarding the readings these things are hard to sort as it could be a small thing best get a garage to look it over.

Thanks for your reply and opinion

I understand the car has to be running at "normal" temperature and revving the ****e out of an engine 'off-load" would appear to be counter productive at best...

The test garage to checked the emissions after a brand new CAT was fitted showed it passed CO with flying colours - it says the CO must meet 0.20% or less and I am getting 0.40% / the garage who tested for me didn't rev the ****e out of the engine and ran it at about 3000RPM which is the high idle speed the NCT does - well its 2800RPM

I am going back to the garage that tested it for me and see if they can re-test and replicate what happened at NCT

I hate wandering around in the FOG and at the mercy of test equipment or people who run the equipment - doctors differ and patients die springs to mind

biko

Moved out from someone else's thread

What were the other values, i.e. the lambda and HC at high idle?

rizzee

Bottle of redex/diptain and 20 quid petrol before the test!!

eskerman

samih wrote: »

What were the other values, i.e. the lambda and HC at high idle?

The lambda at high idle was 0.98 and it passed

The CO was 0.40 and it should be 02 or lower

HC WAS 103ppm and they passed

Seems to be running rich and boring fuel and consumption is high - going to get a full diagnostics done on the car as this is really turning into a money pit

The car has been very well maintained - always serviced using proper oils and filters .. its clearly something in the fuel trimming circuit

eskerman

rizzee wrote: »

Bottle of redex/diptain and 20 quid petrol before the test!!

I would prefer to find the problem to be honest - I think additives can be a tad misleading

With the lambda value of 0.98 the new cat would be the last component I'd be replacing. More likely a problem with air flow meter or lambda sensor or dirty injectors etc. When was the timing belt last changed? Maybe correct locking tools were used at the time and the timing is a bit off. Does the engine like a drop of oil? There are lots of possibilities why the fuelling maybe off and stop the cat doing it's job properly.

Take it to a good independent fuel injection workshop I'd say.

Edit. Not burning oil as you said in the first post but there are lots of other things to check. Cat always gets the blame as it's nice and expensive and straight forward component to replace without any analysis and a brand new cat can sometimes just about mask other issues at least for once NCT. The old OEM cats are also worth a lots of money when recycled so it's a win-win to sell you one that you don't need.