emissions failure on audi 1.8 this morning

v240gltse

hi,

my daughters 1999 Audi A3 1.8 failed the nct this morning for emissions failure which in fairness are very high ( see attached)

I ran Vag-com over a month ago and got a

fault 16518 oxygen ( lambda sensor ) B1 S1 no activity
P0134 - 35 - 00 - -

I cleared this error and yesterday reran Vag-com without any errors showing up so I'am wondering where to start

if i have to change the lambda sensor where is it and how easy to change ?

thanks in advance

brendan

crosshair1

Why is the low idle so high??
Fix that first and see how it behaves.

v240gltse

hi crosshair1

yes indeed that is odd as the car idles at about 850 and we had taken it for an Italian tune up before heading into the center.

regards

brendan

muckeyw

Me thinks and I've seen this befour check your car for vacuum pipe leaks (il describe if you wish) just ask and or remove your egr valve and clean it fully and refit I've seen this problem afew times in our garage

v240gltse

hi muckeyw

is the egr valve only for diesel cars or petrol as well ??

thanks in advance

brendan

muckeyw

Nope petrol do to

v240gltse

hi,

left the car into a local indie and when he rang back he's found 2 items were faulty

1. the oxygen sensor was faulty ( fair enough )

and here's the part that galls me

at some stage the previous owner/owners had the insides of the catalytic convertor removed completely and the car now requires a new sensor and cat to get through the NCT :mad::mad: .

I trust this garage so i don't think they are making it up and sure I can always ask to see the old one

is there any way to check if a car has had this sort of work carried out to it ????

thanks in advance

brendan

v240gltse

hi

Well the saga continues the cat, lambda sensor has been replaced and while reduced emission figures occurred they are still WAY over the limits. :eek:

all sensors have been checked and are within spec and NOT throwing up any codes but the mechanic says that the cause appears to be over-fueling issue and is at a bit of a loss of where to go with this. :(:(

We now reckon that the reason it had the cat contents removed was initially due to this over fueling problem which burnt out the cat and they simply emptied it rather than fixing it :mad:

The plan is to get the ecu checked but even at that its fingers in the air time. I would really really appreciate any help in order to get this working before my daughter gets back from holidays and i lose my mind.

thanks in advance

brendan

crosshair1

What mechanical tests have been carried out?
What vacuum do you have, both on scan tool and gauge?
Something must be out of place in live data.

Ecu testing...dont waste your money.

isainmdom

As crosshair said what has been checked . Somethings to check would be MAF if its failing it doesnt always throw a fault code, check for any vacuum leaks and hoses around turbo,check pcv, check coil packs,check throttle body, if vag is communicating with the ecu then its unlikely to be at fault

v240gltse

hi crosshair1

He has checked all the vac pipes and can find no leaks at all. As i can only reply with what the mechanic is telling me can you help by telling me what exactly to ask him regarding readings and expectations of those readings ?

As he said he can find no devices giving a fault code but in comparison to the old days of carbs and chokes its the equivalent of having the choke on full time.

sorry i cant be of more help giving you the information you need

regards

brendan

crosshair1

He should have a vacuum gauge reading of 20" approx, this will correspond with map sensor reading about 320mbar from live data.
Ideally a smoke pressure test of the intake system to identify any leaks.
You should also confirm that the temperature readings in data are ok, and that there is activity of the oxygen sensor and if its switching.
I'm pretty sure that these also require an adaption of channel 00 after fitting parts to reset learned values.

Tea drinker

check the coolant temperature sensor, it's a very common failure on these that can cause over fuelling. Not 100 sure but I think it can fail with seeming normal dashboard readings. There's also an air intake temp sensor, not sure what that is under vagcom.

Is it a 1.8t? Is there a higher pressure fuel pressure regulator fitted in an effort to get more fuel in? Bigger injectors? Just worried about how far it's been dicked with - potentially.

v240gltse

hi and thanks for the help.

i believe this sensor has been checked but will double check anyways. No its a standard 1.8 se spec and to be honest at this stage i would love to meet the previous owner trust me :mad:

thanks again brendan

Tea drinker wrote: »

check the coolant temperature sensor, it's a very common failure on these that can cause over fuelling. Not 100 sure but I think it can fail with seeming normal dashboard readings. There's also an air intake temp sensor, not sure what that is under vagcom.

Is it a 1.8t? Is there a higher pressure fuel pressure regulator fitted in an effort to get more fuel in? Bigger injectors? Just worried about how far it's been dicked with - potentially.

muckeyw

Hi me again iv seen all the comments and I would agree id actually spend 25 euro and change the coolent temp sensor il nearly put my life that's the fault.just out of curiosity what mechanic you using as I've said I live near u

v240gltse

hi all

well here's the update and boy did it cost :(:(:(:(

1. new cat ( and a very hefty discount )

2. new lambda sensor

3. new maf

4. wiring fault found in behind dash

5. temp sensor on engine

6. coolant replacement

7 and of course labour.

what came first the chicken or the egg i dont know but best guess is that the cat started to rattle and the owner rather than replacing it just got it emptied and this in turn eventually caused the lambda to fail and somewhere in this mess the maf decided to act up.

The car is running great and the readings of the emissions the garage gave me are extremely low ( thanks god ) and I have the car booked in for the 29-Sept so fingers crossed.

Love to find a cheap tool for checking the emissions myself while examining a car before bloody buying it.

ah well that's the joys of motoring these new fangled, computer driven, emission compliant machines

regards

brendan

Tea drinker

Thanks for the update Brendan, that must have been painful! At least is should be runnig like new now with alll those new sensors in, should save a bit on juice too.

v240gltse

hi tea drinker

it bloody better run on just petrol vapors for the next 2 years ;)

regards

brendan

v240gltse

hi all

it passed with flying colours last night at the NCT. :D:D:D

regards

brendan