98 VW Passat Emissions fail

Kencollins

Hi all,

A friend just had his car at the NCT, failed on a few bits including emissions.

The other fail items will come to about 200 euro (tyre, lights, track rod)

The emissions failure is really bad:

Low idle Co 2.55
Low idle HC 279

High Idle Lambda 0.87
High Idle CO 4.45
High Idle HC 3.18

The spark plugs look pretty worn, and the air filter very dirty. I know both of these could cause the car to run rich on their own.

My own feeling is that the cat is probably knackered. Would anyone else have any ideas? I dont want to fix anything on the car if the cat is gone because its burning oil and the 280 cost of replacement is more than the car is worth.

Would it be worth replacing the spark plugs, air filter, and checking the maf, and then seeing what the emissions are or would running rich for a long time ruin the cat anyway?

Thanks!
Ken

George Dalton

I have seen this multiple times before on these. The root cause is most likely the engine itself, specifically excessive oil consumption.

Kencollins

Hi,

Thanks for the reply!

I suspected the oil usage was something to do with it alright. There is no sign of an external leak, but the owner tells me that it uses over 1L of oil a week.

I think I will advise him not to waste his money and scrap the thing!

George Dalton

Most of the time they can be scraped through the test by a combination of fresh engine oil, throttle body clean and reset, fuel system cleaner, an "italian tune up" and a sympathetic NCT tester. But you are right it is probably not worth the hassle.