Faulty Cat

[Ric]

Hi everyone,

Firstly, hello, just registed on the forum.

I have a 1999 V Gti 2.0 8v, which has a knackered cat, as a result the car feels like its got a missfire when coming off throttle, the engine hunts around at idle, and I'm sick of the sight of petrol stations 

I'm not concerned about increasing bhp, but have been advised to fit a CRP as the cheapest option.  However, I am worried about the lambda sensor.  I don't know where its located on the exhaust system, so will it still error without a cat on?

Any advice will be much appreciated.

Cheers, Ric

[rtking449]

Hello mate i have the same model of golf and have had similar probs

There are 2 lambda sensors one in front of the cat one behind.Who has told you it is the cat converter thats wrong, sounds more like air flow meter or one or both of the probes.The march issue of the Golf mag has an explanation for consistent faults like this,they say it is common on this model
Cheers Richie

[richandhazel]

With those symptoms I too would be suprised if it was the cat at fault. In my experience, when they fail, they usually make a lot of noise because the honeycomb section has broken down, or they fail the emissions I once had one where part of the honeycomb section actually broke away and tilted 45 degrees to the gas flow. Car still ran ok but it made a hell of a racket!

[Ric]

Thanks for the update chaps.  It does make a racket, sounds like the heat sheild vibrating agianst the cat, but you can only hear that when the car is started up, and under low acceleration.  I think a trip to the diagnostics at VW is in order.

Cheers, Ric

[richandhazel]

I agree. I think there is something else that is causing the poor running and high fuel consumption. Unless the cat is actually blocked, which is unlikely. I assume the exhaust gasses are flowing through to and out of the tail pipe freely?

[Ric]

It certainly looks / feels like the gases are getting out ok.  Under brisk acceleration the car feel ok, it does run of steam sooner that it should be doing, and I won't run with the climate on, drains the power that little bit too much.  A strange one, will keep investigating and report back.

Cheers, Ric