Catalytic Converter! Problem yet again! Starting to wind me up now :-(

[Lukeabercynonnoi]

Here's the problem I have this time guy's

After the car being run for about 3 - 5 mins, the catalytic converter goes cherry red hot!! Only noticed it when smoke started to come up from by the handbrake haa. Anyways, Took the cat off to check for a block, but it looks fine, and these you can also see the smoke coming from the back-box.

So now I have no clue as to what's up with it this time . . . A friend of mine seemed to think that not all the petrol in the engine is burning so it's heading down the downpipe into the cat and then carries on burning there. But if this is the case, any idea as to why the petrol is not burning like it should?

Also, I took the spark plugs out the other day and they had oil on them :S could this be the cause of the problem?

Many thanks

[Lukeabercynonnoi]

Does no-one know? lol

[Khare]

I would say it's overfuelling, as your friend said.

If the spark plugs were covered in oil I'd suggest changing them, they may not be burning the petrol well.

I'd also get a new temp sensor, always worth it as they tend to go off with age. It may be overfuelling because of that.

Plug the car into vagcom and see if the lambda is well, it may throw up a fault.

[AudiA8Quattro]

Are you losing lots of oil?
I would suggest maybe you are burning oil rather than excess fuel.

[Bellend]

Lambda sensors can cause this. As Khare said get it on a computer to see what the lambda's reading and check for any faults.

[boneybradley]

If it was/is burning extra fuel the cat will now be useless!!
proper vag-com should tell you about fuel issues (you will need live settings not just code scanning!)

[Craiglannon]

I think I have the same problem goin through loads of fuel and emissions are really high after running the car 5 6 mile and turning it off there's still smoke coming from the exhaust I have a slight oil leak aswell puttin it in the garage this weekend hopes it's not goin to cost to much

[tshirt2k]

A cherry red cat means heat. Unburnt fuel could cause this.  I think it could be running with a misfire or have ignition problem. fouled plugs, distributor cap cracked.

[Wayne]

I would suspect your dumping loads of fuel into the cat for it to get that hot.

[rubjonny]

try disconnecting the lambda probe plug, see if that helps. if it does you need a new one