Catalytic Converter failure

[roger.grove]

I have a 2002 A4 3.0 Quattro. It is in the workshop due to running rvery rough and losing power. This happened after a 2 hour trip. They have replaced the coils, plugs and cleaned the injectors. Finally they have advised me that due to the coil breakdown the Catalytic Converters have failed and are causing the problem. Does this make sense? It has taken them a week to come up with this diagnosis so I am not confident.

[bez101]

I have a 2002 A4 3.0 Quattro. It is in the workshop due to running rvery rough and losing power. This happened after a 2 hour trip. They have replaced the coils, plugs and cleaned the injectors. Finally they have advised me that due to the coil breakdown the Catalytic Converters have failed and are causing the problem. Does this make sense? It has taken them a week to come up with this diagnosis so I am not confident.
id get it checked by someone else you seem to have had a few things done for them to come up with the cats

[Alan02]

If the coil packs had failed,you would get unburnt fuel into the Cat.which eventually would cause the Cat.to fail.I would ask them to run the car,if its possible to do now,and get them to do an Emissions Test to see what the Lambda/CO readings are.It may be that they are fine.On the other hand,the Cat.may have broken up and partially blocked the exhaust,so causing poor running/performance.Get them to clarify what the fault is with thw Cat.first.Cheers.

[tyreos]

I had similar problem last year and yes, it was the cat - Not cheap on 3.0 quattro I'm afraid - something in the region of £320 for the cat alone. My car had just done the exact same thing as last year and am pretty sure it's the cat again! Caused by a coil pack going down and only driving the cars about 8 miles home once the misfire started.

Sorry to jump on the thread but, does anyone know if the cat can be removed and the car run ok without it?? The car has a new MOT so won't need testing for another 11 months or so.

Any help will be appreciated and may help the original poster too!

Ta.

[roger.grove]

Thanks for the feedback.

Would a failed catalytic converter cause a misfire to continue? The coil packs have been replaced. However the tech said that 2 of them went "open circuit" when he put them in. I have no idea what he means.

Would you need to replace both cats if the misfires were all on one bank?

[bez101]

[QUOTE=tyreos;407340]I had similar problem last year and yes, it was the cat - Not cheap on 3.0 quattro I'm afraid - something in the region of £320 for the cat alone. My car had just done the exact same thing as last year and am pretty sure it's the cat again! Caused by a coil pack going down and only driving the cars about 8 miles home once the misfire started.

Sorry to jump on the thread but, does anyone know if the cat can be removed and the car run ok without it?? The car has a new MOT so won't need testing for another 11 months or so.

Any help will be appreciated and may help the original poster too!

Ta.[/QUOTE
has your car got 2 lamba on each cat ?
is so you can decat but have to have ecu programed so no lights
if 1 lamba on each cat u can just decat and no lights

[bez101]

Thanks for the feedback.

Would a failed catalytic converter cause a misfire to continue? The coil packs have been replaced. However the tech said that 2 of them went "open circuit" when he put them in. I have no idea what he means.

Would you need to replace both cats if the misfires were all on one bank?
i cnat see why a failed cat would make the car misfire and if on 1 bank only that side cat will go

[tyreos]

In response to this post, i've just picked my car up (3 litre a 4 quattro) from my local garage.

My random misfires on 4, 5, and 6 WERE caused by the collapsed cat.

Changed the nearside cat, actually welded in a stainless steel uni cat and modified it for the lambda sensor, and it's now perfect.

Analysis - coil pack no.4 failed - I drove car approx 8 miles with slight misfire, causing the cat to fail and hence the other problems.!!! In the meantime, I changed all the coil packs, plugs and Mass Air Meter! IT WAS JUST THE CAT!!!


DO NOT DRIVE A4's WITH A MISFIRE FOR HOWEVER SHORT A DISTANCE - I've been caught twice now and it's not cheap!

Happy motoring

:o

[TheProducer]

Would a failed cat cause an egg smell, or is that something else that is likely to cause the smell and ofcourse the cat failing?

any help please.

Bill

[Kiwi Kranker]

In response to this post, i've just picked my car up (3 litre a 4 quattro) from my local garage.

My random misfires on 4, 5, and 6 WERE caused by the collapsed cat.

Changed the nearside cat, actually welded in a stainless steel uni cat and modified it for the lambda sensor, and it's now perfect.

Analysis - coil pack no.4 failed - I drove car approx 8 miles with slight misfire, causing the cat to fail and hence the other problems.!!! In the meantime, I changed all the coil packs, plugs and Mass Air Meter! IT WAS JUST THE CAT!!!


DO NOT DRIVE A4's WITH A MISFIRE FOR HOWEVER SHORT A DISTANCE - I've been caught twice now and it's not cheap!

Happy motoring

:o

Ouch! I drove mine for (I kid you not) 67miles with a failed coil pack and a misfire and my CATs survived and its just passed an emissions test.

Dead set miracle, I was all geared up for new ones. Mind you I nursed the car along at about 1800RPM at which I either couldnt feel the misfire or the coils managed to cope with.

Think Ill keep some money aside in case the CATS fail!:D

[Crazy L]

Hi all

Reading this post with interest. I drive a simple '01 (Y) A3 1.8, It started to misfire at high revs a while ago, then the zorst started to rattle. The misfire now resides through the whole rev range.

Took it to a garage during the week, the rattling was because my cat had fallen apart, and the engine light was one because of a "misfire", I wasn't told much more than that tbh. Didn't think nothing of it, checked HT leads for resistance, and put a new coil pack in today, still the same.

Then, I read this thread. So they could be related? I have no code reading equipment and know noone to have a look "for a drink" but I obviously need a new cat, so there's a chance if a new one could cure my misfire problems?

Would the problem murder a new coil pack though, dont fancy buying another. ta muchly.