C5 removing dpf - can cat be removed?

[Peachy5860]

Hi all,

I've removed the necessary dpf bits from the ecu and I'm in the process of removing the physical filter from the car. My question is, is it possible to replace the dpf/cat with a straight through pipe so I can de-cat as well? I'm a bit confused about what would happen with the various sensor and things that are currently connected to the dpf/cat?

Thanks in advance.

[cachaciero]

Well if you have removed the FAP bits from the ECU then it shouldn't be looking at the dif pressure sensor at all but you could leave it connected electrically just not connect the pipes, which you wouldn't be able to do on a straight pipe as the unions wouldn't be there. When I get around to doing mine I was planning on retaining the existing pipe just remove the internals, which I believe would allow allow some exhaust noise reduction as compared to a straight pipe.

cachaciero

[Peachy5860]

Thanks for the reply. I figured as much but wasn't sure as there are about 4 or 5 wires/pipes attached to it all. Are they all for the dpf and can be discarded/left unconnected?

There are 2 pipes connected to the cat which are proving to be absolute buggers to undo, if they are not needed anymore I might just cut them and tuck away

Cheers

[Lighty]

Problem is if you remove the DPF canister the car will fail the mot due to the modification, if you leave the canister intact, at least they wont be able to tell visibly, so if the car is running well you should still get under the limit.

[citronut]

if it has two labada sensors one each end of the cat it might not be easy to de/cat your car, as the sensors tell the ECU what is going in and out of the cat,

also the two pipes i belive are what read the FAP presure,

regards malcolm

[Peachy5860]

Thanks for all the replies... I hadn't thought about it failing the MOT because it's visibly different.

I've got the filter out (what a nightmare that was!) and I've beaten the crap out of its internal and it's now just an empty cylinder what do people normally do with the cat, is it possible to do the same I.e. knock out its internal and leave an empty shell... is it even worth doing?

Your opinions welcome...

[Monkeyfeet]

I've recently done just this. I reprogged the ecu not to see the fap and knocked out both the filter and the cat whilst it was all apart, seemed kind of silly not to really. Same as you, I found one of the pressure sensor pipes would not undo at all. (even with two of us using 4ft bar and 3ft stillsons...). But as Lighty and Cachaciero say, with everything piped up and connected it still looks standard. These engines are pretty good in that it won't be chucking out any smoke anyway.

[nick]

Problem is if you remove the DPF canister the car will fail the mot due to the modification, if you leave the canister intact, at least they wont be able to tell visibly, so if the car is running well you should still get under the limit.

Not under the current rules. There's still no visible check for cats or DPFs on diesels in the MOT, only cats on petrols.

[cachaciero]

Thanks for all the replies... I hadn't thought about it failing the MOT because it's visibly different.

I've got the filter out (what a nightmare that was!) and I've beaten the crap out of its internal and it's now just an empty cylinder what do people normally do with the cat, is it possible to do the same I.e. knock out its internal and leave an empty shell... is it even worth doing?

Your opinions welcome...

I did read somewhere that the best way was to drill down the length of the filter with a suitable size masonery drill 3/4 of inch comes to mind, author reckoned that 5 holes down the length of the filter was more than enough as regards the cat if there is no MOT check for unburnt hydro-carbons I guess that could go as well, still can't believe that in this day and age they don't use some kind of gas analyser.

cachaciero

[Peachy5860]

Thanks monkeyfeet, that's the reply I was hoping for out of interest have you noticed any difference in power since doing it?

[Lighty]

Problem is if you remove the DPF canister the car will fail the mot due to the modification, if you leave the canister intact, at least they wont be able to tell visibly, so if the car is running well you should still get under the limit.

Not under the current rules. There's still no visible check for cats or DPFs on diesels in the MOT, only cats on petrols.

No but its coming very soon.

[Peachy5860]

I did read somewhere that the best way was to drill down the length of the filter with a suitable size masonery drill 3/4 of inch comes to mind, author reckoned that 5 holes down the length of the filter was more than enough as regards the cat if there is no MOT check for unburnt hydro-carbons I guess that could go as well, still can't believe that in this day and age they don't use some kind of gas analyser.

cachaciero

I didn't have any masonery bits to hand so I started with a hammer and chisel (which took forever) and ended up using a drill bit used to drill holes through wood - don't know the technical term for it but it worked a treat!

On to the cat next and then the fun of puttin it all back on the car!

[nick]

Problem is if you remove the DPF canister the car will fail the mot due to the modification, if you leave the canister intact, at least they wont be able to tell visibly, so if the car is running well you should still get under the limit.

Not under the current rules. There's still no visible check for cats or DPFs on diesels in the MOT, only cats on petrols.

No but its coming very soon.

There have been endless rumours of this for about the past 18 months but it isn't now going to happen for the forseeable future, if at all. The visual check for cats on petrol engines came into force on 1 Jan 2012 (along with numerous other changes to the MOT) but it was finally decided not to introduce a check for cats on diesels as had previously been threatened.