Cat

[wizzer59]

Could do with some advise, I am in the process of removing the filter material in my cars dpf and need to know if there is any advantage in removing the cat as well before I put it all back together??????????????

[myglaren]

I imagine that if the DPF is clogged then the cat will be too.
Removal could very well improve performance but you will need a cat come MOT time.

[wizzer59]

realy! I thought through reading on here that it didn't make to much difference on a diesel

[wizzer59]

actualy I don't think the dpf was that clogged even though the fault code said so

[myglaren]

realy! I thought through reading on here that it didn't make to much difference on a diesel

It doesn't - the main difference is detrimental but it is required for MOT purposes.

[wizzer59]

How will the MOT man Know if its in or not?? Thanks for answering by the way

[myglaren]

Sorry, I presumed you were intended upon complete removal, if just the innards are removed they will be unlikely to tell, unless of course it fails the emissions test - highly unlikely.

[wizzer59]

Ah sorry bout that, yes just innards knocked out, I've put it all back together now so will leave it in for the time being, is it something that gets blocked or needs replacing much? the car has done about 110,000 miles.

[myglaren]

Depends on the type of driving, Short trips with a long time to go cold in between will bung it up fairly quickly. They need a good long run at reasonably frequent intervals and they will burn off the crap when they get good and hot.
Under those conditions they will sometimes start an automatic regeneration process, you may see all the electrical equipment come on and notice a marked increase in fuel consumption, along with a significant amount of smoke. If so just keep on until the process is complete.
Around 100 miles on a clear motorway late at night is often a good time to do it.
Ideally it wants to be doing 4,000 revs, so fourth gear and hustle along.

[wizzer59]

Blimy so it sort of does the same as the dpf, I think mine should be ok as most of my journeys are wales to w, sussex and back again

[myglaren]

That was mostly in reference to the DPF but the cat gets clogged up too.
Reasonable use should keep it clear, it's town driving that fouls it up.

[SaabC5]

Ideally it wants to be doing 4,000 revs, so fourth gear and hustle along.

Hustle along? At 4000rpm in 4th my 2.2 will be doing 100mph+

Third gear at about 60mph is a bit more legal if you know what i mean.

[Monkeyfeet]

Once you've got the thing off the car, then successfully undone it's four bolts, by the time you've smashed out the dpf with a big fat hammer and a rod - I'll bet that you won't be able to resist smacking out the cat as well.........
(well while you're there....)

[wizzer59]

Thanks guys, If it makes no real difference to economy or performance then I think Ill leave it be

[Duke137]