Xantia TD 1.9 Removal of Catalyst - Observations

[ecohouse1]

My down pipe with the cat was on its last legs. Rust claimed it at the forward join to the catalyst. I was suprised how quickly it went downhill. Slight blow on saturday then almost complete shear by the following saturday. Anyway wanted to fit a straight through pipe. £32 online inc delivery and turned out to be a Bosal pipe (was stamped all over it)

Initally worried as a full 2" shorter than the pipe on the car! But fitted perfecting as the back box was being pushed too far back with the old pipe.

Bolts on the turbo/ manifold were a pain to reach. One of them is at a dodgy angle to get a long socket and extension bars on, so needed the ratchet spanner on 1/4 turns - a real ball ache! Fitted it in the torrential rain last saturday in East Scotland - what a joy! New pipe went on easily enough and I always tap & die the old bolt & nut so that goes on with finger tips.Old Wire Ring stuck hard on the Turbo flange - had to hack it off. Had a fitting kit but wire ring too big and bolts shorter than the ones on the car. Wondered if iot was HDi kit? Had a "never used" wire ring from the BX which fitted a treat!

With the new pipe on - definitely notice more power especially lower end torque.

Slightly more noise but I suppose the Cat also acted as a silencer to some extent.

More of a diesel fumey smell at tickover - eg warm up in the drive in the morning than I remember before. Reminds me of the old 1.9 D 309 I had in the 90s.

WIll be interesting to see if the mpg lifts up over 42/43 that I get in mixed driving at the moment.

Cheers

Alan

[spider]

Without the cat the exhaust will be more fragant , although depending on the age of your car will determine its 'tune' a bit as they progressively set new timing settings for new models, I think 95/96 and again 97 they wound them down a little bit more for the XUD. I'd have to check but I think it was originally 11 degrees then 10 then 9.5.

I guess it can act as a semi silencer although I do worry about coke in diesel cats, 1.4 HDi springs to mind here can coke right up on these in some cases.

Might see a tiny increase in MPG as its not restricted although the increased torque may be all you initially notice.

I'd give serious thought to unplugging the EGR (just the vacuum pipe and block it properly) if its still connected as that may help MPG a fraction. It won't give more power unless there's a problem with it but a small increase in MPG may be possible as fresh air is better than partially re-using exhaust fumes I think.

Regarding the 'ring seal' they can be a pain sometimes can prise off with a large blunt pry bar or screwdriver though.

Talking of annoying to reach I always really struggled with the downpipe on the new shape 306 NA XUD unit as these had EGR and the outlet in the manifold was really offset to one side to make it very difficult indeed to do. It was slightly easier (I found) to initially try to get it from above.

[ecohouse1]

Thanks Spider. Which pipe on the EGR do I unplug? Its hard to see the damn thing on the Xantia - access from above is impossible and i was peering up to the turbo on saturday, I could just make it out at the top. Will it get through an MOT with it unplugged or is it a case of making the alteration "discreet"!

[spider]

It will have no effect on your MOT emissions output they only measure smoke opacity really. If it was worse then you have something amiss.

I'd suggest leaving the electrical connectors alone (can store a silent fault on some models, K light should not come on anyway but fault will be stored probably "Permanent fault EGR electrovalve is open circuit" or something like that) and just removing the vacuum pipe that operates it.

Plug the end, the vac pump side 'feed' to the valve at least, don't leave it open so its 'sucking' as you don't want an open vacuum circuit. You may be able to take the small pipe off the t-piece and blank that (see last sentence) or suchlike.

No vacuum = EGR diaphram cannot move when electro-valve opens to provide (now awol) vacuum to said valve. Default position is closed and sprung shut. Vacuum used to open it. No vacuum = no opening = good.

The end injector 'leak off' caps make ideal small bore vacuum line plugs I find. I use them for this purpose.

EDIT.. Changed 'servo' for 'vac pump' as I forgot its a Xantia with its hydro-fangled braking system.