Xantia V6 broken exhaust (update: and rough low rpm running)

[Mandrake]

So anyone have any thoughts on my slow oxygen sensor video ? Has anyone else tested the response time of their oxygen sensor before or am I navigating uncharted waters ?

[Mandrake]

The other giveaway with a sticky or collapsed lifter is its noise! Dak-dak-dak-dak.... This can on some motors, be confused with a variator - but the Xantia's V6 doesn't have VVT. The compression pressure jumping similarly on all pots says to me that (as expected) there is no valvetrain issue.

An interesting and useful find for you is Autometer accessory 3224. Unlike most such kits offered, it doesn't use solder but brass or copper compression olives to seal the tubing - making it ideal for exhaust pressure checks.

Now that I'm ready to test the exhaust back pressure and order a replacement oxygen sensor I've dug this post back up. I see a few of these listed on ebay, all from the US, this one seems to have the lowest postage cost: (some are absurdly high)

http://www.ebay.co.uk/itm/Auto-Meter-32 ... 3ccf9420dd" onclick="window.open(this.href);return false;

Does this look like it would do the job ? What I'm not sure about is whether the fittings are the correct size and thread to screw into the oxygen sensor port on the cat pipe ? Are you able to confirm that addo ?

Getting a connection to my gauge at the other end shouldn't present a problem, I'm sure I can adapt something as the other end of a 6 foot long copper tube won't be hot, certainly not for the short length of time it needs to run to get a pressure reading...

Regarding the oxygen sensor what do people think about this one ?

http://www.ebay.co.uk/itm/181042864366? ... 1438.l2649" onclick="window.open(this.href);return false;

It's £66, but I'm looking for an OEM type. I know there are cheaper "universal" ones, but I've had a bad run in cheaper pattern parts lately including a DOA MAP sensor, so for the amount of hassle to get another DOA part or one that doesn't work properly or last very long I'd rather just get the genuine part if this is indeed the correct OEM one...(I'm a bit mystified that it says 1998-2003, given Xantia's were only made until 2001 )

[Ben82]

I'm a bit mystified that it says 1998-2003, given Xantia's were only made until 2001

Could be confusion caused by fleabay... it seems they list the S2 years as going up until 2003.

[CitroJim]

You can get plugless oxygen sensors a lot cheaper Simon. I'm sure you’re up to crimping up some butts to re-use yourr old plug...

I've used these quite happily...

[addo]

For the gauge connection I used a zinc plated 1/8 NPT female to AN adaptor and sawed off all but 2mm of the AN side. Then I drilled a corresponding hole in the nearside of the cat in-pipe so it was a neat fit. The local exhaust place welded it in for $20. When not in use it has a brass 1/8 NPT plug screwed tight into it.

[Mandrake]

Jim: crimping the wires is not a problem, I'm just concerned about the quality and compatibility of generic types after the reading I've been doing, and my general bad luck on cheap pattern parts where I spend more time sending them back and paying return shipping to do so than I do actually fitting the part to the car...case in point being the MAP sensor where a 5 minute job turned into emails to the seller, trips to the post office, paying shipping etc just to return what was basically a piece of junk. At least with a MAP sensor its easy to take it off again, not quite as easy with the oxygen sensor.

Then it happened again with the injector tester I bought - the cheapest I could reasonably find, simply didn't work properly, (only supplying the injectors 5 volts instead of 12 ) seemingly due to a design flaw rather than a fault, (it had ground side switching, but a 7805 supplying the positive output!) I debated sending it back but felt sure the replacement would have the same issue after at least a week mucking around getting it replaced so I opened it up and modified it slightly to get the job done... I've been chasing the engine problems on this car for so long now that I think if I were to fit a DOA or poorly functioning oxygen sensor that would then need sending back I would probably crack up.

Addo: The gauge I would use is my combined vacuum/pressure gauge which reads up to about 8psi pressure, it just has a ribbed plastic fitting designed for a push on rubber hose.

Does anyone know the thread diameter and pitch of the oxygen sensor ? I suppose once I get the new one I'll have one on hand to find this out. I really don't want to drill any extra holes in the exhaust for this, I'm quite happy to use the oxygen sensor port while the oxygen sensor is out. Once I know what the back pressure is (with and without the silencers downstream of the cat connected) and the problem is diagnosed I won't be needing it again...

[addo]

Oxygen sensor is a right mongrel to get to; I find the easiest way is to disconnect the back box and let the centre/cat hang down. After changing it you'll appreciate what I mean - routing the lead through all its cabling ties post-construction is an absolute mission. You have to unplug it first and release from most of these clips or it will wind up the wires as you screw out the sensor.

Sensor thread is like an old Ford spark plug - M18×1,5mm. Once you've eyeballed it, you'll appreciate why I went the alternative route (and how little this impacts on performance).

[CitroJim]

It's quite a fight in a V6 too Adam...

Not impossible though..

[Mandrake]

I've seen where the oxygen sensor is and it doesn't look too bad really for access, from underneath up on ramps - about on a par with doing the handbrake cables, which was a real pain but partly because it was the first time I've done them...

With my pressure test I'm hoping to identify (a) is the exhaust restricted, and (b) if it is, is it a broken/melted cat or is it further down stream...(which I hope to determine by re-testing the back pressure with the cat to center silencer connection disconnected, even though it will p**s the neighbors off no end during the test )

On the off chance that the cat is ok and there is a blockage behind it in one of the silencers, what are peoples thoughts on this exhaust kit ?

http://www.ebay.co.uk/itm/261114285243? ... 1438.l2649" onclick="window.open(this.href);return false;

I've had it on my watch list for quite a while now. Any good, or likely to be cheap and nasty ? I think I could pretty much fit it myself, (or maybe with a wee bit of help ) and save a ton on paying someone else to do it. Of course if I'm keeping the cat I'll have to cut 4 slots in the pipe from the silencer to use a standard clamp - as that's the modification me and Richard had to do to work around the broken cat tail sleeve... (still sealing tight and working perfectly by the way ) but that's no big deal especially when I can do it before fitting to the car...

Of course if the cat is blocked that changes the situation, I'll cross that bridge if I get to it...

[xantia_v6]

The ebay vendor has sold 2 of those, including 1 to me, and it is the best fitting V6 exhaust I have had, including genuine systems. The sound is fairly good, a little noisier than genuine, but much better than the other systems I have bought on ebay. The only issue with fitting was that the inner diameter of the sleeve going onto the cat tail was a bit tight, and I had to grind it out slightly with a dremel. I was happy paying £95, now the price is reduced to £65, it is a steal, and I suspect that there won't be any more after these have gone.

[Mandrake]

Small world! That's actually really good to know, even with £12 shipping it sounds like its a bargain then. Hearing that its a goodun' actually makes me a bit nervous about keeping a close eye on the listing to make sure I don't miss out, although I'm sure I've had it on my watch list for a couple of months now, hopefully it won't disappear this month as I probably couldn't get it until next month.

The existing exhaust is quite noisy and boomy, much boomier and noisier than the V6 I drove belonging to David Hallworth, it sounds like all the baffles are blown out of the mufflers... and they're very rusty as well. (Interestingly the degree of boomyness to the exhaust note varies from day to day just like the performance of the engine... ) In short whether or not there is a flow restriction there they're at the end of their useful life and I've just been putting off replacing them due to cost...

[xantia_v6]

The amazing thing is that £12 postage gets it from Poland to the UK in 3 days.

[CitroJim]

Right, that does it. I'm ordering one for stock right now...

[CitroJim]

Just in case anyone else wants one and can't find it, you can find it here...

It's bizarre you can get a complete system for a Xantia V6 for £77 all in but for an XM V6 with the same engine they simply don't exist

[Hell Razor5543]

How different are the exhausts between the Xantia and XM V6? I wonder if they are similar enough to adapt one to fit the XM?