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

[KP]

Oh I most certainly did!! Simon is going to post something up I believe about it and I'm happy to let him post it up as it's a very nice surprise

[Mandrake]

Yes after all my fretting and worrying it did indeed pass.

There were advisories for pretty much everything I expected:



In my opinion the lower arm bushes are completely shot (the rubber has completely pulled away from the centre shaft so that you could insert a pencil between them with the suspension on high!) but who am I to argue with the MOT man. Of course a different garage may not have been so forgiving so it might have been a fail elsewhere - luck of the draw with so many things marginal.

The big surprise though was the absolutely spotless emissions report! I was almost certain this would be a fail and it was my biggest concern of all. I don't have a copy of last years report any more as I gave it to Will, but suffice to say it was a near fail, from memory it was HC 40, fast CO 0.27% and idle CO 0.49% - which would have failed this year as I see both the CO limits have been reduced compared to last year.

Well here's what it got:



HC was actually a fraction lower than the new V6 (3 vs 4!) although the CO was significantly higher than the new one, but still very good for an old car with such a chequered history!

If you look for advice on the internet about the high CO and HC readings it got last time the almost universal advice is that the cat is poisoned and will have to be replaced, and that was the opinion of some on the forum too.

I clung tenaciously to the belief (wishful thinking, perhaps) that the cat was not faulty and that the misfire and engine running problems it had at the time of the test were the cause of the high emissions reading, well either I was right all along or the cat made a miraculous recovery!

I don't know exactly what it was but in hindsight I think it was probably either the wrong O2 sensor (with the low heater wattage) being fitted and/or the second hand coil pack which was causing an ignition misfire at the time of the test. It now has a new correct OEM O2 sensor and a good fairly new coil pack - no more misfire and now the emissions are vanishingly low. So at least some of the work I've done to the engine over the last year has cured it's emissions woes and given it a clean bill of health in that department.

Another possibility is that some types of cat poisoning such as carbon build-up on the catalyst material can be reversed if you run the cat hot enough for long enough for the deposits to be burnt, thus restoring effective running. And Will has certainly given it a good blast since buying it...

Edit: I just remembered that I had the injectors professionally cleaned and balance tested as well - perhaps the better injector balance also contributed to vanishingly low emissions, especially HC, as 3 ppm is way better than even its first MOT where it got 20ppm.

It's a bit strange how the black carboned up exhaust is at odds with the emissions pass, but maybe the engine conditions that were causing the exhaust to carbon up no longer exist.

So there you have it, it was interesting to at least get some closure on the emissions front...so anyone struggling with emissions on a V6 don't give up on the cat too easily - those OEM factory fit cats are tough as old boots! That one suffered months of running with a misfire (which will melt down many smaller cats) and still came out ok in the end when the engine issues were fixed.

Oh and by the way, it still has the 3.5 bar fuel pressure regulator in it (instead of a standard 3.0 bars) so this is pretty good proof that running a higher fuel pressure (which gives a bit better wide open throttle performance, and somewhat compensates for this engines running problems, where it was trying to run lean at WOT) is not harmful to emissions test results as long as you have a good O2 sensor!

One final thought - despite it passing the MOT I don't regret selling it and buying the one I have now. Despite the pass there are a lot of near fails looming for next year and work to be done, not to mention a gearbox on borrowed time.

I'm really loving the new one, apart from the hard spheres that need replacing as soon as possible it drives and sounds like a new car - it looks really nice despite a couple of scratches, goes like a rocket, the gearbox is smooth and quiet, it's a pleasure to drive really, and it has very very little wrong with it and apart from a small exhaust leak nothing looming that needs doing for next year apart from normal maintenance and consumables.

[KP]

Cheers Simon

The car still occasionally misfires below 3k revs and the engine wasn't totally warmed thru at the test but as I'm back there Saturday I'm going to ask for another one to be done after a really good blast

I have been running the car hot and that was one reason I out standard unleaded in for the long run home. The higher speeds and engine loads get it just that bit hotter and it's had one 20litre odd shot of Momentum this week and some good blasting around the roads and some in neutral to give the exhaust a good push.

The pads and exhaust are going to be an easy fix, oil leak is probably a rocker, and bushes... I may well leave that to the next owner really.
Front brake pipe I'll likely clean up and treat with some anti rust primer and then bitumen spray over to keep it long lived.

The rest of the story will come in the next week or two as things develop. The worst part im still undecided what way to go with the bonnet, if there was another MK2 locally with the same colours and good nick I'd likely have it and fit it but chances are zilch!

[KP]

And the radio is driving me nuts so I need to look at that as well think the changer will need a strip down to fix the ERR6 that it throws up and I'm hoping the aerial cable is just lose on the back of the head unit as otherwise I have to pull the headlining back to get at the aerial base and cable

Checked and the suppressor is there and plugged in but not sure if I can test it works any other way

[Mandrake]

Are you sure it misfires below 3k ? Or do you mean its just down on power ? If its just low on power then I reckon its the timing getting retarded.... Try taking the battery off for 10 minutes to reset the ECU and see if the zip below 3000 comes back - bet it will, for a few days anyway. Why ? I don't know...

The rear cam box is leaking both at the top and bottom seal - not a major enough leak to drown the spark plugs but still a significant leak, and it drips onto the rear exhaust slightly. I assumed that the oil leak advisory is for the hydraulic leak though - from the power steering pressure regulator or nearby pipe I think, but hard to be sure as the wind blows it everywhere in that area, even up onto the cruise control vacuum pump!

Shame about the bonnet, I nearly fitted Richards old one which only has a couple of small stone chips by the grill and is a perfect colour match, but its a long way from you unless it somehow made its way down on the forum courier network!

The radio has something wrong with the reception - its weak unless you're in a strong signal area and usually sounds distorted, I assumed it was a fault in the radio. I usually just played my phone via a cassette adaptor. The CD changer worked fine for me but I didn't use it a lot and only used original CD's not CD-R's. Never saw an ERR6.

Have you tried a cleaning CD ?

[CitroJim]

Simon, I think the MOT pass is all down to your devoted care over the past couple of years

Most V6s run rusty exhausts but I've seen another fly the emissions test with a sooty one too...

[RichardW]

Apparently I can weld to MOT std then....

Surprised there is no advisory for both rear tyres having screws in them, and being down near the limit....

[KP]

The tester was happy they were within the limits and is happy some work is being done on it, I did say I wanted anything that could be an advisory to be made one but he doesn't nit pick too much on advisories

[Mandrake]

Apparently I can weld to MOT std then....

Yep. I had no doubt that welding would pass.

Surprised there is no advisory for both rear tyres having screws in them, and being down near the limit....

I don't remember the rear tyres being down near the tread limit ? Or was it the front tyres you're thinking of ?

[KP]

I'll check later but I think there is still meat on them for me if they are over the markers and not cracked I tend not to worry unless they are shocking in the wet which is critical for this country!

Richard how much for your bonnet? And where are you?

[RichardW]

Free to a good home.... I'm in Lanark, only about 15miles down the road from Simon

[KP]

PM sent

[Mandrake]

The problem is transporting it - they're not exactly small or light! That's a job for a panel van as I'm assuming courier costs for something that large and unwieldy would be excessive...

[KP]

using some famous words....
'I have a cunning plan!'

though im hoping it will fit sideways into the back of an XM or xantia, im sure its been done before by someone on here like Paul or Jim...

[CitroJim]

Good excuse for a visit, do the swap there and then and drive home again

Anyway, soon I'm sure we'll need a visa and passport to visit Scotland and spend hours at Hadrian's Wall Border Crossing so take adavantage of an easy vist whilst you still can!