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

[Mandrake]

Simon,

Have you actually tried changing the fuel filter?

Nope, not yet.

Since diagnosing lean on wide throttle I've put one on order though.

Our V6 was once running a little sluggish and it turned out that the old fuel filter might of been blocked as the new filter made the car run massively better.

David.

Thats encouraging to hear. It would certainly be embarrassing if after all this the major power loss turned out to be a blocked fuel filter...trouble is I've had so many different and constantly varying symptoms that its been hard to pin down and separate them all. I have identified and fixed other problems along the way like definitely faulty spark plug leads, replaced a missing inlet manifold gasket, (both of which made a big improvement to a misfire) and (hopefully) fixed the gearbox problem with the oil. The symptoms have changed over that period of time but still the engine doesn't run well if anything its worse recently despite fixing some of the problems.

So here's hoping that a fuel delivery problem is the last remaining problem...and won't be too hard to find or expensive to fix... (Please don't be the fuel pump... )

[lexi]

Have you actually tried changing the fuel filter?

Pah! Don't be silly David ! Simon would have to do a test first on 5 filters by hacksawing through them. This would reveal if any illegally imported fibres like banana pulp or hemp were present. Before this though The Spectrum Analyzer would be used to check the accoustic properties of each canister for ringing . Flow rates and glues would be checked. Only then after exhaustive tests could such a move be undertaken

Joking mate!!

[Mandrake]

Haha very funny. In truth I don't know why I haven't changed something simple like the fuel filter yet...

The symptoms have constantly changed in the last few months though as well as being intermittent, I think the thing that got me confused is that everything went wrong soon after that 800 mile trip in July and I'd been looking for one fault that fits all the symptoms not considering that multiple things had gone wrong at once from the stress of the trip...and sorting through the intermingled symptoms of multiple faults has been tough.

I also don't have any experience diagnosing fuel injection problems... aside from this one, the only two cars I've owned with fuel injection are my previous 2 litre Xantia, whose engine never had a single problem in 4 years, and a Honda Accord (don't laugh ) which also never gave a moments trouble with the engine over 5 years. Neither ever had any poor running symptoms to diagnose, they just worked. (You can tell how old the rest of my cars have been then if they have all been carbs )

I'll have a fuel pressure gauge very shortly so I'll be able to diagnose these type of problems much quicker and more accurately in the future. (assuming it does prove to be the problem) Live and learn.

[addo]

You'll be shocked at how much sundry tees, hose clamps and bits of SAE 30R9 hose cost you.

[Mandrake]

You'll be shocked at how much sundry tees, hose clamps and bits of SAE 30R9 hose cost you.

I know, its unbelievable, many of the kits are well up into the hundreds of pounds, with a dozen adapters you'll never use unless you work at a garage...

I was originally thinking of getting just a gauge (which you can find for around the £15 mark) and a 1/8 NPT to schrader valve adapter pipe but then found out there's at least 3 different types of schrader valves used on different brands of car, (Citroen seems to use 8mm metric) and that I couldn't actually find an adapter by itself for sale anyway...

I also released that to do the job properly and safely I needed a dump valve to bleed the pressure safely to an enclosed bottle - even though the schrader valve is self sealing I don't want any squirts of petrol into the engine bay, and for some of the tests you need to quickly bleed the pressure and re-pressurize again.

After much searching I eventually found this for £32 which was basically the cheapest kit I could find that included a dump valve and the correct schrader valve adapter:

http://www.ebay.co.uk/itm/400359808842? ... 1439.l2649" onclick="window.open(this.href);return false;

Only about twice the price of a gauge by itself with no fittings or pipes so not too eye watering - I'm just writing it off as an investment to continue building up my kit of car tools and diagnostic equipment. Maybe I fit a new fuel filter blind and it fixes the problem, maybe it doesn't and its something else like the pump or regulator which are too expensive to replace without thorough diagnosis. At least with this I'll be able to know for sure what the problem is or isn't, and next time I need it I'll already have it. I'm getting a bit tired of replacing parts that are suspected to be faulty but turn out not to be. In the long run having better diagnostic equipment is going to save me money and a lot of aggravation.

[addo]

Tools? Buy this - it's round the corner from Our Jim - he'll be happy to mind it until you collect.

http://www.ebay.co.uk/itm/170971969467" onclick="window.open(this.href);return false;

[Mandrake]

Tools? Buy this - it's round the corner from Our Jim - he'll be happy to mind it until you collect.

http://www.ebay.co.uk/itm/170971969467" onclick="window.open(this.href);return false;

[CitroJim]

Tools? Buy this - it's round the corner from Our Jim - he'll be happy to mind it until you collect.

http://www.ebay.co.uk/itm/170971969467" onclick="window.open(this.href);return false;

Sadly it's no longer available...

[Mandrake]

Tools? Buy this - it's round the corner from Our Jim - he'll be happy to mind it until you collect.

http://www.ebay.co.uk/itm/170971969467" onclick="window.open(this.href);return false;

Sadly it's no longer available...

It says 0 bids, so the auction ended without it selling. You could always contact the seller if you really wanted it.

[Mandrake]

ITS FIXED!!!!!!!!!

It's going like an absolute rocket ship now, I still can't wipe the grin off my face after all this time trying to find the problem. I'd forgotten just how grunty the V6 is, and I think its going even better than it ever has since I've owned it.

It was great to meet up with David Hallworth today (despite the abysmal weather conditions, just above zero degrees, wet, overcast with light snowing) and have a drive of one of his Xantia's to compare to mine, however I spoiled David's fun by actually stumbling across and fixing the problem with the engine yesterday, so the trip to David's turned into more of a test drive and social visit than a visit for troubleshooting help.

Before I reveal what the fault was I thought it would be fun for the contributors to this thread to place bets on what the problem actually was, given that so many possibilities have been explored - fuel system, ignition, low compressions, blocked exhausts, sensors and so on...

You get one point if you guess the correct subsystem of the engine (eg fuelling, ignition, exhaust, sensor inputs and so on) and two points if you identify the actual component that was faulty within the subsystem.

Since David knows what the fault was he is disqualified from answering. (shhh!) Go to it.

[oneday]

fuelling, ignition, exhaust, sensor inputs and so on

[Mandrake]

fuelling, ignition, exhaust, sensor inputs and so on

Bzzt. Sorry, you have to choose only one.

[oneday]

no idea but its good to hear you got it sorted you deserve it after all your efforts

[CitroJim]

My brain today is just not up to guessing games but Simon, that's absolutely excellent news and I'm looking forward to hearing what the duff bit was

[DHallworth]

I'll not give the game away or say anything to hint but I will say that it is certainly driving like a fixed car!

I took Simon for a run in mine and then let him have a drive of it. I then took his for a drive and the power/performance of both cars was identical. The gear changes on Simon's were smooth as silk apart from when it had a hiccup going from 2nd down to 1st. It rode beautifully as well.

Interesting to note that the steering on my V6 was heavier then it was on Simon's V6. I've never thought mine was heavy but it was fairly noticeable that Simon's was a little lighter.

Looking forward to meeting again in the summer on a good day so I can bring the XM out of the garage without it getting wet

David.