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

[Stempy]

With regard to the rear bank of plugs fouling more than the front, if you look at the design of the inlet manifold and engine breather return, you will find that all the oil mist from the engine gets recirculated to the rear bank only. I would guess that this is because rear banks tend to run warmer that front banks, or just that it was the most convenient position for the breather return. Not likely to be a problem except on vehicles only used for short journeys that don't get hot enough to burn it away.

[Ben82]

Simon, on the 4000rpm thing:

Although the ES9J4 engine is reasonably smooth and very reliable, driving the engine reveals that there is a power output spike at around 4000 rpm that Peugeot did not feel was in keeping with the smooth cruiser image of the car and it quickly became apparent that for an engine of this capacity fitted in a car like the 406 Coupe, the ES9J4 was not putting out sufficient power to meet market expectations

[lexi]

Are these type of additives useful for helping to clean out sticking hydraulic tappets, or are they just snake oil ?

Worth a go. It is either that or do 2 oil changes in a month I think. No idea about sticky stat. Uncle Jim did one but I don't remember the symptoms.
I dare say the stat won't be a tenner?
Howd'ya explain to a woman that Dyno's ain't just for playing on?

[Mandrake]

With regard to the rear bank of plugs fouling more than the front, if you look at the design of the inlet manifold and engine breather return, you will find that all the oil mist from the engine gets recirculated to the rear bank only. I would guess that this is because rear banks tend to run warmer that front banks, or just that it was the most convenient position for the breather return. Not likely to be a problem except on vehicles only used for short journeys that don't get hot enough to burn it away.

You're talking about the pipe on the left hand side below the main throttle plate which has a squeeze connector with an o-ring ? When I was refitting that yesterday I was looking at it and wondering what would be the consequence of that o-ring leaking - given that it's on the vacuum side of the throttle plate... and from what you say it feeds more predominately into one bank than the other...any leak there would surely upset the mixture.

Also if that is the crank case breather, what is the pipe that connects at 8 o-clock to the main flexible air line from the throttle plate to the air filter box ? It also has a bit of oily residue in it and the same type of squeeze fit clip and o-ring... and until very recently the squeeze fit connector was a poor fit onto the small hose it attaches to due to being pulled off there every time the air filter box comes off...so I now have a hose clamp on that small pipe keeping it attached to the clip...

[Mandrake]

Simon, on the 4000rpm thing:

Although the ES9J4 engine is reasonably smooth and very reliable, driving the engine reveals that there is a power output spike at around 4000 rpm that Peugeot did not feel was in keeping with the smooth cruiser image of the car and it quickly became apparent that for an engine of this capacity fitted in a car like the 406 Coupe, the ES9J4 was not putting out sufficient power to meet market expectations

Hi Ben,

Yes I've come across that exact quote before on my internet travels, I'm not sure I agree with it though. Also what I'm noticing is not a peak in power output occurring at 4000rpm and falling off progressively on either side, its a step in the power output - low power below 4000rpm, normal power above 4000rpm with an abrupt step transition.

The worse the car is running in the mid band the more obvious the step is, and as far as I can see apart from when the plugs were fouled the performance above 4000rpm is ALWAYS ok. If I'm in sport mode at 4000rpm in any gear and I put my foot down it FLIES, instant power, no lag, even if moments earlier it was acting a bit lethargic at 3000rpm. I noticed this characteristic months ago when the engine was running really poorly, it was almost un-drivable at low rpm but suddenly at 4000rpm it would fly.

If you'd take off in 1st gear in sport mode it would be a bit sluggish at first, hit 4000rpm and suddenly go like a scalded cat as if you'd suddenly snapped the throttle wide open. That's why I'm wondering if the knock sensor signal could be holding back the timing at lower rpm but not above 4000... The Lexia would answer that question but without a co-driver its too dangerous/difficult to watch it, and I can't graph the data..

(This car would be SO much easier to diagnose if I could only log and graph the engine data like you can on yours! )

[Mandrake]

Are these type of additives useful for helping to clean out sticking hydraulic tappets, or are they just snake oil ?

Worth a go. It is either that or do 2 oil changes in a month I think.

I wonder if it would be best to put the additive in with the old oil, leave it a few hundred miles then do a change for new oil, or would it be better to put new oil plus additive in straight away and leave the additive in ? I'm leaning towards the latter - get the old oil out as soon as possible.

No idea about sticky stat. Uncle Jim did one but I don't remember the symptoms.
I dare say the stat won't be a tenner?

Yeah a thermostat won't be expensive, but it looks like I'll have to drain at least half the coolant due to where its located. And if I'm doing that its the obvious time to replace the split coolant expansion tank that really needs doing and change the coolant as well, which all adds up...(£40ish for the expansion tank ?)

If the top hose test shows signs of the thermostat sticking open I'll definitely replace it though, I'd be crazy not to.

[RichardW]

Citroen only want £22 for the stat surprisingly. Carparts4less want £16, so I'd go with genuine in this case. Aftermarket stat I ftted to my HDi only lasted about 15k miles before it started to go baggy - must change it out again!

[Ben82]

(This car would be SO much easier to diagnose if I could only log and graph the engine data like you can on yours! )

Just a thought, if you have (or know someone with) an Android phone, it might be worth getting one of those cheapo £15 bluetooth OBDII dongles, and get Torque pro? (~$5)

Since it seems like you have the data available to you (hopefully over OBDII too), just not the graphing ability, which if the data is available, the app should fill that gap

[addo]

He's an iPhone user.

Howd'ya explain to a woman that Dyno's ain't just for playing on?

Easy, it's better value than womens' footwear, a day spa or astrology sessions. How about that gym membership where they pay for three months and go for less than three full weeks? And if you happen to raise this valid point (or mention the extra pair of sneakers bought through the gym at "members' prices" although they didn't really need more sneakers), somehow it's your fault...

[Mandrake]

(This car would be SO much easier to diagnose if I could only log and graph the engine data like you can on yours! )

Just a thought, if you have (or know someone with) an Android phone, it might be worth getting one of those cheapo £15 bluetooth OBDII dongles, and get Torque pro? (~$5)

Since it seems like you have the data available to you (hopefully over OBDII too), just not the graphing ability, which if the data is available, the app should fill that gap

As addo mentioned I have an iPhone and don't know anyone with an Android phone (that would lend it to me anyway ) but the real problem is that the Xantia is not OBD-II compatible despite the 16 pin OBD-II connector - to the best of my knowledge no generic OBD-II reader can talk to a Xantia... only a Lexia/ELIT/Proxia.

[Mandrake]

Citroen only want £22 for the stat surprisingly. Carparts4less want £16, so I'd go with genuine in this case. Aftermarket stat I ftted to my HDi only lasted about 15k miles before it started to go baggy - must change it out again!

Sometimes a few quid shaved off here and there backfires doesn't it ? What do you mean by baggy ? Do you mean it warms up slowly because it won't fully close, or does it not fully open so get a bit too hot after heavy driving ? Or a bit of both ?

[Ben82]

(This car would be SO much easier to diagnose if I could only log and graph the engine data like you can on yours! )

Just a thought, if you have (or know someone with) an Android phone, it might be worth getting one of those cheapo £15 bluetooth OBDII dongles, and get Torque pro? (~$5)

Since it seems like you have the data available to you (hopefully over OBDII too), just not the graphing ability, which if the data is available, the app should fill that gap

As addo mentioned I have an iPhone and don't know anyone with an Android phone (that would lend it to me anyway ) but the real problem is that the Xantia is not OBD-II compatible despite the 16 pin OBD-II connector - to the best of my knowledge no generic OBD-II reader can talk to a Xantia... only a Lexia/ELIT/Proxia.

Point is a little moot without an Android phone, but seems at least someone has had some success on a Xantia

[Mandrake]

I have to say I'm dubious Ben I've looked pretty hard for information on 3rd party readers for talking to the Xantia and found nothing... The HDi engine ECU is very different to the ES9J4 ECU... maybe it is possible to read an HDi but not the ES9J4.

[RichardW]

We've got a 'driod phone. I've also got cover for driving other cars on my insurance if you need a pilot

Stat in mine doesn't close properly (at all?) running temp has dropped to 70-75, where it should be at 90. The original one lasted 100k, but the replacement less than 10k before it started to go off. My experience of Citroens is that the stats tend to fail open after 90 - 100k. Oh, look, what is yours at ???

Interesting that the fault appears to clear at 4k rpm - if only you could interrogate the ECU to find out what it ignores at that engine speed...although knock sensor does sound favourite!

[Ben82]

My t'stat failed after about 75k (stuck open, which made the computer think for some reason it was overheating!), both the ES9J4 and ES9J4S have the same ones.

Seems like you have a good offer there SImon from Richard, it's just whether it's worth the ~£20 punt to see if it works (although you could potentially sell the device on afterwards to lessen the cost too).