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

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addo
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Post by addo »

I hope the net balance of everything you sought when moving to the UK, remains in the black. I keep looking at this thread, and being reminded of why I love Australia.

lexi
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by lexi »

Firstly Simon.......great news on job front. It will cushion your expense on cars :-D

Just do your best on the car and see how it goes. I wouldn't chase the gearbox thing. It is fair do's for us to be playing around and taking chances with cars as playthings

Not worth it. You will spend £600 plus chasing that box and these cars are worth nowt.

You are in a different situation with trying to get your feet on ladder here. Get something sensible for a bit if the V6 goes belly up. Save for a bit and stabilise..........then you may get another toy. You have to be sensible with the little lady

Fingers crossed the box may have some life in it. Somebodys on here went at 79k.........instantly!. My Vel has the same type of creature in it although Aisin/Warner type. Like a DMF or Turbo ......it is in the hands of the Gods I suppose.

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Thanks Alex, still waiting to find out the starting date for the new job, should know next week. Can't wait to get out of the **** that I'm working in now. =D>

Getting the gearbox overhauled is out of the question for me at the moment. It's not even physically possible unless I had a garage of my own to do the work on the car in and a hoist to get the engine/gearbox out, let alone the cost, so I'll nurse it along carefully with minimum driving for the moment.

One piece of possibly good news though regarding the poor and intermittent running of the engine - the last few days the weather has been VERY wet and damp with a lot of moisture hanging in the air and the engine has been absolutely diabolical. I'd say overall power has been down to about 40% of what it should be, and its been almost un-drivable below 2000 rpm. It's been shuddering badly when trying to pull, (feels like knackered engine mounts) missing, lots of groaning from the gearbox etc, really quite unusable, I've been having to manually hold the gear lower or use sport mode to keep the revs up and have some sort of driveability.

Today the weather has suddenly shifted and the moisture and humidity have plummeted to the point where you can feel the dry air on your lips and surprise surprise, the engine is running vastly better. Overall power has gone up to about 80% of normal I'd say (eg twice as good as yesterday) there is little or no missing, no shuddering at low RPM and its almost pulling normally below 2000 rpm. The gearbox (?) still lets out a slight groan if I put plenty of power on at 1500rpm but its very minimal compared to yesterday, unless I push it hard at low revs (around 3/4 throttle at 1500rpm) it didn't groan at all.

To me this dramatic turnaround of engine performance with humidity/moisture screams out ignition problems, and spark plug leads in particular. I already know I have two faulty spark plug leads, does this just prove it even more ?

Is there anything else that might be wrong and worth checking that would cause the engine to run so badly in high humidity and run quite well in low humidity or have I well and truly nailed the blame on the spark plug leads ?

It would explain a lot of the inconsistency I've noticed - for example when I visited Richard the car would hardly play up, as it happens that day was a very cold crisp day with blue skys and very dry air...likewise days where the car has been really awful have always been wet miserable days with loads of moisture hanging in the air...(no shortage of those here... :roll: :lol: )

The fact that the groaning from the gearbox (??) was very minimal tonight unless I used a lot throttle at low revs does make me wonder if the lumpy torque from a misfiring engine (or the data supplied from engine to gearbox ECU in such circumstances) really does upset the gearbox a lot...

The very first chance I get I'm going to put these new spark plug leads in. I don't care if its cold or overcast, if its not raining they're going in. :wink:

lexi
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by lexi »

I am thinking that the glow worms will be showing under the engine cover on a dark night should you look.

The shorting can usually be seen.

Son and D.I.L. now back from NZ. Good news is that she landed a big job with bank and
they will head out in Feb to settle there in your old region :-D

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CitroJim
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by CitroJim »

Hope the weather is on your side to do the job today Simon and hope too it cracks it [-o<

Certainly there's an interesting correlation between weather and performance there. Engines do seem to run a little better in cold dry conditions due to greater oxygen density but the difference should not be that marked!

Looking forward to hearing good news :wink:

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Thanks Jim.

As it happens the weather gods smiled on me today, it took about 2 hours to change the spark plug leads, 30 minutes tidying up and going for a test drive, and then literally as I was carrying stuff back up to the house it started raining. Couldn't have timed it more perfectly. =D>

The inlet manifold was a fairly easy job the 2nd time, I didn't refer to any instructions I just got stuck in, the main snag was transferring over the spark plug lead guide to the new spark plug leads - figuring out exactly how far along the cables to attach it was awkward, there is NO spare length in the leads at all, at first I couldn't get lead 3 (left front) to reach the connector so I had to peel it back out of the guide and pull through all the spare length but I got there in the end.

While I had the plug leads out I checked the spark plugs and found that they were very loose - they all came undone with almost no effort at all, I'd obviously (as I suspected) been a bit of a nancy tightening them up the first time for fear of striping a thread, the crush washer on the plug wasn't even biting at all, so I checked all the plugs and refitted them tightening them up good and tight this time until they bit down a bit. (hopefully not too tight this time, there was no sign of the threads stretching and easing off) So it's possible that they may not have been sealing 100% since I had changed them.

I've only been for one 20 minute drive so its early days but there does seem to be a big improvement in the running of the engine, it seems a lot more grunty right through the rev range, doesn't seem to labour nearly as much at low revs now, is much smoother, also seems quieter - both the exhaust which is a lot less boomy and the engine noise overall. Doesn't seem to need much throttle now to get about. Idling is a lot more steady although still not perfectly steady when hot. All in all a big improvement, assuming that todays test drive wasn't just a fluke. It must have been misfiring quite badly.

Things it hasn't fixed - the groan is still there around 1500rpm under load, when cold it barely does it but after driving enough to warm everything up it gets more pronounced, I still saw a couple of examples of shuddering when pulling away at low revs when the car was hot, (lockup clutch shuddering maybe ?) and the gearbox is still sometimes schizophrenic in its behaviour.

During the first part of my test drive I was giving it a bit of stick on a 60mph country road and it was performing perfectly - no apparent slipping of the lockup clutch, very zippy performance, normal smooth gear changes etc...then in the latter part I was doing 25 - 40mph and the gearbox didn't know what it wanted to do, it was erratically changing its mind about whether it wanted to shift up or shift down etc, never sure what it wanted to do.

I think the next step is to clean the connectors on the cable from the ECU to the gearbox, I have a feeling that a lot of the "can't decide what to do" behaviour (which has been there to some degree right since I've had the car) could be due to dodgy speed sensor data coming back from the gearbox to the ECU. Way back when I first read the fault codes on the gearbox it did indeed have temporary speed sensor fault codes logged for both speed sensors, and although it hasn't logged any since then I am still suspicious of the quality of the road and torque converter speed signals from the gearbox.

If those speed signals are a bit erratic but not bad enough to log a fault it's going to confuse the hell out of the ECU and mess up both the gear changing algorithm and the regulation of the controlled slip mode which relies on precise torque converter input and output speed readings to regulate...it could also confuse the auto adaptive calibration since it calibrates itself by measuring the slip in response to the timing of the clutch actuations, and could explain why an auto adaptive reset gives a temporary but not permanent improvement.

Where is the access to the kostal connector ? Is it through the top after the air filter box is removed, or is it through the left wheel arch ? I can't say that I noticed where it was today, although I didn't have time to look carefully for it.

I still have another oil change to do as well, the stuff that came out was pretty mucky, I think if anything is going to solve the groaning noise (aside from a rebuild) it will be flushing out all that dirty oil...

lexi
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by lexi »

The best description for doing up spark plugs is to give them a "Tight Nip"lol:
Good job you checked that........loose plugs can overheat cylinders.

There are instances when auto boxes can't make their mind up though. They all do it to a certain extent. Yours could have a fault ......maybe..

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DHallworth
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by DHallworth »

I must of been on the forum without my glasses on recently as I'd totally missed this thread!

If you want a Xantia V6 to compare it to for performance, drivability and gearbox groan then feel free to give me a shout!

I collected a 1999 T reg Xantia V6 the other day and am more then happy for you to compare them both. I've also got a Lexia to make comparisons if you wish. If you want to pop over drop me a PM.

Regards

David.

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CitroJim
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by CitroJim »

Well, that's good news Simon :)

The gearbox Kostal connector is obscured to an extent by the extension on the battery tray that supports the intake hose to the airbox. Pop that off (three 10mm screws) and it'll be more obvious...

On the subject of speed sensor signals and things, I'd be temped to get someone trustworthy to drive the car and you sit in the passenger seat and watch live data on the Lexia. That might well show something up and give a clue as to why the 'box seems very undecided...

Good job you found those loose plugs too. It can also do in the threads in the cylinder heads...

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

DHallworth wrote:I must of been on the forum without my glasses on recently as I'd totally missed this thread!

If you want a Xantia V6 to compare it to for performance, drivability and gearbox groan then feel free to give me a shout!

I collected a 1999 T reg Xantia V6 the other day and am more then happy for you to compare them both. I've also got a Lexia to make comparisons if you wish. If you want to pop over drop me a PM.

Regards

David.
Hi David,

Thanks for the offer, I think I'll take you up on that (a good excuse to meet another FCF regular :) ) although I'm not sure whether it could be soon or have to wait for the new year, as well as Christmas coming up I'm in the middle of changing jobs at the moment so things are a bit up in the air and I don't know what weekends I'll have off until my notice is handed in as my old job is shifts and the new job isn't...

Are you saying yours sometimes makes a groan noise under load at low RPM ? It would be great to drive another one and also have you drive mine to see what you think of the symptoms - I think Jims idea of monitoring the live data from the gearbox on the Lexia during a test drive is a great idea - I could try monitoring the Lexia while you drive for example. :)

I too have a Lexia, so no problem there. :) I was going to PM you a couple of months ago for a Lexia session when I was first trying to diagnose the poor running of the engine but ended up deciding to get one myself. Even though it didn't reveal any engine fault codes to help with that diagnosis I'm still glad I got it as it has been invaluable, particularly the live sensor data.

The engine is running a lot better since I did the plug leads so I think that's been the major engine fault - two intermittently broken leads to the rear plugs and no doubt the insulation has broken down as well causing loss of spark to the surroundings when damp.

I still have a second gearbox oil change to try (I was going to do it today but weather didn't allow) as well as cleaning the contacts on the ECU harness, we'll see if that makes the gearbox any happier. If its still not happy after that I'll sort out a time to come visit you. (or maybe even if its working fine :) ) Where abouts are you ?

Hard to believe you didn't spot this thread, its turned into something of a mega-thread, if you do read through it you've got a bit of catching up to do! It's now badly named as it started off with an exhaust problem (now fixed, so ignore that) then went into poor engine running and finally gearbox woes...I should really just rename it a day in the life of Simon's V6 :lol:

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Hmm, after a lot of short trips today to the dump and elsewhere the car seems to be back to some of its old tricks once warmed up. When hot the gearbox is eager to hold too high a high gear in my opinion - when slowing down and rounding roundabouts it is quite happy to hold a high gear with full torque converter lock up as low as 1200 rpm and won't change down or release the converter lock up even with as much as half throttle - leaving the engine to struggle to pick up and pull away. (Along with a bit of staggering and groaning)

I also notice that when hot the low RPM performance is rather flat - when cold relatively little throttle pulls away eagerly, you just have to touch the throttle and it zips away. When hot at slow speeds <25mph after slowing down it takes a lot of throttle to do bugger all and it wont kick down until at least 3/4 throttle despite being below 1500rpm which just seems wrong to me. Whether its because the engine is down on power when hot, or because the gearshift/lockup strategy is different and is holding the revs down by using too high a gear is still unclear... :?

I know that when cold the gearbox favours higher SK programs and once it is warmed up and driven casually it will fall back to SK1 - the lack of urgency and pickup does seem to occur in SK1. I also know that the torque converter lockup strategy is designed to change with temperature - when cold its more eager to let the torque converter slip to help warm the gearbox oil up, likewise when the oil is getting too hot it will deliberately limit the use of full slip mode to prevent the torque converter overheating, thus applying full lock up a lot more readily. There is no doubt from the driving behaviour that full lockup is engaged far more often when hot even at low RPM and road speeds. A combination of excessive use of full lockup and SK1 seems to make the car really struggle at low speeds.

I have to say, I'm absolutely baffled by this car, I really thought I had it with the spark plugs but it was right back to its old tricks today... :( I can't understand why its behaviour changes so dramatically between hot and cold.

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DickieG
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by DickieG »

Reading your description above I can't help thinking that the box normally behaves like that especially if you drive on a light throttle, as its auto adaptive it defaults to economy mode and requires a sustained period of spirited driving to wake it up. Having woken up one of these boxes in that manner it then takes another 5 or so minutes for it calm down, if by pressing the sport button the box behaves more as you would expect it to you have found the answer.

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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Yes clearly its adapting its program to driving conditions, (and temperature) but why is economy mode (SK1) so gutless and undrivable ? I can't believe a 3 litre V6 should struggle so much with simple around town driving through junctions and roundabouts. It really is gutless when it falls into this behaviour pattern, no question about it. I'm having to manually change down a gear (or use sport) to stop it struggling and have decent pickup so I can get across a roundabout safely.

It's fine if I accelerate from stationary and don't progress too sedately, (in which case it would change up too soon) but if I slow down for a roundabout then enter it without stopping causing it to stay in 2nd or 3rd its hopeless. :( In slow moving stop start traffic it really is a chore to drive at the moment, my 2 litre auto was a delight in the same conditions...

addo
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Post by addo »

I'm reminded of my car's recent struggling with a badly blocked cat.

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Mandrake
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Post by Mandrake »

addo wrote:I'm reminded of my car's recent struggling with a badly blocked cat.
I can't help thinking that the cat may have been damaged when the exhaust broke and the cat fell down on the crossmember. Is there anything inside it that would be brittle that might have been damaged by a sudden jolt like that ?

The car passed the emissions test with flying colours at the MOT in August, and I don't recall any lack of power problems at that time, two weeks later the exhaust broke, and despite the joint being fixed and clamped up the engine has never run the same since...coincidence ? Maybe not. :?