Simon's new Xantia V6 and Leaf blog

Tell us your ongoing tales and experiences with your French car here. Post pictures of your car here as well.

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Hi Jim,

The irony is it was me who broke the tabs on the original sensor (I think) because I swapped the air box and concertina hoses across from the old silver V6 before it went, as there was a small tear in the large concertina hose from the air box to the throttle plate, and the screws in the air box were all rusted too. Yeah, I'm picky, but when the old car was supposed to be getting scrapped for parts, (not resold on ebay *cough*) naturally I'm going to swap any easily swappable stuff that is in better condition :lol: I wasn't sure about keeping the air temp sensor from the silver car (whose tabs were also broken) in the air box but in the process of swapping the sensors between the two air boxes I broke the tab on this one too! #-o

Now that I've fitted this new one I can see why - the hole that they go into is keyed with 4 small slots so that you push the sensor into the hole when it's on about a 45 degree diagonal with the tabs lining up with the slots, then turn it 45 degrees to lock it into place - the strange thing is I've only ever seen them sitting at this 45 degree angle on both V6's I've had, and when you turn it around straight (in line with the filter housing) to lock in place it then pulls the cable fairly tight, almost as if it was not designed to be turned to that position, yet if I left it at the 45 degree position that I inserted it at (and which the original was sitting) it was trying to fall out on its own... :?:

I would certainly check the air temp sensor on your V6 conversion and replace it if there is any doubt - OE parts are available on amazon (of all places) for about £6.25 so it's a bit of a no brainer.

I'm not surprised that reading too high could affect performance - remember on the Silver V6 at one point when I thought it was running too lean I connected that variable resistor in series with the air temp sensor to fool the ECU into thinking it was colder than it really was, thus making the mixture richer - reducing the apparent temperature reading by about 10-15 degrees was enough to make the mixture about 10% richer.

Before replacing this sensor I have occasionally seen on the Lexia air temp sensor readings in sunny (~20 degree) weather as high as 40-45 degrees after the engine bay has 30-60 minutes of heat soak from hard driving, and whilst the intake air will be warmed quite a bit by the hot air box that always seemed unusually high to me - if the real reading should have been say 35 degrees instead of 45 degrees in those conditions then that could easily cause the mixture to be significantly too lean, and a lean mixture on a hot hard worked engine will make it more prone to knocking and needing the timing cutting back by the ECU...

I haven't checked the air temp reading after a hard drive since, but as the weather is getting colder now I probably wouldn't be able to reproduce those conditions until next summer anyway.

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CitroJim
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Re: Simon's new Xantia V6 blog

Post by CitroJim »

I'm sure all of my spares have broken tabs Simon so I'll take the opportunity of getting one (or two) in stock from Amazon.. Thanks for that tip :-D

I never used to try to remove them when taking the airbox off. I used to disconnect them and leave them in place...

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

This is the one I ordered:

http://www.amazon.co.uk/dp/B0085CUQOK/r ... g=UTF8&me=" onclick="window.open(this.href);return false;

Note: the £6.94 direct from amazon not £9.46 from "Ace Parts" - not sure why you can't link directly to amazon as the seller...

I never remove it when taking the air box off either Jim - but I was swapping the air boxes between the two cars (last year) and wanted to keep the same sensor as the other one had broken tabs, but they both ended up broken when I was finished with them. :-D

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CitroJim
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Re: Simon's new Xantia V6 blog

Post by CitroJim »

Simon, that's lovely. Thank you!

Yes, I believe it's almost impossible to remove a sensor without breaking tabs...

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Went for a lovely trip yesterday from Glasgow up through Loch Lomond and around the top, back down through Sterling and back home again - about 3 hours of driving albeit only 150 miles or so, thanks to plenty of windy country roads and lower gears...

This is the first long trip the car has been on in quite a while, regular readers will know that sadly this car like the previous one does get used largely for "milk runs" that are not befitting a V6 and doesn't regularly get a chance to stretch its legs for any length of time. It ran very nicely yesterday, in keeping with the improvements that I noticed since I changed the air temperature sensor.

Today I've been for a number of runs to the rubbish dump (a bit further than a milk run, but still shortish :lol: ) and oh my god, this thing is going like a bat out of hell! :twisted: It feels like a caged animal that is pulling at the leash and just rearing to go. It is honestly that zippy and punchy today that I'm amazed. I thought it was going quite well yesterday, today it is incredible. =D>

Clearly the long journey yesterday did it some good, it's too much of a co-incidence for it not to be that but the curious part of me wants to know why ? Anyone have any ideas why a good blast yesterday has made such a difference ?

The obvious answer is the spark plugs may have had a bit of carbon fouling on the insulators, but they're quite new plugs, good quality OEM spec Bosch plugs of the correct heat range so they shouldn't have fouled even with a lot of short trips.... should they ?

Another thing that has changed recently is it has had an oil change and filter a few weeks ago and yesterday was the first really good run it's had since that job was done. Could the detergent action of the new oil have had a chance to work now and clean out some gunge from somewhere - hydraulic tappets maybe ?

Or could it be something like a bit of carbon build up in the combustion chambers getting burnt off ? (Do "modern" cars still suffer this affliction or is that a thing of the ancient past ?)

Any other possibilities ? I would say it's performance today is quite possibly the best its ever been since I've had the car.

I'm really curious to know what changed because it sure is fun to drive now when accidentally pressing the loud pedal a bit much on takeoff results in a mad scrabble of wheel spin.... :mrgreen: :twisted:
Last edited by Mandrake on 08 Sep 2015, 20:04, edited 1 time in total.

Hell Razor5543
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Re: Simon's new Xantia V6 blog

Post by Hell Razor5543 »

You just gave it a long Italian tune up!

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Hell Razor5543 wrote:You just gave it a long Italian tune up!
Maybe, but it wasn't being driven hard as such - I had two passengers who would not have taken kindly to a lot of foot to the floor stuff.... so while I drove briskly in some places like quiet stretches of motorway I also spent a lot of time keeping to the speed limit and following other cars at a constant speed. I wouldn't have classified my driving style yesterday as italian tuneup. :mrgreen:

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Re: Simon's new Xantia V6 blog

Post by Hell Razor5543 »

No, but you blew the cobwebs out. I would suggest you do that on a regular basis, to keep her in fighting fettle.

Using a very poor analogy, the racehorse Yeats managed to make history by winning the Royal Ascot Gold Cup 4 times in a row. One thing the trainer did was to enter him in a race a few months before Royal Ascot week. He was not expected to win, or even do well; the idea was to get him back into the feel of racing. It worked, he made history.

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Managed to fix the cruise control yesterday :) Or at least get it working again, as the repair uncovered a previous bodge job! [-X

After doing battle with the two rusted bolts with a junior hacksaw and a drill (no grinder with cutting disk for me - yet!) I found the problem fairly quickly - the pipe circled in blue had split:

Image

After cutting off the split part of pipe I soon found why it was split - the pipe doesn't seem anywhere near big enough to push over the spigot. :shock: Even after applying some grease and stretching it as much as possible I was only just able to get it on as far as shown in the picture... I don't know how long it will last or whether it too will split. There seems to be a join in the pipe indicated in the yellow circle - is that joint and the seemingly too small pipe original or has someone replaced it ?

Before I even found the split pipe I immediately noticed the bodge circled in red. :twisted: Yes, someone has shoved a piece of hose blocked off with a screw onto the end of the dump valve to defeat it - there shouldn't be a hose there at all, presumably the dump valve has failed open (as it had on the Silver problem child) and instead of replacing the valve for £30 they decided to disable it... #-o

There are actually two valves to release vacuum - the "dump valve" which has been disabled here, and a smaller slow release valve that is used to reduce the throttle opening smoothly during cruise. The difference between the two is when the slower valve (on the pump body) opens the throttle closes slowly, while the dump valve makes it snap instantly shut.

The idea of the dump valve I guess is so that when you touch the brake pedal to disable the cruise control the throttle instantly snaps shut so that you're not fighting the brake with the throttle still open...

How it is now there is a slight delay in the release of the throttle when you cancel the cruise control by touching the brake. In theory this is a little bit dangerous as the dump valve is there for safety reasons, but I can't honestly say that I had noticed it's absence for the few months that the cruise control was working...

So I will replace the dump valve at some point but for now the cruise control is back working and is a marvellous thing for navigating quiet rolly polly motorways like a trip home from Edinburgh late last night. :-D

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CitroJim
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Re: Simon's new Xantia V6 blog

Post by CitroJim »

Excellent Simon, the split on the blue circles is the normal place for them to go and you're right, the pipe does seem too slow.. On my original V6 I did a mod to include a reducer so a bigger pipe went on the spigot and then reduced down to the main pipe.

It was still good when I broke the car a few weeks ago...

That bodge on the dump valve was dangerous!

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Well I'm none too chuffed. :evil:

After parking in a train station car park for the last month I was on the way home in the dark the other night when I realised that the passenger side mirror was folded completely in. I couldn't stop to fix it and then forgot about it when I got home. The next day I didn't remember it until I was in a hurry to go somewhere so I leapt out of the car, turned it back to the right angle and drove off, blissfully unaware of the true extent of the damage.

Only a day or so later did I notice that the back of the mirror seemed to be the "wrong colour" #-o

Image

It appears a plastic piece has come off ? As well as the frame at the bottom having a big chunk missing. Here is the other side for a colour comparison. (Sorry, it's a bit dirty!)

Image

The car is Silex grey, anyone know what colour the back of the rear view mirrors are and whether any second hand parts are available to repair it ?

Also what holds it on ? There didn't seem to be any adhesive or clips holding the plastic on...

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Stickyfinger
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Re: Simon's new Xantia V6 blog

Post by Stickyfinger »

I have a spare if you cannot find the correct coloured one mate, just ask if you need........

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Is that just the missing plastic piece you have, or do you have the frame around the bottom that is broken as well ? It's the passenger side BTW.

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Re: Simon's new Xantia V6 blog

Post by Stickyfinger »

Both, I have a mirror with the gubbins removed, I will check the side, if not I have a complete one, they are easy to strip down and rebuild.

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Mandrake
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Re: Simon's new Xantia V6 blog

Post by Mandrake »

Hi Alasdair,

I haven't forgotten about the mirror - but car repairs (especially non essential ones) have had to take a back seat for the moment, probably until the spring but I will get back in touch regarding a mirror.

Thanks. :)