Simon's new Xantia V6 and Leaf blog

[Mandrake]

We need to treat our Simon to a vernier caliper. Xmas (and maybe a birthday) approaches...
You're right about those LH seals - they do look scruffy.

I have a digital vernier caliper already. Just not at work where I am at the moment...

[bobins]

........poor bonding to the washer etc and the surface finish/plating of the washer is poor and variable from one seal to the next too. (Also I can't find out from the seller what the plating is - no reply! Can anyone guess what the plating is on the ones on the left from the colour ?)

My guess would be : gold coloured Sharpie pen

[Mandrake]

Today I fitted the banjo washers and changed the gearbox oil. To do the oil change the oil needs to be up to 80 degrees to drain and check the level during refilling so we used the car to run some errands that we would normally use the Ion for. During that drive the gearbox was still playing up significantly in 2-3 and 3-4 upshifts and felt a little bit "twitchy" and eratic overall.

The oil level wasn't low so it can't have been leaking too much, however there was still enough of a leak to leave the side and underneath of the gearbox quite oily, and this was even after I wiped it clean a few weeks ago:

Despite fitting brand new aluminium washers about 2-3 years ago they were badly pitted and eroded again, enough to leak:

In my opinion the outside diameter of the original factory washers is too small, causing them to be recessed well below the level of the housing, possibly allowing salt water to accumulate in the crevice thus formed. (Also it means the washer has very little "meat" to seal on, so it doesn't have to erode far along the surface before leaking - both have a spot where it has erroded nearly all the way across the narrow face) The OD of the originals measured 18.7 and for context the copper washer (the same size I used as an emergency banjo washer on the previous Xanta) shown has an OD of 20mm, and the dowty seal has an OD of 22mm. All have the same ID which fits the 14mm bolt snugly.

I was worried that 22mm OD would be too big, however it actually works out to a perfect fit with the washer neither protruding or being recessed like the original. This is the new washers after having been for a longish drive - perfectly leak free, and hopefully it will stay that way with the viton seal and the zinc plating will protect them.

Does anyone know if there is a wheel arch cover missing here ? That banjo joint seems awfully exposed to road debris and salt, but both my V6's have had it wide open and exposed like this when I got them...

As for the oil itself, I wasn't too happy there. Despite the car having a hot flush not long after I got it, and another oil change by me about 2-3 years ago and not doing much mileage (only 20k over the 5 years I've owned it) the oil was in a terrible state. Pitch black, thin and runny like water compared to new oil, and when I caught a 1 litre sample in a measuring jug as it was draining and tipped it out I found significant quantity of particulate matter:

Whatever the particulates are (presumably clutch material) they're not magnetic. I compared a sample of the oil I drained with the samples of the oil from my previous V6 which I still have in little test tubes and it's actually blacker than the first drain I did on the other car, which is not what I was expecting given that I thought this gearbox was in pretty good order.

Afterwards I took it for a drive to let the oil circulate and fully mix with the old oil then did an autoadaptive reset then drove for about another 20 miles to let the ECU adapt. After that short amount of driving my conclusion is there hasn't been much improvement so far. It does seem to change gears a bit more smoothly in general and doesn't seem "twitchy" anymore but the 2-3 and 3-4 upshift flare that I was hoping to erradicate is still there intermittently.

The torque converter lockup seems to be working smoothly (unlike the previous V6 whose torque converter was stuffed) and when it's in gear there is no slipping when you apply power (unlike the old V6 which would flare even while in gear) so my gut feeling is that the clutches are ok and the flare up is caused by one of the solenoids sticking intermittently probably due to contamination.

The oil was so dirty that I think I'm going to have to do another change in a month or two given that the oil change only changes about half the total oil in the box so the oil has only been 50% diluted with fresh oil. If there's significant contamination of the oil then a single oil change isn't enough to fully cure symptoms. I remember on the previous V6 when the oil was really bad it actually took two oil changes before I noticed any change in its symptoms, and three changes before most of the symptoms were reversed. (For a while anyway)

I added some Lubegard Platinum as part of the oil change as I had good luck with that on the previous gearbox, one thing it claims to do is help free sticking valves in the valve block but that may take a while to happen, and the car has only done 20 miles since the oil change. So a lot more driving and another oil change is probably needed before any definite conclusion can be reached about whether the symptoms can be reversed or not.

During the test drive I monitored the oil temperature of the gearbox continuously with the Lexia and I can report that the temperature is fine - it tracks very closely with coolant temperature and when you do push it hard and it rises a bit it then drops back to within a couple of degrees of the coolant temperature very quickly when you ease off, which means the heat exchanger is working well to cool the oil. (unlike the blocked heat exchanger in the old V6 where the gearbox oil overheated under load and stayed hot for a long time even after you eased off)

In any case I'm going to put it in for an MOT soon - I remembered that the wiper blades are also stuffed and very streaky on a partly wet window so I may as well swap them over before the MOT as well.

Other than this damn intermittent flare up on 2-3 and 3-4 up shifts the car is driving like a dream. I'll be gutted if I can't get the gearbox issue sorted eventually.

[Mandrake]

After more driving today I'm starting to suspect that there could actually be an intermittent fault with the torque reduction control line from the gearbox ECU to the engine ECU after all. This is a dedicated line between the two ECU's that from memory sends either a high/low or simple PWM signal.

The purpose of it is that just before a gearchange the gearbox ECU signals to the engine ECU to cut torque dramatically, which it does by retarding the ignition timing by about 20 degrees. So even though you keep your foot down during the gearchange it's as if you'd lifted your foot.

The gearbox ECU then ramps the pressure to the new clutch up and the pressure to the old clutch down and after the gear change completes (about half a second) it signals to restore engine torque to normal. This is so that during that period of clutch slip and overlap the engine torque is reduced to reduce strain and wear on the clutches and give a smoother change.

This feature gives this auto box a distinctive "manual-like" gear change characteristic under strong acceleration where it sounds like you've lifted your foot off the throttle for the gear change, both for up shifts and also kickdowns, which have a sort of double declutching sound to them when it's working properly.

When you're accelerating under throttle and you get a gear change you normally hear that half second lull in the "engine power note" where the engine becomes a lot quieter because it's not putting out much power. What I've noticed is that when I get the really blatent flares during an upshift the engine note does not quieten down like it normally does, it remains noisy like it's still putting out full torque demanded by the throttle. Busted!

Likewise during a kickdown it sometimes lacks the "double declutch" sound where you should get a momentary burst of engine note when you first mash the throttle, followed by a lull in engine note for half a second as it changes gears then the engine note again.

Full torque during the gearchange is very likely to case the engine rpm to flare up and certainly won't be conducive to a smooth gearchange, and if it's happening all the time will eventually wear the clutches prematurely as they're not designed for full power during the slipping/crossover period.

This would all sound quite far fetched if it wasn't for the fact that Citrojim already fixed an almost identical problem on Trainmains ill fated Red Xantia V6! I don't recall the exact symptoms but I think the gearbox going into limp mode due to clutch slip may have been one of them - clutch slip provoked by constantly changing gears without the normal engine torque reduction operating.

From memory Jim found that there isn't a single wire run between the ECU's, but that they are two separate wires with a poor quality crimp connection between them part way along inside the wiring loom trunking, and that crimped joint had become corroded and intermittent, thus the intermittent nature of Trainmain's V6 problem.

Unfortunately that's all I can remember of that issue, as it was about 5 years ago now - I can't remember if Jim ever detailed exactly the path the wire runs and where in the loom the spice is he repaired, or for that matter whether the details were discussed in Citrojim's blog or Trainmans blog. Can anyone help me find the posts in question ? They date back to approximately 5 years ago. Hopefully Citrojim and/or Trainman are reading this and might rembemer!

I think it's well worth me trying to bypass this wire - rather than trying to find the splice and repair it, I'd run a completely new wire through the trunking between the ECU's. I already know I can thread another wire into the cable bundle going into the engine ECU connector and solder it to the pin on the inside of the plug as the connector can be disassembled and I've done that before. I'm not sure whether the same can be done on the gearbox ECU connector (the ECU is under the battery tray) and whether that connector can be disassembled but I would think so.

The route that I suspect the original wire follows, or at least the route I would follow for my replacement wire is below:

Looks like a pretty easy run of trunking to thread a new wire into - once the battery and battery tray are removed (which is necessary to get to the gearbox ECU connector hidden underneath) and the air filter and top and side plastic covers are removed from the engine the entire trunking run should be fully visible from end to end.

Before I can do so I need to check the wiring diagrams to find exactly which pin number at the engine ECU end connects to which pin number at the gearbox ECU end. Unfortunately Sedre only covers the Series 2 Xantia and I am not sure that the S1 V6 wiring between the ECU's is identical - it's quite unlikely in fact when they use different immobilisers! (Thus the pinouts for the engine ECU are almost certainly different)

So is anyone able to help me with the wiring diagrams for both engine ECU and gearbox ECU for a 1997 S1 Xantia V6 so I can positively identify the torque control line ? For the sake of replacing a wire, it seems like a good idea to at least rule it out as a posible contributor to the gearbox problem.

[white exec]

Hi Simon,

S1 V6+HP20...

[Mandrake]

Hi Simon,

S1 V6+HP20...

Hi Chris,

Thanks for that, however the resolution is a bit low and blocky such that I can't positively identify some of the numbering. Also that only seems to have the wiring diagram of the engine ECU but not the gearbox ECU ?

[white exec]

Hi Simon,

Herewith the HP20 wiring pages...

I'm having the same problem of low res image on my iPad here.
On the PC, first magnification of the posted JPEGs is not good, but second click magnification is better.

The originals are high-quality PDF scans, but we're unable to post PDFs as attachments at the moment.
Am asking Mike/Marc to have a look at this.
Bear with it.

[Mandrake]

Thanks Chris - PDF would be much preferred and appreciated.

Strange - as I have attached PDF's to the forum before, (Sedre exports in fact) but it might have been back in the days when we had to use our own file hosting services...

Does the forum still support zip attachments ? Maybe just zip them all up.

[xantia_v6]

We are investigating improvements to the hosting of wiring diagram images, in the men time, here are links to the diagrams (Xantia Mk1 V6 4HP20) which jim posted previously:







Note that I think that Chris may have posted the MK2 diagrams which have some differences, particularly around the fusebox.

[white exec]

As a workaround for those attached JPG images, I found this morning that a better result was to Save, Paste (into Word etc) and Print the page, b/w at A4. Even an enlarged section remained legible.

[Mandrake]

Thanks to Chris for emailing me the high resolution original PDF's.

I've had a look through and it appears that the existing torque reduction control wire travels from the engine ECU through the connector on the front right wing bulkhead and through the infamous bundle of wires below the radiator to get around to the other side of the car.

As I've already had a major 12v power supply wire fail in that bundle under the radiator that had to be bypassed via another route, and that bundle is a known weak spot on Xantia's in general I think it's at least plausible that another wire could be about to fail or failing on me.

There are also three other signal wires (all digital TTL 5v signalling) between engine and gearbox ECU's that are critical to smooth operation of the gearbox.

1) Engine RPM sent from engine ECU to gearbox ECU - the gearbox ECU needs this to measure the slip across the torque converter as it has a sensor AFTER the torque converter (the "input" sensor) and another one after the final drive (road speed sensor) but does not have a sensor for the input to the torque converter - it relies entirely on the speed measurement passed from the engine ECU.

Measuring the slip across the torque converter is critical for the ECU to balance the pressure to the torque converter clutch - if this signal becomes intermittent the torque converter lockup will misbehave at the very least.

2) Torque output from the motor - the engine ECU calculates (estimates) the current output torque based on many factors such as throttle position, ignition timing, coolant temperature, etc etc and provides this figure to the gearbox ECU. The gearbox ECU uses this torque figure to help regulate clutch pressures when controlling the torque converter or shifting gears. If this signal is disrupted gear changes are likely to be very rough and torque converter lockup will misbehave.

3) Throttle position - the engine ECU sends the throttle position sensor data to the gearbox ECU - this is used of course to modulate shift points, provide kickdown etc. If this signal is disrupted shift points may become erratic and kickdown may not work properly.

Another interesting thing I've discovered reading the 4HP20 manual (again, for about the 3rd time ) is that the torque control line which is used to retard the timing during a gear change is also used to inform the engine ECU whether the gearbox is in P/N or Drive.

Why is this important ? Because for whatever reason, the engine ECU deliberately retards the timing while the car is in neutral. I don't know why - doesn't make sense to me, but that's what the documentation says, and it implies that it modulates the timing to make the idle as steady as possible. So if there was a problem on this control line then potentially the engine ECU could think the car was in P/N while actually being driven and thus retard the timing and cause a loss of power.

As all 4 wires are so critical to proper functioning of the gearbox I've decided I'll try to bypass all 4 of them if I can get 4 small wires into the existing trunking. I think I've found an alternative, shorter, easier route in the bundle that goes across the top of the engine and around the front of the air filter assembly, so we'll see how that pans out.

I'll just piggyback solder the wires on the terminals inside the connectors and leave the original wires connected as well if possible. I know there's room to piggyback in the engine ECU connector but I haven't looked inside the gearbox ECU connector before.

[Mandrake]

I should probably add that after a few hundred miles driving after the oil change I'm now starting to see significant improvements in the overall behaviour of the gearbox.

Unfortunately the actual up-shifts are still intermittently flaring (which I'm now thinking might have an electronic cause hence the whole wiring repair diversion) but in other regards the gearbox is operating a lot nicer, in particular the torque converter lockup is really smooth and sweet now - it was just starting to give the slightest shuddering on occasions before the oil change, and could be a bit abrupt in locking up when you accelerated slowly in 2nd. Now the lockup transition is so smooth and gradual you almost can't notice it, and no traces of any shudder. Torque converter shudder even if very minor is usually a sign that the oil is well past its best and that its friction modifiers have worn out. So even if a wiring glitch turns out to be responsible for the intermittent flare on up-shift the oil still desperately needed changing! How much of the smoothness is the clean oil from the oil change and how much is the effects of the additive is hard to say...

[Mandrake]

Well she passed the MOT for another year...

The only written advisory was for slight leak of exhaust gases near the front of the car. I had noticed a slight noise there myself but couldn't find the source.

I did get a verbal warning about marginal rear brake performance again despite the new discs/pads, calipers being out, pistons lubed etc...and from driving the car I'm of the opinion that there is nothing wrong with the brakes. There is no lift at the rear under braking and the stopping performance of the car is terrific.

We had another chat same as last year about the rear brake load limiting system, and that it limits the maximum brake force to a low level when the car is unladden but I don't know if he was convinced. At the end of the day he said the test requirements are set down and if it doesn't pass it doesn't pass, and that if I thought adding load in the rear would help it pass the test better then I should do so next time, so I will!

I was considering doing it this time and lifting a couple of paving slabs into the boot however I've done a lot of laminate floor laying and other physical work recently which has done in my back and knees a bit, still recovering, and I think any attempt to lift paving slabs at the moment would finish off my back!

I haven't had a chance to try the bypass wiring for the gearbox ECU yet - a combination of bad weather and lamite floor laying has thus far prevented me, but I will look at it as soon as I can...

There is very obvious improvement in the behaviour of the gearbox since the oil change and additive which has gradually improved further with driving, I wouldn't say it's normal by any means yet as the shifts are sometimes still a bit hard or sometimes have flare up during an upshift, but it's certainly an improvement. I'm now not quite as fearful of imminent demise of the gearbox, however I'd like to see further improvement still. I'm hoping a second oil change (with the same proportion of additive) and the wiring "reinforcement" I have planned will get it back to the point where it's operating close to normal behaviour for a gearbox of its age.

BTW looking at the MOT sheet has pointed out to me that the Xantia has only done 1600 miles since its last MOT, while the Ion has done 13,000 in the same period of time! Cushy life that Xantia gets...

[myglaren]

Good news on the MOT.
Could be worth chucking a load in the boot next time - or even ask if they will run a quick test now you have just done the brakes, confirm if it makes a difference.
I always used to in the GS but haven't bothered since.

[Mandrake]

I used to have to put a load in the boot of my Citroen's for MOT equivalent in New Zealand as the testers didn't understand or accept how the system worked, looks like I'll have to start doing it here too... With no load it was always only a marginal pass in NZ as the regulations assumed the rear brakes could always apply full braking force.

Forgot to mention in my previous post that so far the gearbox Banjo joint is absolutely dry without even the slightest wetting of oil. So that's a big thumbs up for the zinc plated viton rubber dowty seals, so far anyway! And being zinc plated they should hopefully last quite well. If anyone ever needs any for a 4HP20 I have a bag of 8 left over...