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

[isisalar]

The noise is a sort of chirp as the gears engage. No rumbles or any effect other than the noise which is I am told is an indication that the clutches are wearing. It only shows up when the box is very hot. Trans lube works wonders, give it a try.
Cheers
Paul

[Mandrake]

Hi Paul,

Doesn't sound like the same issue then, mine never makes funny noises when changing gears and the gear changes are nearly always smooth except for the occasional shift down from 2nd to 1st at a junction if you happen to floor it at a near crawl just as its changing down.

[Mandrake]

With an AL4 the shudder arrives as pressure regulation starts to become faulty. I can readily imagine this applies to the ZF boxes as well, the main difference being their electrovalve design is perhaps more readily "flushed" than a Siemens item.

Could well be.

One major difference between the AL4 and 4HP20 though is that the AL4 lacks a controlled slip mode for the torque converter clutch - its either unlocked or fully locked. (Apart from the brief transition between the two for a fraction of a second of course)

From what I've seen on the Lexia the 4HP20 seems to spend a lot of its time in the controlled slip mode where its regulating a slip of about 50 rpm. The only time it really goes into full lockup is if you accelerate hard (and it has decided not to open the clutch instead) or when its overheating. For most normal driving once it "locks up" its actually in the controlled slip mode not full lock up.

From what I remember it was always the controlled slip mode that made the "groaning noise", not full lockup, so the groaning was probably just the ECU failing to regulate the slip smoothly due to either pressure control problems as you suggest, or the wrong frictional characteristics of the contaminated oil.

Personally I think the controlled slip mode is a bad design decision especially for a high torque rated gearbox and probably leads to the clutch wearing out a lot faster than it would with a simple two state unlocked / full lockup system, all for dubious benefits, especially given the difficulty and complexity of regulating the slip in the face of constantly varying engine torque and loads. Possibly a case of ZF being a bit too clever for their own good...

In theory the ECU could be re-programmed to eliminate or drastically restrict the use of the controlled slip mode in favour of full lockup, which would undoubtably prolong the life of the clutch greatly and probably give the acceleration a bit more of a snappy feel to it as well...possibly at the expense of a slightly less smooth overall experience. If anyone could figure out how to reprogram it that is...

[Mandrake]

A little observation somewhat at a tangent to the various problems recently. I was looking through my MPG figures and have seen a recent improvement

The highest MPG I've ever seen was 32.8 during an 800 mile road trip last July (before all the engine/gearbox problems manifested) but other than that I've generally only ever seen an average of 19.8 with mixed driving that includes a lot of short trips etc...never above 20.

In the month just before changing the badly fouled FR7DC+ spark plugs I saw a particularly abysmal 17.3MPG averaged over 350 miles.

The very next MPG figure after changing the spark plugs without changing any driving habits and still on the same BP unleaded fuel I did 21mpg, the first time its ever gone above 20mpg for mixed driving.

Next time I put Shell V-Power in, this time it did 22.9MPG on mixed driving! A slight cheat perhaps in that 120 miles of the 286 miles of that fill up was done on one day with a mixture of motorway and windy country road, but I was NOT light on the throttle or in any way trying to drive in a fuel conserving way, and the rest of the tank was used with lots of short trips as per usual.

Too small a sample size to tell for sure of course but I've got another tank of V-Power in at the moment so I'll see what it does this time as I'm unlikely to be doing any long trips this month, but rather lots of short trips moving house.

What's interesting is that although the higher octane fuel is about 6% more expensive per litre, the improvement in MPG (if accurate) is 9% so it actually works out cheaper, and at the same time the car runs much better on the higher octane...

It looks like using 95 octane petrol on this engine is actually false economy...

Quite chuffed really as I was very disappointed almost despondent when I calculated 17.3MPG a couple of months ago, so to see it go up to 21MPG then 22.9MPG with sorted spark plugs and better fuel respectively is quite satisfying.

[Ben82]

Maybe I should try a tank of 98 octane in mine when I get back to normal weeks.

Will probably need a mortgage for it though as its rare over here and not advertised but I know 1 garage that has it

I do not believe for me though I'll see enough improvement to warrant it.

For the past couple of months, mine has been running on around 45-50% e85, without issue. Cost saving is huge though, e85 is about 96p per litre and 95 octane is ~£1.43 per litre. So saving about £17 per tank. Realistically it's supposed to drink more with e85, but I have has on a 300km round trip got the best recorded fuel consumption of 9.9l/100km (about 28.3mpg) with E85. Had a fair amount of town (and some fun) driving so average is about 12.7l/100km (about 22.2mpg) on my current tank. Even for 95 octane it would need to average at least 10.5l/100 to break even (if I have my math correct).
From what I've read about E85 is its octane rating is higher anyway.
Obviously all academic for you as e85 is rare in the uk.

It is interesting to see what mpg others get in their V6s though.

[CitroJim]

It is interesting to see what mpg others get in their V6s though.

It will be. I'm sure I get better than your even your highest mixed figure Simon. Unless you’re particularly Xac-footed what you get appears very low indeed...

[Northern_Mike]

Even I got mid-20s out of mine over the brief time I had it and I probably make Xac look light-footed..

[Mandrake]

It is interesting to see what mpg others get in their V6s though.

It will be. I'm sure I get better than your even your highest mixed figure Simon. Unless you’re particularly Xac-footed what you get appears very low indeed...

Well I have no idea how speedy Xac is, I'm not always lead footed, particularly around town I'm not, more so on a country road. I'm no Peter N anyway.

You can see my disappointment in never being able no crack 20 in mixed driving before, it stubbornly stayed below 19.8 even without a lead foot, and was sometimes down to 18, so to see well over 20 twice in a row is pleasing.

By comparison my 2 litre (auto) Xantia wasn't great on fuel either, on 96 octane in mixed driving it did about 8.4 km/l (23.7mpg) and the best I ever saw on a trip (all highway speed) was 11.1 km/l (31.3mpg) so the V6 managed to beat it on a trip (32.8mpg last year) but has been a lot lower on mixed driving, I just assumed that's how they are...

If I can get it up around 23mpg its not much worse than the 2 litre considering its 200Kg heavier.

[CitroJim]

Xac is very speedy and leaden-footed... He no longer has an accelerator pedal. He now has a switch labelled 'Idle' and 'WOT'

Seriously, with moderate driving like mine you should crack 35 on a run...

Round town I'd expect mid to high 20s...

[addo]

So, we have a good spark.

We have heavy fuel usage, so we know it has good fuelling ability.

It's sluggish at times, even when lightly laden, and runs towards hot.

[Ben82]

My biggest issue actually stems from the sequential feature.... if someone is trundling along the country lane I frequent, I often cannot resist kicking down a gear or two to overtake, when I could probably easily just as well overtake in 4th.
The purr at 5000+ revs the engine makes is lovely So that quickly racks up the average.

Simon do they not use l/100km down under? I got confused by your figures then realised it was km/l (though for the longest time l/100 confused me as it seemed so unnatural).

Jim, has Xac replaced his Accelerator pedal with a DS Brake pedal?

[Mandrake]

My biggest issue actually stems from the sequential feature.... if someone is trundling along the country lane I frequent, I often cannot resist kicking down a gear or two to overtake, when I could probably easily just as well overtake in 4th.
The purr at 5000+ revs the engine makes is lovely So that quickly racks up the average.

I know what you mean Ben, my favourite is kicking down to 3rd at around 60-70mph to overtake which puts it right at the sweet spot around 4000 rpm Not only does it purr nicely there its also maximum torque and (when its running properly) gives the acceleration a serious kick in the pants, whether you're on the flat or going up a hill doesn't seem to matter.

Simon do they not use l/100km down under? I got confused by your figures then realised it was km/l (though for the longest time l/100 confused me as it seemed so unnatural).

I don't know what the "official" unit is in NZ Ben, although NZ is fully metric since the late 60's (yes even road signs you die hards in the UK that are still clinging to mph ) all three are in use in casual conversation, MPG more so by the older generation, I generally used kilometres per litre as it makes sense to me - I put a litre of fuel in (with fuel sold by the litre at the pump) how far will I go ? The same as MPG but with metric units. Litres per 100km seems a backwards unit to me, with an arbitrary choice of 100km. (why 100km in particular ?)

I think litres per 100km is more universally used in Australia than NZ.

[Mandrake]

So, we have a good spark.

We have heavy fuel usage, so we know it has good fuelling ability.

It's sluggish at times, even when lightly laden, and runs towards hot.

Really addo, still with the blocked cat ?

I think you've got the timeline and facts a wee bit mixed up.

Good spark - yes, now. When the plugs were fouling a month or two ago and it was running really bad, getting 17mpg clearly not then. Since the new plugs went in the MPG jumped straight up to 21MPG for the same driving habits and the performance jumped up too.

Not only were the FR7DC+ plugs that I put in last time one heat range too cold, the NGK plugs that were in the car before that (which came with the car) were also one heat range too cold once I deciphered the codes and found a compatibility table to cross check them. (In fact the "recommended" NGK plug for the ES9J4 which is spat out by most websites when looking up based on engine, when properly cross referenced is actually a heat range colder than the original factory Bosch type that I have fitted now. )

Whether it was just the combination of lots of short trips on plugs that were a heat range too cold that caused the fouling, or whether there was an additional contributing factor I'm not sure. One possibility is excessively retarded timing and over fuelling - which the ECU will do under acceleration in response to knock sensor input, both of which will increase fouling tendency due to excess fuel and the plug running colder with more fuel and retarded timing. (Could be related to the knock retard issue that seems fixed now) So far I've done about 400 miles on the new plugs and no signs of fouling yet.

Heavy fuel usage - yes, but that was there ever since I've had the car, even when I didn't have anything to complain about the performance. The first time its done above 20MPG in mixed driving is after the correct spark plugs have been fitted.

As for "runs towards hot", where do you get that impression ? I speculated the gearbox might be running hot, and that there might be a heat exchanger problem, but I know the engine isn't overheating because I've been running with the radiator cap loose for many months now due to a pressure leak in the seam of the expansion bottle, and its never boiled despite not running pressurised, even after being thrashed.

My dashboard temperature gauge is a bit flaky and not to be trusted (usually reads too low) so I tested the temperature very carefully with the Lexia under a variety of driving conditions - at all speeds above 30mph regardless of thrashing it hard up hills etc the coolant stayed between 87-89 degrees. Only when I slowed down to a stop did it then rise to 97-98 when the fans kicked in. So I don't consider this "runs toward hot" at all.

As for sluggish sometimes, I was definitely reading knock related retard on the Lexia during normal driving until I both upped the fuel octane and added the tappet additive. The tappets were very noisy before, a few weeks later and they're still almost silent, whether the noisy tappets were being picked up by the knock sensor or it was just the fuel I don't know for sure but I've now proved to my satisfaction with the Lexia that no knock sensor based retard is being applied even under full throttle.

I've also monitored the "Engine Torque" figure from the gearbox ECU recently, which is calculated by the Engine ECU and sent to the gearbox. Under full throttle at 4000 rpm its reporting 260Nm of torque, which I believe is spot on and I can see over 230Nm with full throttle over a wide range from about 2500-5000rpm.

Now I don't know how much this figure is actually measured, and how much its "assumed/predicted" torque based on inputs to the engine, such as rpm, throttle opening, map reading, timing advance, injector pulse time etc... so maybe it just thinks its producing that torque but its not...without a dyno I can't say for sure. But as far as I can tell since the last round of changes the engine is running normally.

I hate to say it but I'm gradually coming to accept that the torque converter is the source of any remaining intermittent power issues.

I've been carefully observing the operation of the torque converter and its lock up clutch (both audibly and with the Lexia) and it is most definitely doing strange things, but only intermittently...

There is no doubt that it's having difficulty regulating the controlled slip properly (worse sometimes than others) and may be having difficulty locking up under high torque as well. It's quite clear from the engine note/rpm that as you accelerate and it transitions from unlocked to controlled slip that its making hard work of it as the transition sometimes takes a couple of seconds when I would have thought it should take a fraction of a second.

Whether the linings have broken up, are down to the metal, or there is a pressure regulation problem I don't know, I just know that it isn't working properly and it has been getting steadily more erratic for the last 3 months or so. The additional engine related issues at the same time like fouled plugs have just confused the issue.

It's slow to respond in controlled slip mode when increasing the throttle - the engine revs give a little surge for about half a second and then drop back again, and the state on the Lexia switches from piloted to open then back to piloted again.

It's also shuddering noticeably when trying to accelerate at low (1500) rpm in the controlled slip mode, but strangely not all the time, some days it doesn't do it.

One important thing I've discovered while testing with the Lexia is that where it shows the torque converter lockup state (open, piloted, firm) this is NOT the ECU's desired state, its simply an indication of how much slip is actually occurring at a given moment, measured across the torque converter. Less than 50 rpm it shows firm, 50-100 rpm (approx) it shows piloted, more than 100rpm slip it shows open, even if the clutch is partially engaged.

To see what clutch state the ECU is trying to achieve you have to look at the electrovalve "pressures" (actually current) for proportional electrovalve EDS3, if the current is 159mA it's commanding the clutch to open, 768mA its commanding full lock up, any intermediate value its attempting to regulate controlled slip. The valve of current in controlled slip mode should give an indication of how much force its trying to apply to the clutch to control the slip. If its always near the top end of the range it might suggest the clutch is worn out and taking more hydraulic force to get the correct slip for a given torque, and it may be running out of operating range at the top end because of it, like a manual clutch with not much bite left. I really need to have a close look at this value during a test drive I think.

I don't think any of the main gear changing clutches are slipping though as gear changes seem normal and it should log a fault if it detects excess slip between the turbine and differential speed sensors for a given gear ratio.

Another thought that has occurred to me as well, is that the one way roller clutch that supports the stator could be worn out. If the roller clutch is slipping and allowing the stator to free wheel when in open / torque multiplication mode then you'd loose the torque multiplication and it would then act only as a fluid coupling with power loss and no torque multiplication, which would drastically cut the acceleration in open mode...

[larppaxyz]

Hi,

been reading this thread for a while. There is known flat-spot issue with ES9J4, i actually have on in my Coupe 406 and also suffer from this. Some people say that it's normal, but it's not, there is dynochart laying around some where (can't find it now) that proves it's a real issue. In my case this mean p**s poor power on low RPM and only when ECU kicks into different mode at 4000 rpm it goes (exhaust sound changes and everything). Every now and then it works like it should but usually doesn't. I have replaced most of the sensors without any real difference. Sometimes when i just do random things (like unplug some connector and wiggle some wires) i might start to work. One symptom is bad idle and if i try to keep revs at let's say 1500, rev go up and down +-200 rpm. I also feel that my torque converter really get's confused by this issue.

One thing i haven't tried yet is to cut wire that tell's engine ECU to retard timing. It's torque reduction feature of transmission that is used to take out power when shifting gears. It's single wire from transmission ECU to engine ECU and cutting that could help trace if problem comes from transmission or engine. Can't remember which pin it was.

I think earthing of engine and transmission should be checked too. That is something that could explain when thing sometimes work.

Air in cooling system can cause very interesting issues also, because engine tempereature sensor is fitted so that it may not touch coolant at alla if there is air in system (causing sudden sputters and even may cause engine to die when thermostat open suddenly and there is burst of water onto sensor). So check that.

Tapping valves tell me when to change engine oil. On my engine, there is no tapping at all.

Then there is this oil on spark plugs thing, but i think you already checked that.

[Mandrake]

Hi,

been reading this thread for a while. There is known flat-spot issue with ES9J4, i actually have on in my Coupe 406 and also suffer from this. Some people say that it's normal, but it's not, there is dynochart laying around some where (can't find it now) that proves it's a real issue.

Hi,

Thanks for taking the time to read and respond to my thread! Its reassuring that I'm not the only one who has experienced this odd array of symptoms! Perhaps if we compare notes we might be able to pin down the cause.

You'll find the torque and power curves for the ES9J4 here:

http://club-xm.com/forum/index.php?showtopic=2873&st=0" onclick="window.open(this.href);return false;

In my case this mean p**s poor power on low RPM and only when ECU kicks into different mode at 4000 rpm it goes (exhaust sound changes and everything).

Yes this is exactly what I experienced when the engine was running at its worst a number of months ago - p**s poor power low down but upon reaching 4000 rpm it would instantly zoom away like a scalded cat. Always at the exact same RPM, and as you say the exhaust note changed too.

Mine doesn't seem to be doing this anymore, but the trouble is I've done so much work on it since then that I don't know what I did that fixed it. My suspicion is it is either ignition related or knock sensor related.

Have you fitted new spark plug leads to the rear bank, and new spark plugs all round ? What type of spark plug are you using ? I'm now using Bosch FR8KDC and they are working better for me than either of the previous two types.

Every now and then it works like it should but usually doesn't. I have replaced most of the sensors without any real difference. Sometimes when i just do random things (like unplug some connector and wiggle some wires) i might start to work.

Exactly the same here, most sensors replaced or ruled out, no real difference, however sometimes after random work on the engine (disturbing things) the performance will be much better for a while then be poor again. Almost like a bad electrical connection somewhere.

One symptom is bad idle and if i try to keep revs at let's say 1500, rev go up and down +-200 rpm. I also feel that my torque converter really get's confused by this issue.

Yes I've had this as well - a few pages ago you'll see a video I recorded of the RPM going +/- 200 rpm when trying to hold it steady at 1500 rpm. At the time I correlated it with the torque reduction ignition retard figure, which was going to 15 degrees of retard each time the rpm dropped, and back to zero as it rose again, although I don't know what was causing it.

Since that time I've fitted new spark plugs, added a tappet additive to the oil which has quietened the tappets, and changed from 95 to 99 octane fuel, since then it's no longer showing a fluctuating idle at 1500rpm, but I don't know for sure if any of these things are the reason.

What octane fuel are you using ?

As for "bad idle" do you mean that when you come to a stop (or sometimes when starting a hot engine) the revs will drop to try to stall, then surge up, then drop to try to stall, sometimes up to 3-4 times ? Mine has done that intermittently for a long time, and I can't find the cause of that either.

Are you sure your torque converter is not having problems ? Have you ever heard it make a "groaning / grinding" noise under load at 1500rpm ? Have you done any oil changes on the gearbox ?

One thing i haven't tried yet is to cut wire that tell's engine ECU to retard timing. It's torque reduction feature of transmission that is used to take out power when shifting gears. It's single wire from transmission ECU to engine ECU and cutting that could help trace if problem comes from transmission or engine. Can't remember which pin it was.

It's pin 51 on the gearbox ECU which goes to pin 42 on the engine ECU.

I would not advise cutting it as it would put additional strain on the gearbox clutches, at the least the gear changes are likely to be rough, at worst it could damage the clutches if the gearbox is old and worn out. I plan to connect a small digital oscilloscope to that control line on mine so I can monitor WHEN the gearbox is commanding torque reduction to rule out the gearbox as the issue.

I think earthing of engine and transmission should be checked too. That is something that could explain when thing sometimes work.

Do you know where the earth points are for the engine and gearbox ?

One thing that occurs to me as well is the knock sensor has a special cable with extra shielding as its in a very "hostile" position yet produces a very low voltage high impedance signal, I wonder what the effect of a broken shield would be on the knock sensor cable ? It may be intermittently picking up interference from the ignition and other devices triggering erroneous knock related timing retard.

In most cases where my engine has felt down on power it has felt like retarded timing. Although its running much better lately, once again today after a lot of driving the low rpm performance has sagged quite noticeably, feeling a bit "lethargic" and unresponsive at low rpm, but after sitting and cooling for a couple of hours the performance is better again. It usually seems to be worst when warmed up.

Air in cooling system can cause very interesting issues also, because engine tempereature sensor is fitted so that it may not touch coolant at alla if there is air in system (causing sudden sputters and even may cause engine to die when thermostat open suddenly and there is burst of water onto sensor). So check that.

I definitely need to bleed the cooling system, although when I have monitored the coolant temperature via a Lexia I have never seen any evidence of the sensor reading incorrectly or erratically.

Tapping valves tell me when to change engine oil. On my engine, there is no tapping at all.

Mine has been silent since I put the additive in but I will be changing the oil soon.

Then there is this oil on spark plugs thing, but i think you already checked that.

Although mine does have a small leak in the rear camshaft bank at the right hand end which has allowed some oil into the square wells, no oil has ever got onto the spark plug boots or down into the plug towers.

As you may have read I did get bad carbon fouling on the insulator of the rear spark plugs but I think that was a combination of short trips and the wrong heat range spark plug.

Edit: one other thing that may be worth checking is the quality of the signal from the crank shaft sensor. Now that I have a small digital scope I might try to get a reading on this on the back of the ECU plug if I can get the cover off the plug. The only problem is we're moving house at the moment (twice!) so it could be a month or more before I get a chance to do any further testing on the car.