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

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

Post by Mandrake »

Ben82 wrote:Simon, on the 4000rpm thing:
http://www.406coupeclub.org/Coupe_Engines.asp wrote: 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
Just stumbled across some power and torque graphs for the ES9J4 as well as some of the other engines used in the XM:

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

Yes there is definately a bump in the torque at 4000rpm, although not huge. Impressive how flat the overall torque curve is over such a wide range though, compared to all the other engines. :)

Strange thing is one of the 3rd party dyno readings further down the page shows a dip at 4000 not a peak...but later ECU versions could potentially have slightly different mapping to smooth out that peak, or it could be just unit to unit variations...
Last edited by Mandrake on 24 Apr 2013, 20:59, edited 2 times in total.
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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

RichardW wrote:We've got a 'driod phone. I've also got cover for driving other cars on my insurance if you need a pilot 8-)
I'm pretty sure a standard OBD-II reader like torque pro won't talk to a 1998 Bosch MP7.0 ECU, I'm yet to find a single confirmation that it would work so I'm not sure that its worth me buying the Bluetooth adaptor on the very slim chance that it might work...

I will take you up on your piloting offer next time I'm over though so that I can monitor the Lexia in real time while you drive. :)
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 Citroëns is that the stats tend to fail open after 90 - 100k. Oh, look, what is yours at ??? =D>
Indeed, around 100k seems to be where everything falls apart... #-o its up to 103,500 now, I think it was on about 99,500 when I bought it.
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!
If I could get a good look at the timing "torque reduction" figure while the car is being driven I think we could confirm it... Only two things should cause the timing to be retarded a lot - knock sensor activity, and a command from the gearbox during gear changes...(which only lasts about a second)

I've seen randomly fluctuating timing retard figures in excess of 20 degrees during normal driving a few weeks ago, although it was hard to tell exactly what driving conditions were triggering how much retard as I was driving and the numbers were just being read out to me... But there shouldn't really be any additional retard unless you floor it with low octane petrol unless I misunderstand how it works...

I'm thinking of trying some 97 petrol at the next fill up to see if it makes any difference. Who here runs what octane in their V6 ?
Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

Indeed, around 100k seems to be where everything falls apart... #-o its up to 103,500 now, I think it was on about 99,500 when I bought it.
That's why mine went approaching 130,000, engine was still great but all the rubber and plastic bits were beginning to decompose and I was spending more time repairing it than driving it. When the aircon pump blew its guts that was the final straw. Still miss it though :(
I'm thinking of trying some 97 petrol at the next fill up to see if it makes any difference. Who here runs what octane in their V6 ?
The difference wont be immediate, it takes time for the ECU to figure it out, but you don't get the full 194bhp on standard fuel. I always ran mine on Shell V Power when possible.
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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Stempy wrote:
I'm thinking of trying some 97 petrol at the next fill up to see if it makes any difference. Who here runs what octane in their V6 ?
The difference wont be immediate, it takes time for the ECU to figure it out, but you don't get the full 194bhp on standard fuel. I always ran mine on Shell V Power when possible.
I might give V-Power a try next time I fill up... if anything it will help me isolate whether the timing is retarding from genuine knocking from lower octane fuel or whether its picking up other mechanical noise causing spurious retarding... if it still shows timing retard on 99 fuel I'll know its not knocking from low octane fuel causing it! Of high octane fuels I haven't tried V-Power before, only BP Ultimate 97 which I think I used for a couple of months...

BTW while reading about V-Power it looks like V-Power is in the process of being replaced by "V-Power Nitro +", same 99 RON but a different additive/detergent package... :roll: Does anyone know what the maximum RON the ES9J4 is tuned to take advantage of is ? I seem to recall its 98, but I don't remember where I read that...(EDIT: found several sources that quote "optimised for 98 RON")
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Mandrake
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Of course for those of us wanting more power from the ES9J4 there is always this:

http://www.dp-engineering.nl/projects/p ... turbo.html" onclick="window.open(this.href);return false;

Very impressed by this, although where did they put the battery... :-D
Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

...or even this

http://www.ebay.co.uk/itm/Citroen-C2-V6 ... 3381a71ec8" onclick="window.open(this.href);return false;
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Ben82
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Ben82 »

Mandrake wrote:Of course for those of us wanting more power from the ES9J4 there is always this:

http://www.dp-engineering.nl/projects/p ... turbo.html" onclick="window.open(this.href);return false;

Very impressed by this, although where did they put the battery... :-D
Seen that before, and yeah it is very impressive :D... I didn't notice before about the lack of place for the battery lol

PS: those dyno graphs look pretty interesting.

@Stempy... how on earth did they manage to fit the ES9J4S under the hood of a C2?!! That's very very impressive.
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CitroJim
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by CitroJim »

Ben82 wrote: how on earth did they manage to fit the ES9J4S under the hood of a C2?!! That's very very impressive.
Impressive? certainly. Sensible? Debatable...

The battery goes in the boot...
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Did a quick top hose test of the thermostat tonight - the conclusion is that the 'stat is not stuck open as the top hose stayed completely cold for well over 10 minutes of idling, and only started to warm up once the gauge indicated around 75-80 degrees. Possibly opening a bit too low but on the other hand my temperature gauge is a bit hit and miss - it usually reads lower than the Lexia and sometimes intermittently fluctuates while driving, so I really needed to check it with the Lexia measuring the temperature but I was too lazy... next time...

So, not stuck open but not necessarily opening at the correct temperature. Also it took something like 12 minutes of running, 10 minutes idling and maybe 2 minutes at 2000 rpm to try to hurry it up before it got hot enough to open the thermostat... does that seem unusually slow to anyone ? it was a good 7-8 minutes before the temperature gauge even started lifting off the stop...

Not sure what's going on with my dashboard temperature gauge - today when I drove up a steep hill the reading dropped by nearly 20 degrees then came right again as soon as I levelled out at the top. Sometimes even accelerating while going up an incline - causing the car to tilt a bit further back on its haunches is enough to make the reading drop then rise again when I let off the throttle allowing the car to tip forward a bit.

Air bubbles in the coolant ? Dodgy wires to the sensor ? The Lexia temperature reading always seems stable and accurate...

Is it worth me trying to bleed the coolant, and will it be doing the system any harm with me running with the pressure cap loose due to the split expansion tank ? If I leave the cap tight it blows out excess coolant through the seam, if I leave it loose I don't lose any coolant but of course its running unpressurised...
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CitroJim
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by CitroJim »

Sounds entirely normal to me Simon. The engine has a lot of coolant in circulation and some very expansive water jackets - much bigger than you'd expect really when compared to a four pot engine.

So, all that water does take some time to heat up.

I note oddities on the temperature gauge too and in fact have seen precisely what yours shows.

You have to remember that effectively the temperature gauge sender is in the bottom hose (in fact it's screwed into the base of the rear bank) so what it reads is more the radiator return temperature rather than the hot flow as is read in most engines. The green coolant temperature sensor is in the top hose effectively so is reading the hot flow and thus the hottest coolant so never try to compare and contrast the reading given by the gauge - with is typically Citroen and is better for predicting earthquakes than accurately reading temperature - and what the CTS is reading via the Lexia.

I think you can stop worrying about coolant issues :-D Do bleed though. It never hurts but in my experience the engine is pretty good for self-bleeding once initially correctly bled.

Bleeders are situated on the top of the rad, the top hose casting and thermostat housing, the latter two being brass Allen screws. Both very easy tom get to once the obligatory air-box is removed :)
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Interesting day today, sort of... :?

Yesterday I put some wynns hydraulic tappet additive in, did about 30 miles yesterday then on startup today the tappets were completely quiet at least for a few minutes, although a couple were a bit noisy again after a few minutes.

The car was performing fairly nicely yesterday and today. Then I filled up with Shell V-Power, left the battery off for 15 minutes to reset the ECU (for the higher octane fuel) and we set off on a drive up past Loch Lomond, what turned out to be around 120 mile round trip...

I'd say the first 40 miles or so the car was performing quite sprightly, nice and responsive to the throttle, plenty of power, good on overtaking, easy kick down to lower gears, no throttle lag etc then the performance slowly started to fade and lose its edge, by the time we got to our destination at the 60 mile mark it was starting to feel quite sluggish with the infamous "rubber throttle" characteristic, reluctance to kick down, and just no real zip, almost to the point where it was labouring at low rpm again.

We then stopped for about half an hour then set off home again - on the 60 miles back home the performance remained the same, no better or worse than the end of the first leg of the journey - flat and unresponsive, rubber throttle, labouring at low rpm, unwillingness to kick down etc.

As far as I could tell the engine wasn't misfiring, but it DID feel like the timing was severely retarded... occasionally kicking it down to 3rd at 60mph would be zippy and responsive as it should be then just a couple of minutes later the same kick down would result in very flat performance .

I'm almost certain its ignition timing advance/retard related but I don't know what's causing it...and why it can take 40 miles of driving before the performance starts going down the toilet...I know the knock sensor can retard the timing and I know the gearbox can retard the timing which it does during gear changes... but I wonder if the gearbox also commands the engine to retard the timing (to reduce engine torque) if its overheating or detects excessive slip in the torque converter lockup clutch ? I can't see any real way to confirm any particular theory as I have insufficient documentation of the inner workings of both ECU's and insufficient test equipment to determine it empirically. (Monitoring the data lines between the two ECU's etc)

This "drives fine at first but gets more and more sluggish during the journey" characteristic has been a hallmark of whatever is going on these last few months... it rarely ever gets better during a journey apart from random variations, the trend is always from better to worse the more you drive in a given journey...perhaps engine / gearbox / engine bay temperature is a factor...

Apart from the mystery loss of power the car ran beautifully, the ride and handling was good, I didn't lose any LHM (looks like the pump repair was successful) the exhaust didn't fall off, and the weather was lovely too. :) It's just a shame that it started off running so well and was back to its old tricks by the end...chances are I'll start it up tomorrow and it will be running well again! (for a while)
Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

From what I can gather the gearbox ECU will tell the engine ECU to reduce performance if the gearbox oil overheats, but don't quote me on it. Random faults like this are often down to electrical gremlins which are usually a pig to trace. I would imaging a gearbox overheat condition would register a code in the ECU which could be read on a Lexia, but then again I'm not an expert. The gearbox ECU does have several modes which it will flip to depending on driving style so may not always react in the same way. Mine used to be permantly in old man mode, i.e. get into top as soon as possible and stay there. If you are feeling let down on the performance then there's always that little button marked 'S' :-)
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Mandrake »

Stempy wrote:From what I can gather the gearbox ECU will tell the engine ECU to reduce performance if the gearbox oil overheats, but don't quote me on it. Random faults like this are often down to electrical gremlins which are usually a pig to trace. I would imaging a gearbox overheat condition would register a code in the ECU which could be read on a Lexia, but then again I'm not an expert. The gearbox ECU does have several modes which it will flip to depending on driving style so may not always react in the same way. Mine used to be permantly in old man mode, i.e. get into top as soon as possible and stay there. If you are feeling let down on the performance then there's always that little button marked 'S' :-)
Problem is when the car is really sluggish as it was on the way home today, even in sport mode its quite flat in performance. Obviously sport mode helps as it gets the revs up and keeps it out of "old man" gearshift mode, but its not just the gear selection that's the problem...

Mine also frequently ends up in "old man mode" where it shifts up early and stays there... I've found that it's not so much wider throttle openings that train it to stay out of old man mode, but how quickly you move the throttle. So if you drive smoothly and gradually open the throttle wide it might not change down and will stay in that mode however if you open the throttle quickly to the same percentage it will both kick down and switch to a more sporty mapping... personally I'd like to disable SK1 (old man mode) or write the same values as SK2 into SK1 to neuter it, but I can't see any way to do that without serious and risky firmware hacking... :lol:

Regarding the gearbox oil temperature, according to the training manual it does have two mappings that try to protect against the oil overheating, however they're only triggered at 118 and 120 degrees, which I don't believe mine is reaching. They trigger the gearbox to hold a lower gear more to keep the engine revs up to circulate the gearbox oil faster, and also eliminate the limited slip mode (using full lock up instead) to reduce heat generation in the converter. Above 125 degrees the full slip "open" mode is also disabled in most conditions.

Funny thing is even though I've never seen over 105 degrees reported on the Lexia during fast country driving, when misbehaving it does seem to severely limit the torque converter slip keeping it locked up most of the time. Normally when you accelerate you get a "half change down" when you kick down the throttle a bit particularly in 4th at 60mph with about half throttle... this is actually the torque converter unlocking which boosts the revs about 500rpm and gives torque multiplication and a nice extra boost in acceleration at the expense of worse fuel consumption... if you use even more throttle you get an actual gear change down to 3rd.

When misbehaving this "half change" doesn't happen, the torque converter stays fully locked up until you press it far enough to trigger a change down to 3rd...(at which point the converter is still locked)

Regarding whether the gearbox has control over the engine power output for reasons other than gear change torque reduction, the answer on studying the documentation again seems to be yes. On page 127 of the manual the table shows that "transmission oil temperature" is one of the inputs that affects "Torque reduction".

So if the gearbox thinks its overheating it can instruct the engine to reduce torque by retarding timing... I wonder if this is the source of general lethargic performance when well and truly warmed up after half an hour or more of motorway driving ? I haven't actually check the oil temp in these conditions, and it would take a long time (hours) for the oil to cool down once the gearbox was really piping hot.

Since the heat exchanger cools the gearbox oil via the engine coolant, could a thermostat that is running 10 degrees hotter than it should be be enough to push the gearbox oil temp to the point where the gearbox starts taking protective measures like reducing engine torque ? According to the Lexia my coolant temperature reaches as high as 98 degrees before the fans start dragging it down again, perhaps that's about 10 degrees too hot ? What's the correct 'stat temperature for this engine ? (Perhaps a new 'stat isn't such a bad idea)

Another interesting quote from the manual that I'd somehow missed before:
C - AUTOMATIC TRANSMISSION PROTECTION At very low vehicle speeds (Vveh < 5km/h approximately) or when there is a fault on the vehicle speed sensor line, if P/N is changed to D or 1st or 2nd or 3rd or R, a timer f (T°coolant) is triggered. During this timer, if the driver accelerates and if N > limit f (T°coolant) or TB > limit f (N, T°coolant), the ECU cuts off the injection so as to cause a large drop in torque in order to protect the transmission. Injection is restarted when the engine speed gradient reaches a limit f (T°eng). Injection picks up progressively until it reaches Ticalculated. The increment is of the type Ti calculated x Ktake-up where Ktake-up depends on the number of ignitions which occurred since the injection was cut off which represents the time for which the fuel was cut off. The table which Ktake-up comes from is specific to the "Automatic transmission protection" function. In addition, the optimum advance is applied from when injection is restarted to when Ti calculated is reached
Although it looks like this would only be used in case of a road speed sensor failure this is saying that the gearbox even has the power to command the engine to shut down or severely limit the injector pulse times, in addition to retarding timing... although its not clear how it might signal this.

Looking at the waveforms on page 167 on the torque reduction line from the gearbox to engine it looks fairly simple - high voltage (5v ?) is normal operation, low voltage is retarded timing commanded during gear change. If I can somehow tap into this line (not easy when both ECU's plugs can't be back-probed) and run the signal into the cabin I could potentially monitor that voltage while driving thus have a heads up display of what the gearbox is commanding in regards to torque reduction request. That could be very enlightening... :)
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CitroJim
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by CitroJim »

Simon, just one question. I know you have added a can of snake oil to the oil but have you actually changed the oil and filter yet?

If you haven't then do as soon as possible and then report back :wink:
Stempy
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Re: Xantia V6 broken exhaust (update: and rough low rpm runn

Post by Stempy »

Also have you checked the oil level in the geabox? If this is wrong I know from experience that it can cause all sorts of funny behavior.