C5 - clicking with revs [solved]

[Ben82]

I'm struggling to find it, tried doing a video to attempt to help find it... But I cannot for the life of me see where it is, am I even looking in the right area?

Looking at the xantia one in the service docs it looks like it is in a different place.

[Ben82]

Found the following in the Cit Service Docs..

8. Function : Fuel vapour recycling (canister)
Engine stopped : The electrovalve is closed , The canister absorbs the fuel vapours coming from the tank.
The electrovalve, monitored by the injection ECU, allows the petrol vapours stored in the canister to be recycled.
Recycling of petrol vapour is authorised in the following conditions :
[*]Coolant temperature above 60°C
[*]Air temperature higher than 5°C
The quantity of petrol stored in the canister is determined by the ECU.
As soon as the canister has to be purged, the ECU causes the engine to operate temporarily on a homogeneous mixture.

I'm not entirely sure about the coolant temperature, but it happens when the gauge has barely reached off the blue area (I know the middle represents the optimal 80C (ish)). Maybe I'll try to do a test with the lexia hooked up to try to confirm it only happens once it's at least 60C.

[Mandrake]

Are you thinking that maybe the canister discharge solenoid is the clicking noise you hear ? When mine was clicking it was quite loud and clicked at about engine idling rate, and did stop clicking when I lifted the engine rpm above a certain point. Perhaps see if you can find the connector for it and disconnect it while your clicking noise is there ?

The Lexia should have an actuator test that will manually click the solenoid to confirm whether you have found the correct connector or not...

Not sure that I understand what they're saying when they say homogenous mixture...

[Ben82]

Are you thinking that maybe the canister discharge solenoid is the clicking noise you hear ? When mine was clicking it was quite loud and clicked at about engine idling rate, and did stop clicking when I lifted the engine rpm above a certain point. Perhaps see if you can find the connector for it and disconnect it while your clicking noise is there ?

The Lexia should have an actuator test that will manually click the solenoid to confirm whether you have found the correct connector or not...

Not sure that I understand what they're saying when they say homogenous mixture...

Hi Simon, Steve suggested it was a possibility that it was that making the noise, Jim gave it's proper name, so I went hunting. Problem is, look as I may, I cannot for the life of me find it under the bonnet (I've checked the diagram, and it's a different location on the xantia v6 - as far as I can tell anyway, the pipework goes in a different direction). Take a look here for the c5 diagram.

Going by my lack of knowledge, that to me appears like it should be somewhere in the area to the rear right of the engine (i.e. the correct area where the clicking is coming from). If I could find it then I could just stick my stethoscope on it to eliminate it, but alas it eludes me

[Ben82]

Hopefully I won't be jinxed saying this and it turning into a thread similar to Simon's Exhaust thread.

I'm (bearing in mind I'm not an expert so could be wrong) certain it's the Canister.

So I took the lexia out to the car to try to log the coolant temp etc, armed with my phone in dashcam style, I went for a drive with the lexia, I found some interesting things to record on the lexia. Take a look:

If you want to see the accompanying video footage to coincide with it then let me know and I'll send you a link in a PM for it

I think this confirms that it is indeed the canister, the issues I have is:
1) Does this mean it is faulty? or is there something else causing it to be overactive?
2) Where the hell is it?!

PS: it looks like the info found in the Cit Service docs is wrong, as it was -5 outside, I guess the graph is from -15C to 0C as i would expect the relative air temperature to get warmer? And the canister starts doing its thing before the coolant reachers 60C.

Thoughts please?

Ben

[Mandrake]

Hopefully I won't be jinxed saying this and it turning into a thread similar to Simon's Exhaust thread.

And you definitely don't want that.

I'm (bearing in mind I'm not an expert so could be wrong) certain it's the Canister.

So I took the lexia out to the car to try to log the coolant temp etc, armed with my phone in dashcam style, I went for a drive with the lexia, I found some interesting things to record on the lexia. Take a look:

canisterlogfull.PNG

If you want to see the accompanying video footage to coincide with it then let me know and I'll send you a link in a PM for it

I think this confirms that it is indeed the canister, the issues I have is:

I'm not sure that this confirms anything, unless you mean you could hear the noise at the times when the canister purge electrovalve was active ?

1) Does this mean it is faulty? or is there something else causing it to be overactive?

Really hard to be sure, I don't really know what the normal operation of the valve is, the documentation I have is a bit vague too. The way I understand it is that the purge valve is normally closed (canister isolated from the intake manifold) and the ECU somehow monitors how much fuel vapour has been absorbed from the fuel tank into the canister - where and how it monitors this percentage (canister electrovalve ecr %) is not explained.

When it gets over a certain percentage and the engine and driving conditions are right (usually NOT at idle for example) then it operates the purge valve to allow the collected petrol vapours to be fed into the intake manifold and harmlessly burnt in the engine instead of escaping into the atmosphere. The whole point of the system is to prevent stray fuel vapour escaping into the atmosphere and absorbing it and storing it until it can be burnt.

However how often should the valve open during driving ? I don't know. And when it does open should it just open continuously for a few seconds, or rapidly pulse open and closed ? Again, I don't know.

When I first looked at your graph of purge valve and ocr % it looked like it was working properly but then I realised that it is remaining on most of the time after 100 seconds, rather than off and just pulsing on now and then.

When I heard mine it was quite a surprise because it was doing it at idle for prolonged periods of time, it was clicking very rapidly - I'd say 4 times per second roughly, and I'd never heard it before under the same conditions, so I have no idea why it was doing it, unfortunately I didn't have a Lexia on it at the time.

Assuming that you do confirm its the clicking noise, I'm not sure where to go next in figuring out WHY it's clicking so much... is something causing the canister to absorb an unusually large amount of vapour for some reason ? Like a fuel line leak ? Is there a problem with the sensor that detects that the canister is full of petrol vapour and needs purging ?

It seems like it thinks that it needs purging nearly the whole time you're driving which doesn't seem right. Anyone else know a bit more about how the canister purge system should work, how often it should purge etc ? I've never tried to troubleshoot one before and don't know much about them.

2) Where the hell is it?!

I think your best bet to find it is set to the Lexia to activate the solenoid repeatedly while the engine is off, that way you only have one noise to listen to. Judging by under bonnet photos you're probably going to have to remove some of the plastic covers in the engine bay to get better access to it...

PS: it looks like the info found in the Cit Service docs is wrong, as it was -5 outside, I guess the graph is from -15C to 0C as i would expect the relative air temperature to get warmer?

No I don't think its backwards, I think your intake air was genuinely getting colder. Was the car parked inside a garage above outside ambient temperature before being driven ? The air intake temperature would have started at that indoor temperature as the inlet ducting had warmed to ambient temperature inside the garage (15 degrees ?) perhaps helped by residue engine warmth, but once you got outside and started driving the continuous flow of -5 degree air through the inlet ducting will have cooled it down from 15 to 5 degrees, as I see you didn't go over 30mph...

If you had kept driving a bit longer and driven a bit faster I think you'll find the reading would have started to go up again as the hot engine warmed the air intakes back up again, in fact I'm sure I can see the inlet temperature starting to rise again right at the very end...

And the canister starts doing its thing before the coolant reachers 60C.

Yes, that is a bit odd.

[Ben82]

HI Simon,
Thanks. Let's answer some of your questions (it may have actually have been helpful to see the video haha!)..
1) yes the clicking happens when the purge valve is open, I rev the engine at a stop near the end, which deactivates the purge valve (I could see it switch to inactive, and the clicking would stop briefly, it would then start again (instantly in this case) and the purge state would flick back to active.
2) I had left the car parked outside this time (we have some free spaces outside, I generally need to make 3-4 trips out on Fridays including to take my daughter to riding school, so if I can I leave the car out in one of those spaces).. In this instance it was deliberate also so the engine should have well and truly been cold when I tried this test. You could be semi-right though as you can see the coolant starts off at 20C, so maybe the temperature within the bay was still fairly warm It does look like it starts going up again. The clicking kinda started earlier than I thought it would, had it waited for another minute or so I probably would have gone on the motorway.

I have now since found this, check page 149 (footer ref, or 152 actual reader page) and this (Page 38). This tells me a few (hopefully) helpful things:
1)It confirms it's under the front LH wing (so I'm in the right area), I guess I could remove the wheel arch cover, and see if I can see it from that angle, now I know it's that, I don't really need to find the clicking, just need to find the canister/electrovalve.
2) "Electrovalve normally closed", mine appears to be normally open.
3) "when decelerating, the canister is not bled in order to limit emissions of unburned hydrocarbons and to avoid damaging the catalytic converter." going by the graph once active this seems to be the only time it closes.

Speculations:
1) I think you've debunked this one already, but might as well throw it in... could it be fuel starvation? e.g the filter is not letting enough fuel through, so it's using the vapour to make up for it? This seems unlikely as it's not related to when the system needs fuel.
2) The carbon filter has reached its limit, I guess this is most likely, as it seems like it's trying to purge it continuously (unless prevented from doing so as with point 3 above).

[Ben82]

Well another update.... took her out for another spin tonight (including motorway), and we get the following graph:

I thought I'd sacrifice Vehicle speed this time, for an O2 sensor. My theory was, maybe rich/lean was a contributing factor. However I don't think it is (and unfortunately I think a downstream sensor without context is a bit useless for this - we are afterall not testing cat efficiency).

If you had kept driving a bit longer and driven a bit faster I think you'll find the reading would have started to go up again as the hot engine warmed the air intakes back up again

This time round, the faster I went the colder it got... only started to warn up again once I had slowed down/stopped. (Makes sense though, -9C air rushing in at 110km/h isn't going to have much of a chance to warm up by the engine).

You can see that idling at the end, it does after a while turn off, and turns on again without being prompted to. There's also 2 minutes of unexplained "off time". The OCR looks rather off from about half way through too.

Actuator test also makes it click a lot! But it's supposed to.

I also wonder that since my Canister completely violates the rules of being active, I wonder whether it's been configured differently for being over here? otherwise it's likely that with the 5C air temp requirement, that it probably wouldn't be able to work for 1/4-1/2 of the year!

I am currently doing the semi-impossible task of looking at SEDRE to see if I can find the electrovalve and see whether there is anything that would suggest it tells the ECU when the canister needs purging.

[Ben82]

Well what is this?

I wonder whether the arrow means it's behind the firewall? Seems a bit silly if it was, since it contains fuel vapor! But it is french lol I guess I can follow the wiring going off in that direction.

Looks like it maybe under the plastic cover of the Suspension sphere.

How do you get the push clips off? I seem to break any of the ones I touch. Logically I lift up the centre bit, and then try pulling it out, but can always guarantee it still has grip, and I end up breaking some part of it Not sucecssfully got one off the car yet! I dunno whether they've turned brittle.

[myglaren]

I usually extract the centre pin completely. Still manage to break the odd one. Not many left now.
Bought a big bag of them at the northern rally a couple of years ago but the are always the wrong size for replacing the ones I break or are missing.

[Ben82]

I usually extract the centre pin completely. Still manage to break the odd one. Not many left now.
Bought a big bag of them at the northern rally a couple of years ago but the are always the wrong size for replacing the ones I break or are missing.

Thanks Steve, I thought that might be the case, but the one I tried with it, part of it snapped inside the other part, so kinda assumed it wasn't supposed to come out. Will give it a try, may have to buy some myself to replace the broken ones. (until they break again! )

[Ben82]

Success (In locating it at least). Under the cover for the suspension sphere. So Simon you were right in that it was under one of the plastic covers.

It was touching the cable that goes to the brake fluid master cylinder. I've read online that these things can resonate their noise if they're touching something, so have moved it away from the cable. Will see later if this has deadened the noise, if not it seems like the part is about £20, and looks like it should be rather easy to replace.

[Mandrake]

Excellent Have you tried disconnecting the plug to see if the clicking you've been hunting all this time definitely goes away ? It shouldn't do any harm to temporarily disable for a test drive as its a non essential component that is only there for minimising fuel vapour emissions into the atmosphere.

As to whether its just unusually noisy because it was up against something, or whether there is something that was causing it to operate when it shouldn't, I don't know.

[Ben82]

Not yet Simon, I'll try to give it a shot later when we go out if moving it hasn't done anything.

[Ben82]

Used my stethoscope to confirm its the thing that is clicking (also used my finger - you can feel it clicking). was -11C outside and had just gone skiing (Well that if you can call a lot of falling over on a slope with skis on: "skiing" ) so didn't want to hang around out in the cold for too long.

But of course moving it didn't really help, so time to hunt a replacement and see if that fixes it.