C5 - clicking with revs [solved]

[Ben82]

Hi Chaps,

Right I have managed to find the area where the ticking is coming from (without a second person around ), and I can say the following:

1) Aux belt is highly unlikely to be the source.
2) I don't think the area it is coming from is the tappets (but I could be wrong)

The area from the bonnet where the sound is most prominent is coming from here:

(excuse the poor camera quality!)

Moving my head over the top back of the engine it is definitely quieter, even took off the main engine cover, no difference in volume.

So seems to be something down there to the right of the engine making the noise.

Would the tappets be heard more from down there or could it be something else?

Thanks

Ben

[Mandrake]

Won't be tappets then, tappets are at the top of the engine where the camshafts are - one set towards the front (in line with the oil filler cap) and the other set towards the back under the inlet manifold.

Can't think of anything that would click at engine rpm from that area... Could you try to make another recording of the sound with the recorder in the area where it's noisiest ?

[CitroJim]

Ben, I can't even identify that area of the engine from the picture. Sorry, Can you describe where it is please?

[Ben82]

Ben, I can't even identify that area of the engine from the picture. Sorry, Can you describe where it is please?

Hi Jim,

Just down the right of the engine, to the right is the "electronics" cover which is above the battery. The beginning of this video should make it easier to see (albeit being a Pug): , BTW it seems from that video he is able to rev the engine from the engine compartment? anyone know how to do this? (would be extremely handy for this issue if possible)

Simon, I tried for nearly half hour this morning to be able to hear it properly from the engine compartment, but no luck, when I got back the ticking was either not happening, or was very quiet, so could hardly hear it in the engine compartment, I'll try again later, hopefully it'll do it louder again then (Well I would really like for it to just disappear, but I don't think that's going to happen).

[Ben82]

Righto, Success!!

This starts off a bit dark, then I remember to turn on the torch I had put in my pocket
https://www.dropbox.com/s/sk9ha2l876tn9 ... .34.28.mov" onclick="window.open(this.href);return false;
As you can hear when I take it across the top of the engine briefly around 0:15, it goes quieter.


And for reference, this is what it sounds like when it's not making the noise (I had to rev the car a few times to get it to stop tonight!!, again forgot the torch, but same area anyway!):
https://www.dropbox.com/s/wkcjdhh2yuxep ... .59.37.mov" onclick="window.open(this.href);return false;

Any ideas?

BTW: it was taken on an iPhone, I used the windscreen mount to hold it so I could lower it down etc, and to ensure I never covered the microphone on the bottom of it

[Mandrake]

Fascinating noise, but I'm afraid I don't have a clue what it could be.

Hopefully someone else has an idea. It seems almost as if its not coming from the engine proper but from the throttle body area, but what there could click...

[dnsey]

That sounds rather like HT arcing to me.
I'm not familiar with the V6 - does it have coil packs or more traditional coil/distributor?M

[Ben82]

That sounds rather like HT arcing to me.
I'm not familiar with the V6 - does it have coil packs or more traditional coil/distributor?M

Thanks Apparently: 6 individual coil packs, no distributor.

You know, when listening to it again after sending it to my dad, I was thinking it does sound a bit like electrical clicking. Which of course could be linked to revs because more revs = more sparking of the plugs. Wasn't until I saw your post that I had the "ahhh" moment.
Dad reckons best way to test this is (preferably in daylight) follow the cables from the spark plugs back to where they go and make sure they're connected properly, then if it's still happening after that then check during complete darkness and look for sparks, any other tips? (Daylight is in short supply here at the moment)


Edit: This sounds familiar, I think we're onto a winner

Edit2: It's all falling into place: the other mechanic said about getting a small shock from the engine, this would explain it.

[Mandrake]

Sounds possible, however do you notice any loss of power when the noise is there ?

A noise that loud from an HT lead arcing to earth would cause a serious misfire and a very obvious loss of power.

I've just recently found and fixed a damaged arcing spark plug lead on my V6 - it was misfiring quite badly due to a puncture in the cable allowing spark to jump about 10mm to earth. There was a large loss of power, I'd say at least 25%, and there was no audible or visible spark, definitely nothing like the noise you're hearing...

[Ben82]

hmm, good question, and I'm going to go with No, not really. However would I notice? considering we're in snowy weather here, i'm not accelerating quickly, and often it's happening when i'm keeping a level speed or adjusting slightly.
Is it also possible if it's at the other end of the cable, that it's arcing onto the cable itself (without losing insulation) so it's still providing the power (because the quickest way to ground is down the cable)?

[CitroJim]

That noise almost sounds like a relay clicking. At least it's nothing deeply mechanical... The only things that spins in that area when idling and in neutral is the torque converter and bits of the gearbox and it sounds too clear and high-pitched to be that.

Good call on an HT arc. Is it worse when the weather is damp at all?

Final thing it might be if all else checks good is the idle control valve. A stethoscope will determine if it is the culprit.

[Ben82]

Jim, unfortunately damp is fairly consistent here at the moment, but if I leave the car outside rather than in the garage, it does seem worse, but I don't do that often (since the free spaces are generally in use), and given the semi random occurrence of when and how badly it happens, it's a tough one to call.

Had a good look around this morning to look out for a spark, couldn't see one, I think I'm going to need to take the fuse cover off, see I can see anything with that removed. Also probably worth me getting a stethoscope anyway for this issue, should help locate exactly where it is.... Especially if it's under insulation or if something is blocking my view etc.

Searched the citroen service docs for the idle control valve to find out where it is and what it looks like, but no luck, any ideas?

[Mandrake]

The idle control valve is typically a cylinder shape, it should be mounted on the side of the throttle body, it provides an air bypass around the closed butterfly to regulate the idle speed. On the earlier V6 it has its own hose from the air filter box, but I'm not sure if yours is like that. Look for a hose going from the air filter box to a cylinder mounted on the throttle body (which will also have an electrical connector) and that should be it.

If you unplug the electrical connector the idle speed should increase or drop. (It may stall if cold) This will generate a fault code which you'll want to clear afterwards with the Lexia. Don't confuse the connector for the nearby throttle position sensor which will be in line with the pivot point of the butterfly.

The Lexia can read the degree of opening of the valve, it should be in parameters measurement and called something like "Idle OCR valve" or similar, it will be a percentage that should be around 50% with the key on but the engine stopped, and between 30-40% when the engine is idling. Adding load to the engine such as turning on the A/C or putting it into drive should cause the percentage reading to go up a few points as the valve opens slightly more to maintain the desired idle speed.

I can't really see how the idle control valve could be making that noise, but unplugging it for a few seconds would certainly prove it one way or the other...

[Ben82]

Thanks Simon, think the Pug equivalent comes to the rescue again, with this. (Page 4, part H "Throttle Stepper Motor").

So get the car warm and ticking first then pry the clip away and pull the connector off, wait a few moments (see if the clicking stops, if it's still there and increases/decreases with the revs, then we know it's not that), and connect it back up (if the clicking did stop, see if it has returned etc).

Only issue is, with the random nature of the ticking occurring, and it being able to appear/disappear with changes in the revs, could find that disconnecting it, offsets the revs enough to make it inaudible, and then reconnecting it bring it back to ticking again. Giving a false sense of it being that. Will give it a try anyway, since it will help try to eliminate another thing

[dnsey]

Arcing to ground would certainly be likely to result in a misfire, but if the arc were across a gap between a plug terminal and coil secondary, for instance, it wouldn't necessarily affect running, although it wil stress the coil insulation.
It's worth running the engine in the dark and looking for visible tracking or arcing, but it's more likely to be hidden under the coilpacks, which I believe are a bit of a pain to remove in this case.
Try using a small AM radio in a similar manner to a metal detector. There's bound to be all sorts of 'hash' near the engine, but you may find a louder audible click in the immediate proximity of a faulty ignition component.