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

[addo]

Malc - I'm not talking mushroom plug but the old school sticky strips. 4WD stores sell them as they're a must-have for minor punctures on the go.

BTW that spare - I have a picture of what happens next (BIG blowout) but can't post it as the friend pictured with her handiwork, may consider her attire indecorous...

[lexi]

Take the tyre back forthwith. Also tell them that since they have had the vehicle it has developed a misfire and they must fix it

[Mandrake]

Haha nice one Alex, only trouble is I only left the wheel with them last time not the car, so I don't think that one would fly.

Addo: I agree, as soon as I saw the crack I was very wary of it. I only drove a couple of miles with it on and only at 30mph and below. I wouldn't drive on it at motorway speeds which is why my choice of tire repairers was limited to the few that I can get to without traversing a motorway...

Looks like I'll need to replace the spare next month when I have money again... I'm thinking of seeing what Costco can do as the other half is a member now. Not a michelin, just a cheap but full size budget tire. They shouldn't have any trouble balancing the spare as its not centre-less.

I've booked the car in to have the wheel re-balanced on Monday. Fingers crossed they get it right this time!

[myglaren]

Malc - I'm not talking mushroom plug but the old school sticky strips. 4WD stores sell them as they're a must-have for minor punctures on the go.

BTW that spare - I have a picture of what happens next (BIG blowout) but can't post it as the friend pictured with her handiwork, may consider her attire indecorous...

Photoshop some clothes onto her

[DickieG]

Looks like I'll need to replace the spare next month when I have money again... I'm thinking of seeing what Costco can do as the other half is a member now. Not a michelin, just a cheap but full size budget tire.

Costco only sell Michelin and Continental tyres so not a lot of use if you're looking for a cheapie Nankang Ping Pong.

[Mandrake]

Hmm are you sure thats the same for all costco's ? I know they do michelins but I though I saw a few other brands listed as well when I was there. Do you know if they can balance centre less rims ? Might be a good choice for two new michelins for the rear when they're needed if they can...

[DickieG]

Hmm are you sure thats the same for all costco's ? I know they do michelins but I though I saw a few other brands listed as well when I was there. Do you know if they can balance centre less rims ?

That's all I've seen at Reading and the HQ at Watford, not sure about centre less rims etc.

[CitroJim]

Ours also does BF Goodrich as a 'budget' choice... Not as 'budget' as some but a bloody good tyre in my opinion. I have a pair on the front of my V6 and I'm happy with them. Also used them on the old V6 and on the 2.1TD with happy results..

[citronut]

BTW that spare - I have a picture of what happens next (BIG blowout) but can't post it as the friend pictured with her handiwork, may consider her attire indecorous...

Adam now you have told us you have got to show us

[Mandrake]

Hi Guys,

Just down on the car running a few tests in this beautiful weather and one of the first things I checked was some of the Lexia actuator tests on the engine... And noticed that the spark test for cylinders 1,5 sounds very muted. The other two give a loud tick that sound about the same as each other coming from under the top cover (still in place at the moment) while 1,5 sounds quite quiet and muted.

Has anyone done the Lexia spark firing test before on their V6 and if so could you confirm that all three should click at about the same volume ? I can't see any reason why they would sound so drastically different other than a fault.

Also the gearbox is reporting an intermittent engine speed signal problem (27 occurrences logged) which it hasn't shown since the first time I put the Lexia on the car months ago... I assume it means the signal it gets from the crank sensor via the engine ECU ?

Further, the Hydractive ECU is reporting an intermittent throttle pedal adjustment fault code as well, which I have not seen before... I'll post the exact fault codes in more detail this evening.

Wasn't expecting to find this many new faults logged...

[Mandrake]

BTW when doing the spark test with the Lexia you sometimes need to disconnect the FRONT relay in the ECU box otherwise it's clicking during the test obscure the actual sound of the spark. Why it sometimes clicks the relay at the same time during the ignition test I do not know!

[CitroJim]

Simon, here's something to ponder. I now have two V6s to my name again.. Both very different in character. the XM V6 is a lot perkier than the S2 Xantia V6...

And yet they're identical engines...

Why? Both run fine and beautifully and both return about 35mpg on the Somerset run and both change gear in error in exactly the same places on the journey.

Discuss...

[Mandrake]

Interesting Jim, considering that I'm sure the XM is significantly heavier ?

Describe perkier - just more power overall, or is it more specific than that, like better pickup low down or better power at the top end ?

BTW I'm composing a mega post to cover what I've tested and discovered today - its probably too big to fit in one post (and has more than 3 image attachments) so I'm writing it in word first to copy and paste! Suffice to say I've been a busy boy today...

[Mandrake]

Today has been a busy day out on the car, a lot of things have been tested, some things have been discovered, but as often is the case more questions have been raised than answered, so I present findings here rather than conclusions per-se and hope that you all have some thoughts and feedback on what I’ve found.

This will be long so I’ll break it up into separate posts, this one covering fault codes.

The first thing I did was put the Lexia on the car for the first time in a while and was surprised by quite a few fault codes having been logged. In particular:

The Hydractive ECU logged a fault that I’ve never seen before:

“Intermittent fault - Incorrect accelerator pedal adjustment”

Anyone know what apart from the obvious this means? Is there an adjustment on the accelerator pedal somewhere separate to the slack adjustment on the cable at the throttle body? Since the Hydractive throttle sensor is a pot on the pedal arm itself I can’t see how it would know about any adjustment error in the normal throttle cable adjustment under the bonnet…

I checked the live sensor data while depressing the pedal and got the following voltage readings:

Throttle closed – 1.23v, full throttle – 3.59v, and I noticed that if I lift the pedal with my foot it drops to 0.74v. There does seem to be a bit of slack in the pedal such that I can lift it higher than its resting no throttle position. Is this perhaps what the ECU has detected and is complaining about ?

Fault code number two was from the gearbox, but appears to be the gearbox complaining about incorrect engine speed data from the engine. This same fault was logged the first time I read the car with my Lexia back around October, but has not returned until now. Here’s the screenshot:

I assume 29 is the number of times the fault has been detected? Can someone confirm that it is actually the speed data from the engine ECU it is complaining about and not one of the gearboxes own sensors?

The way I understand it the gearbox gets engine RPM (equal to torque converter input speed) from the engine ECU over a serial bus, and then internally measures the torque converter output speed and final drive input speed with its own two sensors.

If this is a faulty signal from the engine ECU could it mean problems with the crank sensor on the engine? (“Engine speed sensor” I presume is the crank sensor) On the other hand if this were the case why didn’t the engine ECU log any related fault? Perhaps a communication problem between the two ECU’s?

A little bit puzzled by the appearance of both these fault codes. On to spark testing in the next post.

[Mandrake]

I’m not sure why I tried this to be honest but I ran a spark test using the Lexia where it fires individual coils about once per second with the engine not running. For some reason it sometimes clicks the front (injection?) relay in the engine ECU box so you have to disconnect that to hear the spark clearly.

What I noticed is that the sparks from Cylinders 2 and 3 were quite a loud and distinct tick, while Cylinder 1 was very quiet and muted so that I could only just hear it. To check that the coil is actually firing I disconnected the plug leads to the rear bank and replaced them with alligator clip leads forming 10mm spark gaps to earth – all three generated a nice fat spark easily exceeding 10mm and all were the same.

Last week I also tried my in-line (neon) spark testers as seen below, which showed (at least visually) that there was no problem with the spark as it leaves the top side of the coil:

Not as good as putting the ignition on a proper engine scope of course but I couldn’t see any missed sparks even when blipping the throttle.

Being a wasted spark system that shows that the coils are almost certainly ok however testing on the top side does not prove that the spark going to the front plugs isn’t just jumping to ground through bad insulation etc, so I decided to pull out the coil pack and inspect the rubber boots that go to the plugs as well as the plugs.

The rubber boots looked fine but I still had the old pair belonging to the previous rear cartridge so I tried fitting those – no change, the number 1 cylinder spark still sounded weak. I also still have the old coil pack so I swapped that too – no change to cylinder 1, the other two got slightly weaker sounding if anything, but no real significant change…

So I then decided to check the plugs in case one was cracked and tracking. What I found is that spark plug 1 seemed ok but both two and three seem to be fouled with carbon on only one side of the electrode centre insulator. Here are plugs 1, 2, 3 (right to left looking at the engine) in order:

(continued)