P0340 code after Head gasket replacement

[brianmoooore]

You won't get the accuracy required without a dial gauge. The movement of the piston a few degrees either side of TDC is extremely small, and you need to establish exactly where TDC is.
Cylinder #1 is usually, with the odd exception, the cylinder nearest the crank pulley, but, as you say, the one the other end is usually its twin.

 

[Mechanic-al]

You won't get the accuracy required without a dial gauge. The movement of the piston a few degrees either side of TDC is extremely small, and you need to establish exactly where TDC is.
Cylinder #1 is usually, with the odd exception, the cylinder nearest the crank pulley, but, as you say, the one the other end is usually its twin.

Noted and understood.
What concerns me is that if I do find the crank marking doesn't match with TDC, but the manual says it should, something is wrong but it must've come from the factory like that. And then how was I ever expected to get the job done as per the manual ?
Does this kind of thing happen often?
As an amateur, I'm sure you understand my anxiety.

 

[brianmoooore]

Zooming in on the crank sprocket in your diagram of the chain and tensioners, it looks like its located by a woodruff key. Extremely unusual, but these can wear and partially shear, which would throw the cam/crank phasing out.
The fact remains that there is a problem that the ECU is unhappy with. Have you tried any owner's forums online? Sometimes it appens that what appears to be a very obscure fault is well known amongst those familiar with that model.

 

[Mechanic-al]

Zooming in on the crank sprocket in your diagram of the chain and tensioners, it looks like its located by a woodruff key. Extremely unusual, but these can wear and partially shear, which would throw the cam/crank phasing out.
The fact remains that there is a problem that the ECU is unhappy with. Have you tried any owner's forums online? Sometimes it appens that what appears to be a very obscure fault is well known amongst those familiar with that model.

Hi,
I saw no deformation on the woodruff key.
Unfortunately, I came here due to the owners forums being very suspiciously silent on this topic.
I agree that something is definitely wrong somewhere, And it's GOT to be something I've done !
I think the summary so far is that it's either wiring / ECU or timing.
So on the face of it I haven't made much progress but in fact it's been a fantastic education for all you guys' input.
I am extremely grateful for you taking the time to help me learn.
I've now got a list of things to check so I'm going to stop bothering you and go and get the checks done.

In order of difficulty...

Electrical checks:
CMP sensor earth.
Signal breaks when engine is manually rotated.
Scope signal and verify waveform.

Mechanical checks:
Crank sprocket marking / crank (woodruff key damage).
Crank sprocket on crank / TDC.
Timing OK?
Cam sprocket positions on cams.
I'll be back to update you asap.

Thanks again guys, I'm in your debt.

 

[OnlQQker]

6:04 on the video might shine a light

 

[Mechanic-al]

6:04 on the video might shine a light

Hi,
Thanks for investing your time here.
Very interesting clip, I laugh at the fact that an electrical issue elsewhere can throw up the rather specific and unrelated P0340 code. That's why Auto-electricians should be known as Auto-electric-magicians.

Without a scope, I'll have to cover the 'cheap / free' checks before I pay someone else to scope the system.
The alternator was new last winter, although I am aware that doesn't mean it's good now.
I'll add it to the list and get to it in turn.

Thanks again.

 

[brianmoooore]

Good call from OnlQQker. Modern car electronics are dependant on a good, clean and stable power supply.
I have a BMW 118d in the workshop at the moment, which has been laid up, unused, for 3 years. Apparently good battery fitted, and although it cranked OK, it showed no sign of starting. Instrument panel warning lights lit up like a Christmas tree. Read all the fault codes, cleared them, and cranked again. Connected the scanner again, and got all sorts of codes - a couple from the engine ECU (fuel pressure related), and loads more from all over the car, and the warning lights back.
Changed the battery for the 100A deep discharge one from my caravan, and the engine coughed and spluttered into life. Cleared the codes, the engine ones cleared for good, along with most of the body modules codes, and no warning lights.

 

[DPG]

Good call from OnlQQker. Modern car electronics are dependant on a good, clean and stable power supply.
I have a BMW 118d in the workshop at the moment, which has been laid up, unused, for 3 years. Apparently good battery fitted, and although it cranked OK, it showed no sign of starting. Instrument panel warning lights lit up like a Christmas tree. Read all the fault codes, cleared them, and cranked again. Connected the scanner again, and got all sorts of codes - a couple from the engine ECU (fuel pressure related), and loads more from all over the car, and the warning lights back.
Changed the battery for the 100A deep discharge one from my caravan, and the engine coughed and spluttered into life. Cleared the codes, the engine ones cleared for good, along with most of the body modules codes, and no warning lights.

Indeed. This is also a common cause of faults on Jaguars. A good example is the car showing 'Gearbox fault', but actually the battery voltage is low. Sometimes the gearbox warning can show instead of the low battery warning.

Having said that, I suspect the issue on my XF is the gear change module. Seems to happen in cold weather and I think I'm going to have to delve into the centre console.