Hello all,



Really hoping someone can help me get to the bottom of this, a few weeks ago the car started misfiring badly a few miles from home. I limped it home and have been trying to fix it ever since! I really miss driving the Jag!



Missfire is hard and the car is not really drivable.



What I know:

Missfire is in cylinder 8 initially then spreads to other cylinders in Bank 2 (left hand side of engine) once can comes off cold idle.

Coils and plugs have recently been changed and are functioning fine in bank 2

Injectors have been changed on Bank 2, no improvement.

Injector wiring continuity it fine.

Catalytic converter is not blocked.

Fuel rail pressure is fine in SDD

Fuel quality seems fine ( I have pulled a sample using the lift pump and it smells fine with no water).



Fuel trims are way off Bank 1 compared to Bank 2,

Bank 1 +30%

Bank 2 -30%



Next steps are a compression test, does anyone know what results I should get for good compression?



Any other thoughts? Things I should check?



Thanks all!

 

What's the age of the car? And I assume this is the 5.0l SC XFR and not the XFR-S?

 

It is a 2009 XFR 5.0 SC

it has 109K miles

 

Ok, so did the compression test and it’s not great news.

Number 8 has no compression.

Next steps are to pull the supercharger and bank 2 rocker

 

Ouch. Was there any noise suggesting valvetrain issues? I guess you could have a dropped valve or similar.

Keep us updated - always appreciate learning of causes of engine failure.

 

Nope, no noise indicating impending doom! Will keep you posted as to the outcome.

Borescope comes tomorrow

 

Any news yet?

 

Update:

I found the issue, dropped valve seat on the LH intake.

in the process of stripping to repair!

I have found at least one other example of this happening in this forum. No idea how common an issue this is and what the root cause could be. Anyone have any suggestions?

I was thinking overheating but I have had no temperature warnings.

 

Also, does anyone know the correct tool for removing the head bolts?

I have tried a RM12 ribe socket, this is very close but not a perfect fit!

works for removal but would not use it for refitting.