Jaguar XFR Bad Missfire on one bank

[Trailking]

Jaguar XFR bad missfire on one bank
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!

Missfire is hard and the car is not really drivable.

What I know:
Car is a 2009 with 109k, has been well maintained.
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!

[XFRFred]

I'm going to say fuel pumps might need changing.

When i had the XFR, which showed similar symptoms after an engine change, it was the fuel pumps that caused the rough running.
There's no fuel filter that can be changed independently, it's all within the pump housing.
The pumps were replaced after all the injectors, but ran fine after the swap out; there's two, may as well do them both at the same time.

BTW, great lurking!

Edited by XFRFred on Sunday 13th September 08:46

[Trailking]

Thanks Fred,

I did question the fuel pumps, but the fuel rail pressure is fine, infact it is 50% higher than the demanded pressure.

[XFRFred]

The pressure in the line was ok too, prior to the pump replacements, which is why they were the last to be replaced in the fuelling system.
XFR was running fine for a little while, maybe a year or so after all the replacements.
However what did happen over time, was the pressure would be lost in the line, as soon as the car was turned off. To which it wouldn't start straight away, when trying to turn it back on.

As a work around, you needed to prime the line, so press the start button (without holding the brake). Once you've heard the pumps had stopped priming, put your foot on the brake and press the start button again, and it would fire up without any issues.
Never got around to fixing it, and was sold on.

[Penelope Stopit]

Trailking said:

Thanks Fred,

I did question the fuel pumps, but the fuel rail pressure is fine, infact it is 50% higher than the demanded pressure.

Surely that's a fault

50% higher pressure than it should be means that too much fuel is injected when an injector opens

Hope this helps

[STattam]

Penelope Stopit said:

Surely that's a fault

50% higher pressure than it should be means that too much fuel is injected when an injector opens

Hope this helps

I assume the fpr would sort that out though.

[Trailking]

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

[Trailking]

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

[fatboy b]

Is it a modded engine? Supercharger pulley?

No rockers on these engines.

[liner33]

Timing chain jumped ? Usually a case of when rather than if on these engines

[John Locke]

If the compression is down, then it's cylinder head(s) off time, unfortunately. Timing chain and tensioner problems aren't all that common on these; there are enormous numbers of these engines around, and you only read about those that go wrong, not the ones still trouble free at 250,000 miles.
Good fortune with it, and please keep us up to date with findings and progress.

[fatboy b]

John Locke said:

If the compression is down, then it's cylinder head(s) off time, unfortunately. Timing chain and tensioner problems aren't all that common on these; there are enormous numbers of these engines around, and you only read about those that go wrong, not the ones still trouble free at 250,000 miles.
Good fortune with it, and please keep us up to date with findings and progress.

Based on the ones I've heard start up - I'd say the problem is quite widespread with the tensioners. I'd estimate 30% are ticking timebombs. But some of those may never fail - just make a noise on start up.

[liner33]

fatboy b said:

Based on the ones I've heard start up - I'd say the problem is quite widespread with the tensioners. I'd estimate 30% are ticking timebombs. But some of those may never fail - just make a noise on start up.

Its massively widespread its a design fault . Samcrac on youtube details it on his Range Rover that he bought, basically the tensioner wears through the guide resulting in a loss of tension, there is a redesigned guide but they were still fitting the naff ones up well into 2014 at least

[fatboy b]

liner33 said:

fatboy b said:

Based on the ones I've heard start up - I'd say the problem is quite widespread with the tensioners. I'd estimate 30% are ticking timebombs. But some of those may never fail - just make a noise on start up.

Its massively widespread its a design fault . Samcrac on youtube details it on his Range Rover that he bought, basically the tensioner wears through the guide resulting in a loss of tension, there is a redesigned guide but they were still fitting the naff ones up well into 2014 at least

There's another redesign mid 2019 too.