Hi there from The Netherlands, we are a little desperate. We are a workshop with big problem, and local jag dealers won't / can't provide us with the right information. (they have expelled the customer from there workshop, saying that they couldn't help him).

Long story.
Ill try to keep it short as possible.

X-type Estate 2.5 V6 AWD. MY 2006

Customer came in, running on 4 cylinders.
Cyl 3 and 5 no compression.

So we rebuilded the cylinder heads / valves.

Car is running on 6 again.

Nice you would think, but.... Now the problem what caused the dammaged to the valves / cylinders heads pops up!

When acceleration Bank1 is running lambda 1.200, much to lean!!!

At cruising speed (80kph) Bank2 is missfiring, this causing a lean mixture. (missfire -> causing O2 in the exaust manifold).

So we checked everything possible.
Sparkplugs. (new OEM).
Coils.
Airleakage. (pressure with smoke).
Changed Injectors.

Now we are this far.

We have disconnected all the lambda sensors (4).
Put in a Air fuel ratio sensor (broadband lambda sensor) on the place of the original Lambda sensors (precat) and the problem stays the same.

So you can put it as this.
Its something mechanical. (the ECM cant / wont correct the mixture, because it cant check it and the engine will run in open loop).

Injector time both banks should be the same. But there is a difference bewteen the injector times on Bank1 and Bank2. More then 2 miliseconds when acceleration!

MAF, Throttlevalve and MAP sensor are used for both banks. So these cant cause the fault.

Then there stays the ECM, Cranksshaft sensor and Camschaft sensors AND the VVT system for each bank. (somewhere there is the problem)

Now the quesion: can cause a mallfuncting VVT valve/system, that the injection time on each bank differs to each other (bank1 / bank2). Causing the lean mixture / missfires on the banks?!?!

And is there a way to check the workings of the VVT?
We do a lot of BMW, we can run a test cycle checking the VVT. But for jaguar we dont have this option.

We have a labscope.

But we think its something with VVT. An extra reason to think this, when we disconnect the VVT valves the Lean mixture at cruising speed changed to the other bank. (from bank2 to bank 1).

Sorry for my long story... but i hope someone can help us.

2 side questions:
On jaguar Topix there are 2 bulletins (i cant read them, dont have a creditcard).
With discription:
A303-024 - Engine Misfire with possible diagnostic trouble code(s) (dtc) stored

A303-10 - Interpretation of DTC P1582 'flight recorder' data Stored

Any one knows the contents of these bulletins?

 

The injection times are exactly the same in openloop for bank1 and 2.
(lambda sensors disconnected, airfuel ratio mearing at precat sensors). This whas not measered correcly in first instance.

And still one bank is much leaner then the other! So this has to do with the breathing of the car. (they get the same amount of fuel).

We will take of the camshaft cover and manualy check there is something wrong with VVT.

Regarding the service bulletin:
A303-024 - Engine Misfire with possible diagnostic trouble code(s) (dtc) stored

See the attachment. A ground cable must be checked and software update.
We will see into this.

 

First of all, I apologise if I tell you something you may already know.

I am not an engine technician, but I have a copy of the technical notes for the X350 model, which uses the same V6 as the X-Type, albeit 3 litres instead of the 2.5 of the X-Type you are looking at, (which also offered a 3 litre engine as well).


This engine is a well-known Ford unit, and is found in several US Fords. The technical notes state that the VVT is of the continuously variable type, which allows the position to be varied at any point over a 30 degree range rather than having only two settings at either end of the range.
The notes especially refer to the S-Type and the X-Type as the first models with the V6 to start using continuously variable VVT, instead of just two settings, which was then used by the X350, so the system on the X350 is the same as your car under investigation

According tothe notes, the VVT variation is acheived by the ECM rapidly pulsing the energising signal to the control solenoid. This pulsing allows the VVT shuttle valve to assume a position at any point between the limits of its travel, and is continuously controlled by the ECM to maintain the shuttle valve position where the EC desires it to be. Feedback is provided by the camshaft position sensor, which transmits signals to the ECM on the position of the camshaft which the ECM can compare to the crank postion sensor, and thus calculate the amount the camshaft is advanced or retarded.

It seems to me that this feedback is crucial in correct fuel injections, because if the ECM does not receive the correct feedback on the camshaft position, it could give false pulse signals to the fuel injectors based on the fuelling map in the ECM. Whilst each injector is fired individually, the pulse length may be common to each cylinder bank, however, I cannot give any more information, as the technical notes do not go into detail on ECM operations.

However, I would certainly be checking the camshaft position sensor on the bank with bad results.

Tot ziens !

 

Don't worry about the A303-10 bulletin, that is just describing how to clear the Code P1582. That 'code' is not a DTC really, it indicates the flight recorder function has data stored. That is used mostly for confirming throttle faults and maybe catching something useful for engine stalls, won't be of any help to you.

My first thought after reading the original post a few times is damaged catalysts. Unfortunately about the only way to truly confirm that is substitution. Maybe a bore scope put in the downstream O2 sensor holes to check the bricks inside. Messed up catalysts screw up the engine breathing and manifold pressure in particular. Then the misfires flood the exhaust with oxygen as you mentioned. Sensor readings on an engine running that badly are not much help sometimes.

Good luck!