I have the 5.0 liter non supercharged 2010 XK with 93500 miles or so. My car started running rough, and when I got home I ran a scanner on it. It said that cylinder 2 pressure was low and had misfired. There were also 15 more errors in the Engine Control Module, including ones mentioning all 8 cylinders as having misfired. Previously, some times the car would run rough, but if I would turn it off and restart it would return to normal. This time it hasn't. The check engine light and Restricted Performance were thrown. I had hoped it might be bad gas from condensation with all the yo yo weather we've been having. That was the case with my inlaws Subaru, but it doesn't appear to be the case here. I use only 93 octane Shell gas.

I had planned on replacing the sparkplugs but some research also indicated this could be caused by a catalytic converter issue. I'm open to any help possible.

Thanks!

 

This is something I have experienced on my 4.2 SC, does it smell of petrol/gas when you first start it? After a few minutes does it settle down and idle normally? will it run normally when driving lightly not going full send etc? if so the it could be a leak on the fuel rail, it need to keep pressure at around 56psi. One thing that can leak on the rail is the fuel dampers as the ethonol in the fuel eats the seals, you can get replacements in the USA from injector planet they are ford items $49 each in the USA or pay jag £172 each or £1400 per side for new rails, its probably easier on the none SC model to replace. Mine got to have the SC out which is a big job. I got an inspection camera to check mine out for leaks as it means you can check the injector seals for leaks etc, check fuel pump is delivering enough. One other area to start is a product called Profi Fuel Max, in a carb cleaner / fuel stabilizer and helps dissolve enamel just in case of a build up or something but as all 8 have missed (seen on mine) I would look at fuel and ignition

 

Have you ever had the cam chain tensioners checked or changed? Your symptoms sound like the classic 5.0 tensioner failure. I would not run the engine again until these have been checked. You can do a quick check through the oil filler cap, I believe.

If the tensioners have never been changed, I'm afraid that the engine may already need an expensive rebuild or replacement.

Richard

 

Misfire #2 may be a bad ignition coil on that cylinder.

 

I would not be surprised if it is fuel related. The constant freezing/thawing has caused one of my other cars to run rough till enough fuel came out. A local Jag mechanic, when I told him what was up, said it was likely a "tune up issue". I have had the car parked and have been reconditioning the battery. (It's pretty new and good, but the XK continually runs it down for reasons I'm not sure of.) I will see if anything corrects after I check the tensioner through the oil cap.

 

I will check the tensioner through the the Oil Filler area and check to make sure it is taut. I mentioned this possibilty to a local Jag mechanic but he felt it was unlikely in my case. Still, if tension is loose I don't want to take any chances so I will check first.

 

Yeah, that was what the mechanic I checked with thought. The battery has been up and down and some codes could be because of that. I have the car set to get the plugs replaced, all coils to be checked and replaced as needed and to get my Valve Cover Gasket replaced. I hate to outsource the plug replacement, but quite a lot of disassembly seems to be necessary to get to the plugs on the 5.0 engine (4.2 looks much, much easier.) This should occur next week.

My plan is to check the tension, if good, then put the reconditioned battery on the car back online and see how it runs. The car has 93500 miles or so, so I believe it is time to get the plugs replaced and coils inspected given the mileage and no indication it had ever been done before. The Valve Cover Gasket doesn't have a huge leak, but needs to get done as well. Is there anything else to replace while they are replacing the Valve Cover Gasket?

 

Just gonna throw it out there..

Had many problems with shell gas..


especially when winter hit..

not sure if its an additive they put in?

wife refuses to go there.....

made her Jag run rough!

 

Well, timing chain is taut. Reconnected Battery and it started up and is running smoothly. No misfires as far as I can feel or hear. Finally, had a bit of sun when I got home with warmish temps so I could look at it. Even so, I'm going to get the plugs replaced, coils inspected and valve cover gasket done as its time to get those looked at, and this isn't first misfire on #2. I will drop it off Monday with an independent shop. Glad it has not been anything engine destroying ::knocking on wood:::

 

What does cylinder 2 pressure was low and had misfired mean? How did you measure the pressure? Did you do a compression test?
You need to post the codes. The real numbers. That will tell you what to do next.
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Sorry for the delay in response. The old codes were gone. What I had when I used my code reader were the following:
P0345-31 State: Pending Camshaft Position Sensor A circuit (bank 1 or single sensor)
P0345-31 State: Pending Camshaft Position Sensor A circuit (bank 2)
P0340-31 State: Pending Camshaft Position Sensor A circuit (bank 1 or single sensor)
P0500-81 State: Intermittent Vehicle Speed Sensor A
U0402-68 State: Intermittent Invalid date received from transmission control module
B1B01-67 State: Permanent Key transponder
U0422-81 State: Intermittent Invalid data received from body control module
U0415-00 State: intermittent Invalid data received from ABS control module
U0197-00 State: Intermittent Lost communication with the telephone control module
U3003-17 State: Intermittent Battery Voltage
B111A-11 State: Intermittent Number plate lamps
B11DB-87 State: Intermittent Battery monitoring module

A number of these are probably a result of the battery going flat which is occurring due to some process on the car that I am unaware of (though I saw a technical bulletin about updating software to make this less common, which I don't think was done on the car.) I've purchased a trickle charger to help maintain charge overnight to prevent some of these errors and lower voltage situations.

The car is currently having spark plugs changed. The coils were tested good. They are repairing the valve cover gaskets. There are also leaks at the Oil Pan seal and the front seal which the current shop says they don't have the equipment to address, so I will have to have that work done elsewhere.

 

So, your initial guess is a fuel related problem, so you have the spark plugs replaced?
Sometimes, when running rough, you cycle the ignition and it runs smooth?
What might cause that?
You carry the problem to a less than full-service Jaguar independent and tell them to replace the plugs, check the coils and repair oil leaks?

Why not tell the shop about the intermittent rough running problem?
Maybe they are competent doing diagnostics, even though not capable of crank seal repairs?
They are OK with repairing half of the leaks?
How do you know if the valve cover leaks are corrected?

The 5.0L fuel system is direct injection (high pressure) so is not going to have the problem described for the 4.2L.
However, it still relies on a tank mounted fuel pump, with integral fuel filter to deliver fuel to the HP pumps.

Proper/complete diagnostics to determine the actual problem(s) prior to beginning repair is recommended.
Consult the full-service shop and ask for diagnostics.

The diagnostic codes shown are all temporary (except security) and may be associated with low battery voltage.
If your battery is not holding 12+ volts overnight, look there first.

Finally, check the voltage before starting, and monitor while running.
Excess oil leaks can "disable" the alternator output without indicating a failure.
That is, output is marginal. Not sufficient to maintain the battery but not indicating a failure.

Good luck.
Keep us posted on your success.

Bill

 

Fuel Pressure Sensor Slow fail, no codes - Jaguar Forums - Jaguar Enthusiasts Forum

See Post #7.

Keep us posted on your success.

Bill

 

Thanks for the heads up. This does describe the intermittent nature of the rough idling I am experiencing. It also seems like a relatively easy repair, provided you take the time to release the pressure in the fuel rail first.
I was looking up the Fuel Pressure Sensor in a Jaguar XK Fuel System guide, and it lists both a Fuel High Pressure Sensor and a Fuel Low Pressure Sensor. Based on the thread you provided, it appears to be referencing the High Pressure sensor. Just wanted to make sure I was correct.

 

Is this the FPS? It's at the end of the fuel rail.

 

Pretty easy. IIRC, with the engine running, pull the fuel pump fuse.

 

It says the fuel pump fuse is F33 located in the rear seat compartment fuse box. We pulled it, but the car never sputtered out. Is there another fuse that should be pulled so we can depressurize the fuel rails?

 

Does anyone know the size of the socket to get the FPS off? I thought it was a deep well 15/16 but that is not big enough to turn the sensor.

 

See post #12 in this thread:
Fuel Pump Fuse

 

Metric 27 Deep Well socket will remove the FPS on the 5.0 liter XK engine. It looks like this... We could not figure out how to remove the wire harness which made using a deep well socket kind of tough on the wires. Does anyone know if it is supposed to be removable?