Thanks JagV8. One small thing I did notice was that the connecter on cylinder 2 did not give the same satisfying 'click' that I got on cylinder 1? Should I try spraying it with something?
Puzzling that (apart rom the very small tremor at idle) the engine appears to be running well with no backfires (that I have detected) for more than a week?
Our old friend P0405 has now rejoined us as a pending:

 

Well it needs a good connection so is there some mechanical problem? Spraying won't fix one.

P0405 seems related to a circuit problem so I wonder if there might be a connection/wiring/etc problem with it.

Worth checking with care but it'll be painful and time-consuming.

I suppose both problems just about could (if the elec. diagrams show) related. Staring at circuits is another way to lose time...

 

Okay, today I had another backfire, clouds of smoke from both exhausts and Restricted Performance came on and them went off again in about 20 seconds? The smoking continued (lessening all the time) for some time. When I got home, I revved her in my basement parking spot and she misfired from her inlet manifold NOT HER EXHAUST?
These are the NEW codes etc:

 

With no service records and the miles you have I would replace all the coils and plugs to start with. Again if you find oil in the plug wells you will need to change the cam cover gaskets.

As posted above ALWAYS clear the codes when you read them. They must repeat before we can believe them. Otherwise you end up chasing your tail!
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Clubairth1 - Thank you, but I'm not chasing my tail I am disappearing up my own fundament!

 

Dear All,

I have ordered 8 new coils & plugs from the UK and I will double-check any potential Cam Cover gasket issues.

Are these of any help to you helping me, please?

 

Lets see what you have after the plugs and coils are replaced. Hopefully no oil in the plug wells but this is an older car so it's possible.
The other codes point to an EVAP leak and that might require a smoke test.
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Thanks Clubairth1, I have ordered Cam Cover gaskets as well by way of belt and braces!

 

Code P0456 - (EVAP Leak) is just about the only DTC I have not had! So are you referring to the attached Non-Continuous Monitors, please?

If so, please, how do I find out exactly what these component Id's etc. are referring to and what action must I take (while I await delivery of my new coils, plugs etc.)?

Regards,
Ray

 

You had a P0405 code up above. It's an EGR code and NOT an EVAP so sorry about that!
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[QUOTE=clubairth1;1800203]You had a P0405 code up above. It's an EGR code and NOT an EVAP so sorry about that!

No problem clubairth - At least I now know about the existence of such a thing as an EVAP system!

 

Hello NBCat, Thanks. What is a cold soak and what are oil boss seals, please?

NBCat - I'm just correcting this reply - I think the oil boss seals you refer to are Spark Plug Seals - Part Number: W0133-1656017 - Please correct me if I have this wrong.

So, what is a 'cold soak' and is there anything else I should replace while I have the Cam Cover off, please?

 

Yes you are correct. They are the same thing. They should come with the cam cover gasket set but be sure and check. I prefer the aftermarket Fel Pro brand over the factory.

Even if no leaks I would change the plug well seals as they will be hard as a rock by now and if NOT changed could very well start to leak after you disturb them changing the cam cover gaskets.
One tip? Smear a LIGHT coating of RTV on the both sides of the plug well seals. Remember a little dab will do ya!

If not included you can get them separately.

Cold soak just means let it sit overnight so the everything is cold.

I would not replace things unless you have a reason. You might also have an EGR problem but lets NOT change that out until you eliminate the misfires FIRST because misfires will cause all kinds of other errors.
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Clubairth1, Thank you. I have the Cam Cover Gaskets and Plug Well Seals winging their way to me as I type. I do believe you are right regarding the EGR problem. The P0405 code has been a consistent long-term stayer since day one!

 

Hi Ray,

I'm sorry to join your thread so late. You've already received excellent advice from some of our great experts, but I hope you don't mind if I chime in on the persistent P0405 diagnostic trouble code (DTC).

First of all, Jaguar's OBDII DTC definitions and possible causes often differ significantly from the generic definitions and possible causes, so it is important to only use the official Jaguar DTC Summaries guides rather than sources that list the generic versions. The guide at the link below is the most complete one I've found for the X350:

Jaguar X350 DTC Summaries Guide

Here is the listing for P0405:




As you can see, the possible causes are problems with the EGR valve electrical circuits, or failure of the EGR valve due to an open circuit in its stepper motor windings. The fact that your P0405 continuously appears as Pending suggests there is a recurring intermittent electrical issue. If a winding in the EGR stepper motor had opened up, you would expect the P0405 to be a permanent fault.

A common cause of a electrical circuit problems is corrosion or contamination in one or more electrical connectors or on any ground points referenced by the circuit. The EGR valve receives its ignition-switched power via Fuse 14 (10A) in the Front Power Distribution Fuse Box (FPDFB). With the fuse removed, you can test for battery power on one of the terminals in the fuse's socket. Connect the ground probe of your meter to a good ground point, such as one of the two behind the right headlamp. The terminal you find voltage on will be the power bus side of the socket. The other terminal connects to the EGR valve electrical socket on the Green/Blue wires.

Assuming that fuse is not blown and you find battery power on one of the fuse socket terminals, there could be a problem in the associated connector on the bottom of the FPDFB or electrical connector PI41, a 42-pin black-colored connector on top of passenger side suspension tower in the engine compartment. I found this connector information in the Electrical Guide, which you can download at this link:

Jaguar X350 Electrical Guide 2005

Just to rule it out, it would be prudent to do some basic tests on the EGR valve. There are four coils in the stepper motor of the EGR valve assembly. The Electrical Guide doesn't tell us the correct DC resistance of each coil, but with an ohmmeter you should be able to measure continuity (0 ohms or some resistance) across the following pairs of wires at the EGR valve's electrical connector (on the valve itself, not on the electrical harness):

Yellow/Blue (YU color code, Yellow wire with Blue tracer line), connector pin 3; to Green/Blue (GU), pin 5
Yellow/Green (YG), pin 1; to Green/Blue (GU), pin 5
Yellow/Red (YR), pin 6; to Green/Blue (GU) pin 2
Yellow/Blue (YU), pin 4; to Green/Blue (GU) pin 2

If you measure infinite resistance/overload across any of these pairs, that coil is open; or, if you measure higher resistance across one coil than all the others, the EGR valve should be replaced.

With the key in ignition position II (ON), you should be able to measure battery power between the two electrical connector pins with Green/Blue wires (pins 2 and 5) and a good chassis ground point. If you measure significantly lower voltage than current battery voltage, there is probably high resistance in the circuit and the connectors would be the first things to check. To measure the resistance, turn the key to OFF and remove it. Remove Fuse 14 in the FPDFB and measure the resistance from the terminal that does not have battery power to the Green/Blue wires in the harness connector at the EGR valve. The resistance should be very low, probably tenths of an ohm. If you find higher resistance, say a few ohms or more, clean the electrical connector pins with zero-residue electrical contact cleaner and also clean the one on the suspension tower. If that doesn't reduce the resistance, you may need to lift up the FPDFB and check and clean its connectors.

It is also a good idea to clean the ground points behind the headlamps, two on the right and one on the left. The studs, wire ring terminals and nuts are all made of aluminum, on which forms a microscopically-thin layer of aluminum oxide (a white powdery substance) which is an electrical insulator that impedes current in associated circuits, especially those that rely on sensitive voltage or current measurements. Note that the torque spec for the nuts is a very low 6.5 ft. lbs., or just over hand tight. Several members have learned how easy it is to snap a stud off the body by over-tightening the nut. For more information see this thread:

Earth / Ground Points Near Headlamps

Regarding the cylinder #2 coil connector that does not seem to fit securely, I have found that the rubber seals inside the connectors tend to distort with age, preventing the connectors from latching securely. It helps to wipe a little dielectric grease (a plastic-safe silicone grease) on the outside of the narrower or "inside" half of the connector to help the rubber insulator slide into place more easily. Just take care not to get any of the grease on any of the electrical pins or terminals because it is an insulator and can interfere with proper coil operation.

Cheers,

Don

 

Hello Don,
Your 'chime' may be late but it is very tuneful.......Thank you for such a detailed post!

 

Hello Don,
Your 'chime' may be late but it is very tuneful.......Thank you for such a detailed post!

 

After 123 posts over the past couple of months (every one of which has received a response), I would like to thank all my respondents within this excellent forum for their expertise and most of all for their patience!

I had oil in my Plug Wells, so I have taken the advice so generously given and have now successfully replaced my Spark Plug Boot seals, Cam Cover Gaskets, all my Spark Plugs and all my Coils. I had oil seeping out from the base of my Oil Filler 'tube' so I have replaced the seal and (hopefully) cured the vacuum leak that this must have entailed.

Everything appears to be okay; except I still have code P0405 and quite a strong smell of petrol at my exhausts. I am going to take the car out tomorrow and 'boot' it on a motorway to see if I get any more misfires.

Please, what must I do now about this damned EGR Valve sensor A circuit low? I have had the EGR Valve off and it is clean?

Regards,
Ray

 

Hi Ray,

Congratulations on your progress!

Regarding the P0405 code, have you conducted the tests I outlined in post #35, and if so, what were the results?

Cheers,

Don

 

Thank you Don - Do you know, I have been so focussed on getting these Cam Covers back on, I completely forgot about the tests you suggested in post #35! I do apologise for my rudeness!! How embarrassing!

I will get right on them in the morning and get back to you with the results

Don, your post is so detailed and yet clear enough for me to follow, you should consider it as a 'Sticky' for the EGR Valve......