Dear Forum,
I have a random but ongoing misfire on No.2. Codes P0302, P1314 and (just once) P1316. I do not physically notice them - Until today, when I felt a definite miss and Restricted Performance flashed up and then disappeared again immediately. There is no oil or debris in 2. The coil and plug in 2 are new. The plug is textbook perfect - No soot, no oil, just a light sandy-coloured coating on the electrode. The code stays with 2 even if I swop out the coil and plug. I have noticed that Bank 2 Fuel trims tend to be negative long and short? With a bow to JagV8, this goes away at 2,500 revs (see pics below). Could this be an intermittent fault with the Injector at No.2? Obviously, I don't want to start messing with them if I am barking up the wrong tree completely?

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UPDATE:

I have completed Pin Tests G290075t2 - Ignition Coil Supply Voltage Circuit and G290075t3 - Ignition Coil Ground Circuit for Cylinder No. 2 and it passed both tests. I cannot go any further with these pin tests because I do not know how to disconnect the ECM electrical connectorP101.3?




DTC's


Fuel Trims Idle


Fuel trims Idle (graph)


Fuel trims 2,500 revs

 

 

Thanks Jazzyjags. I replaced all coils and plugs with new (OEM)a little over six months ago. The code stays with cylinder 2 even if I swop out. I will put your Cat comment on a back-burner for the moment, to be returned to if necessary. In passing, I imagine all the cylinders on the side with the blockage were affected, was this the case, please?
Right now I want to try to find out how to conduct Pin Test G290075t4 etc first - Finish off testing the ignition circuit for that cylinder.
However, I cannot go any further with the Pin Tests until I find out how to access the ECU in order to test the pins on its end of the Ignition Loom.
Please, do I remove the Glove Box to gain access and if so, how?

Forum, I just found Don B's excellent posted reply to a similar post as follows: https://www.jaguarforums.com/forum/x...ration-175256/

 

The ECU is located under the glove box. No need to remove it. There is a black fabric cover over the footwell in the passenger side and a bracket or something like that, don't remember completely. Easy to remove though, I did it in like 20 mins. However to disconnect the ECU from the harness, you will have to remove your cabin filter and the box that holds it in the rear passenger side of the engine bay. The harness plugs into the ECU through the firewall. It's held on tight with a 5 point torx star bit. You can get a set on Amazon for cheap. Once you loosen that and I think 2 regular bolts on each side, you can go back into the footwell and wiggle out the ECU.

Make sure you disconnect your battery before the removal!
Best wishes

 

Thanks again, Jazzyjags. Just to clarify, please could you confirm whether your Cat - induced misfires affected just one cylinder or all of those on the blocked side?

 

No problem. Actually no misfire at idle. But as the revs went up I'd get more. Started with just 2 cylinders, eventually 7 out of 8 as time went by and the cats got worse. Also, our not in UK are you? Because I'm not sure about the ECU location on a right hand drive x350, not sure if it's the same just mirrored etc ... That was my experience with my Xjr here in US

 

Just to double-check, my copy of Powertrain DTC Summaries lists P0302 (logically) as Cylinder 2; however, my copy of X350WorkshopManual shows it as cylinder 3!! I am pretty sure that it refers to cylinder 2, but please could someone confirm which is correct?
While you are kindly at it, please could you explain Check the ignition Coil Ground Circuit for high resistance - Cyl 2 P122, pin 2 (GB) and EM29 pin 08 (GB); I think I understand everything bar where I find EM29 pin 08?

 

P030x is cyl x.

 

Thanks JagV8.
I'm now waiting for a T30 Tamper-Proof Torx to be shipped to me so that I can finish ruling in or out faulty Ignition Circuits. After that, I guess I will need to look at Cylinder 2's Injector? Then (if it becomes necessary) I suppose I must look into Jazzyjags suggested clogged catalytic converter? Please, am I heading on the right track, do you think?

 

Conclusion to this post (I hope)!

To rid myself of this persistent Cylinder 2 misfire, I have been chasing Coils, Plugs and Ignition Circuits for some time.
Then:
I put Liqui Moly Injection Cleaner in my tank and I have now had three engine cycles without a misfire code!
Keeping my fingers crossed!!
I last used this cleaner 4 months ago? Perhaps I ought to do so every three months?? OR should I take a closer look at this particular Injector? What do you think?

 

My suggestion would be to run it until you see the problem again, but plan on replacing or having the injectors serviced (plenty of performance shops will clean and flow test and provide results). Having them cleaned would save a bunch of money, but mean you have some down time. I wouldn't only focus on #2's injector as the others have lived the same life, that's just the first to go.

Seems like you did everything necessary on the ignition side already. Since you noticed a difference with some injector cleaner in the tank, it's likely not a compression issue, so I'd feel confident to chase down the injectors if it starts acting up again.