May be worth me mentioning that although I have a fresh P0302 as a pending DTC, I did not notice any actual misfires? Could this (potentially) low reading on pin 4 be fooling the ECM into 'believing' that I have a misfire?

 

No.

The PCM will detect misfires long before you do.

 

Thanks JagV8,
I know it's nearly Christmas and Don (across there in the 'Beautiful Mid-South' USA) is 10 hours behind me, but do you have any ideas what I might try next, please?
All I want for Xmas is a code-free Jaguar - Now you know that at 62 years of age, I must still believe in Santa Claus!
Regards,
Ray

 

I am getting similar voltage and resistance readings on the other bank; for example: Coil 5. 11.30 volts (I'll be recharging my battery tonight) and 1150 for resistance pin 4 to earth. I really do not understand what relevance 1150 has to the more than 10,000 ohms I am supposed to be getting - But surely the key point here is that the reading for Coil 5 (with no pending DTC) is virtually the same as that for Coil 2 (with a pending misfire DTC)?

Unless:
a) I am not taking the measurements properly. Obviously my multi-meter cable will not reach the negative battery terminal so I am using a nearby earth.
Or b) My misfire is being caused by something other than plug, coil or connection? Perhaps the injector?
However, wouldn't a faulty injector show up as a DTC all of its very own?

 

Don & Co my Christmas wish has come true - I now have a Jaguar XJ8L with no DTC's!

It decided to clear the last remaining 2 DTC's of its own accord on Christmas Eve.....

I would like to thank you and all the Forum Members who have helped me get from 6 DTC's to none and to wish you all an enjoyable and relaxing Christmas break!

I look forward to annoying you all again in the New Year.

 

Hi Ray!

Sorry I've been incommunicado but I've been in a race to finish several work projects before the holiday break. Congratulations on your success. The pending P0302 may have simply come from a time when you ran the engine with the coil electrical connector not fully secured. If it ever returns, check the DTC Summaries and Workshop Manual sections on P0300 for the fairly long list of possible causes.

Merry Christmas!

Cheers,

Don

 

Dear Forum,
Here are my fuel trims after cleaning oil from plug wells, replacing plug boss seals and cam cover gaskets, replacing all plugs and coils and repairing loose wire in EGR Valve connector.
Currently no codes and all seems fine.........
Apart from the occasional cloud of black/grey smoke at startup (renewing fuel filter on Saturday) and the very occasional gear slam (well, once) when pulling away from lights (followed by a cloud of black/grey smoke) and on another occasion, a sudden and unexpected change-down (once). Neither event caused any lights or codes?
Question: Non-Continuous Monitors may need the longer run I will be taking on Saturday? - But having said this, I could well be wrong since I don't even really know what they are!

More important question: Am I reading these fuel trims correctly; my bank 1 LTFT is enriching by 7% to cure a bank 1 lean mix and keep my bank 1 STFT at 0%? If so, could this be a vacuum leak on bank 1?
Regards,
Ray

 

Check the readings again to make sure they're about the same and then rev to about 2500 and watch the trims (for 30 secs or less, it's not critical, just till they settle).

With an air leak they should head much nearer 0.

 

Hello JagV8 - Thanks. Done as you suggest - Pic 1 at after warm-up, pic 2 after 2,500 revs and pic 3 after rest; not sure whether or not the results are particularly telling? I am taking a decent run out on Saturday, so I will try again after that - See if there is any change? Also on Saturday my fuel filter will be renewed (probably from birth 100,000 miles ago)!
Meantime, there does appear to me to be an imbalance here - Am I reading this correctly as a lean bank 1? Any thoughts, please?
Regards,
Ray

 

They don't look to move much so probably not an air leak.

What is the actual problem now? I don't really see one.

 

JagV8, perhaps then the problem is me!!!!!!!
My (limited) understanding is that if all the long & short term fuel trims are around zero, all is well? However if (say) bank I has a plus 7% LTFT it is because the bank 1 STFT is too lean? Is that right? If so, is 7% something to look at?
I am under the (mis?)apprehension that bank 1 LTFT of plus 6-7% opposed to LTFT Bank 2 of close to zero is an imbalance. If this is approaching normal for a 13 year old car with 100,000 miles on the clock, please say so and I will stop being such a pest - After all, you guys have taken me on a 'rollercoaster ride' from 6 DTC's to zero!!
Regards,
Ray

 

Ideally LTFTs are closer to zero than 7 but it's not a big tweak for an engine of that age and miles.

It MIGHT hint at a problem but it might not and you could chase it forever. If you'd rather go on hunting that's up to you but I'd leave it unless (or until) I had something clearly wrong to chase.

STFTs by their nature swing around somewhat. If consistently one way then LTFTs move and the STFTs reduce. (Thus the S and L.)

 

Thanks JagV8 - Got it at last......Please excuse my trapped in the 1960's/1970's mechanical world understanding of things new; I got 350,000 miles of trouble-free motoring out of my Rover (Buick) V8 3.5 litre, but that was back in the days before emissions were more important than efficiency and performance!
And thanks for all your help. As an ex-matelot with much experience of 'Yorkies', I recognise that your economical responses to Posts do you justice as a 'Tyke', but (and I quote) "See All, Hear All, Say Nowt; Eat all, drink all, pay nowt. And if thou ever does owt for nowt, do it for they sen!
You may well be an unusual Tyke because you are generous with your time for no fiscal reward and I wonder what our American cousins will make of my comments!

Ray

 

They'll probably not recognise quite a few of the words...

Cheers, though!

 

Well, I had my fuel filter renewed and then went for a good long run today. Got a couple of miles up the road and had another example of a both heard and felt (rear of car very slight dip) 'clunk' sound (missed gear?), followed by a great cloud of grey smoke out of the exhausts and a pungent smell of burning rubber. Has happened a couple of times before, but usually followed by misfire codes. I have no misfire codes. Later, I got a pop-pop misfire from my inlet when revving at restart and later again, a multiple popping sound from the exhausts and more smoke. The smoke comes and goes? On the way home, I got the Gearbox Fault light on again with electronic restricted performance. Got back home - No misfire codes, pending code P0783 for the transmission and no smoke. Switched off and then back on again, gearbox fault light not lit. When the car is running well it runs very well, and then for some inexplicable reason, it seems to 'throw a wobbly' and then smokes for a while until it stops doing so? I still have a very slight 'tremble' at idle (MAF clean,Throttle Body clean), not plugs, not coils, not EGR Valve?
Could this be a timing chain tensioner? Throws an occasional mistime and the entire injection of fuel burns in the exhaust? Could the burning rubber smell be my catalytic converter being damaged? Here are my fuel trims (which appear to my untrained eye to show both long and short readings for bank 1 trimming as for lean) for anyone brave enough to take this one on!

 

Guys, I have started a new post: https://www.jaguarforums.com/forum/x...-valve-195032/ because it is a new subject and a search for that subject will quickly turn it up, maybe for another members benefit?
But since it is still related to this post and I do not know what the etiquette is I have posted this? Jackra_1 has already remonstrated with me (quite rightly) for making it difficult for people to help me by jumping from post to post and if I am doing this again, please tell me the correct way to behave in future?
Regards,
Ray