2004 XJR Supercharged 4.2L V-8
Last six: G12607
Mileage: 95K
Until yesterday, running like brand new.

Recent Engine Work:

New Iridium plugs 20K miles ago
3 months ago, after getting P1647, I successfully replaced both upstream HO2 sensors.

Current Issue:

Jag rough idle started 07/22/2023 after driving 25 interstate miles, at times gunning her, she runs fine at speeds beyond idle. After noticing the rough idle, the amber check engine light appeared after a few miles and is now on continually.

Codes:
P0307 Cylinder 7 misfire directed
P1313 Misfire rate catalyst damage bank 1
P1316 Injector driver misfire - emissions damage./ Misfire rate excess emissions
P1000 Pending System check not completed since last memory clear./ OBD systems readiness test not complete./ Check of all OBDII systems is incomplete since last memory clear

Course of Action:

From Bob0927 in 2010:
https://www.jaguarforums.com/forum/x...y-ideas-32840/

I should first switch coil 7 & coil 8, to see if the diagnosis changes. If it does, it is likely a bad coil on #7.
If the code doesn’t change, then I should swap the fuel injector & if the error code changes to number 8, then the fuel likely injector needs to be replaced.

Questions:

Does my approach make sense? Any word to the wise from someone with experience with this issue?

As always, your help is immensely appreciated!

Steve

 

I believe your plan is correct. I would do the exact same thing myself in your place. Although I would just swap the coil with either of the coils next to it. The number 8 coil is usually a bear to remove. Also, I would pull the spark plug on 7 and inspect it. If the coil is bad it may be fouled. A bad spark plug could cause the misfire and pulling it will let you see if it is damaged or otherwise compromised. Good luck.

 

Hi, Steve,
You're heading in right direction! I had similar troubles last October though mine is NA. rough idle; damaged cat on message screen; limited performance.
Missfire code on #1; moved coil to #3; missfire moved to #3.
I just bought this car then. I replaced all coils and spark plugs.
Car runs like it was just from factory. 7kmi (weekend driver) and I have no complaints!
https://www.jaguarforums.com/forum/x...e-sure-264348/

 

As I understand it, #7 is the last cylinder on the passengers's side (US) or the right side of the car. If I am facing the car from the front, #7 is the last cylinder on my left.

 

The diagram is correct. The number 7 is next to the firewall. I would trade a coil from either 1, 3 or 5. As you can see number 8 is on the other bank and can be a little difficult to swap. Good luck.

 

Decided to switch coil #7 (misfiring) with coil #3 in order to see if coil #7 is defective.

#3 coil is dry as a bone; #7 has a small amount of oil on the spark plug end.

Haven't yet taken the spark plug out of cylinder 7 to inspect.

Just in case the presence of oil is indicative of something that can't be fixed by changing the coil, thought I should stop and inquire. Please let me know your thoughts.

Thanks very much for your help.

SS

 

Found this from 2018 (Think it for an XK8): https://www.jaguarforums.com/forum/x...-wells-204512/

Avern1 posted this:
"The oil in the plug wells comes from leaking cam cover gaskets. Since this is a recent occurrence you most likely have a plugged part load breather. It can plug at the cam cover and anywhere along the tube. At idle engine and under acceleration vacuum level is very high. Normally the part load breather would vent the vacuum to the intake where any engine blow by and crankcase pressure would be vented to the intake.
Since blow by pressure is building up it then causes cam cover leaks, oil blow by at pistons and fouling of the plugs. The first step is to clear out the part load breather. With the line removed the fitting on the cam cover has a small orifice that you will need to clean out with a small drill bit or awl. Then make sure the breather tube itself is clear. Clean all of the oil out of the plug wells, clean and dry the boots and put it all back together. Drive for a short time and monitor the plug wells, if they persist in leaking then the gaskets are damaged and you will need to replace the cam cover set."

Does this make sense?

Thanks for your help,

Steve

 

Yes but here is no part load breather on an X350 AFIK

 

Thanks, Meirion1. Long time; hope you are doing well.

Then, I need to replace the cam cover gasket?

This thread seems really good: https://www.jaguarforums.com/forum/x...cement-156327/

At least the passenger side is said to be easier.

Any other suggestions?

Thanks, Steve S.

 

I do not know if the amount of oil on the end of the coil is enough to cause a concern or not. Did you ever change the coil or spark plugs before? If not you really do not know the root cause yet. Although there is a seal on each of the spark plug wells that is probably responsible. I just swapped several coils on my car and 1 had a little oil on it as well. I did replace all the spark plugs in 2018 so I know the oil was not there then. However the amount of oil is not enough to do more than get my hand a little dirty when I pulled the coil. The inside of the spark plug well has no accumulation on the spark plug itself and the coil does not exhibit any sign of cracking or otherwise being damaged. Accordingly I am not to concerned. It I had another issue I would pursue it further, but for now, I have seen so much coolant/steam and even water from me hosing down the engine to wash off coolant residue I am not going to worry about it.

The Airtex Wells coils I replaced the Denso units with have a larger seal that fits over the well and may not seal out 100% of all oil fumes all the time. Also it is most likely the seal for the spark plug well is "seeping" a bit. I usually try to concentrate on one problem at a time as even that will often present additional challenges. I would only address it now ,if you pull the spark plug and there is enough oil on the plug itself to interfere with the spark. If there is a couple to teaspoons of oil in the plug well then I would deal with it. Otherwise I try not to get sidetracked when sorting an issue like a misfire. The more things you do now may make it more difficult to find your original problem. Every time I move something I worry about the aged plastic parts breaking or a electrical wire or connection being damaged. Heck when I pulled my #3 coil the brass insert for the hold down just spun and the bolt would not come out. Accordingly I had to deal with that problem before I could even test the coil/misfire issue. Good luck.

 

One variable at a time appeals to me!

As you know, #7 is by the bulkhead & doesn't allow for visual inspection. I will see what I can find with fingers or a cloth.

Unless I'm convinced that there is oil accumulating, I'm inclined to se if it is the #7coil. If it is, I might make the repair and monitor. if I ultimately have to replace the gasket, according to my research on this site, the driver's side is "easier".

I did change the plugs with the improved irridiums about 20k miles ago. There was no sign of oil.This happened after I had done some pretty aggressive driving. Thought being, you need to blow the carbon out. Maybe I blew the gasket out, too!

Either way, I sincerely appreciate you for your thorough & experienced response! You are a scholar & a gentleman!

Best,

SS

 

OK, I made a paper towel tube & sent it down #7 & didn't pickup any oil. I will send a pipe cleaner down to be sure that I check below the top of the spark plug.

Plan of Action:

Swap the coils to ascertain if the coil from 7 is shot. If it is, I will order a new one. I understand Denso is the original manufacturer.

While waiting on the new coil, I will inspect the #7 plug & replace it if it appears necessary.

If the problem goes away, I will stop for now. Realizing that, if the problem resurfaces, I may have to replace the gasket(s).

Any thoughts?

Thanks & best,

Steve

 

I did all eight coils and plugs. Bank1 is easier. For me it was first two months I owned the car. It was making more sense to to do all in one sitting. I see you have replaced plugs recently...

 

Interesting. Seems the reader now says "stored" for each of the aforementioned codes?

It did not indicate a misfire in #3 where I placed the #7 coil.

I don't think she is idling roughly either?

So either the coils are ok, or the misfire is still in #7, but I can't feel the rough idle; so, there may be something else the matter with #7.

If it is showing "stored" and no other codes other than the original ones, what does this mean?

Thanks,

Steve S.

 

Oops, nope, wishful thinking. Still idles roughly and the amber check engine light is still on.

Will check # 7 spark plug.

 

@04Xjrsteve Check DTC: swapping coils will not eliminate rough idle; just missfire will move from #7 to another cylinder. DTC identifies which one!

 

Thanks, Big Koshka. The codes did not change, except that, the word "stored" appeared by each one. That is what threw me & had me think that the problem had mysteriously fixed itself.

I will check the plug in # 7.

If it isn't the plug, I think the next thing is to consider the fuel injector.

I also want reaffirm that the cylinder configuration is as we think it by the diagram above.

Best,

Steve

 

@04Xjrsteve did you cleared code? Stored could mean that computer does not see it happaning in couple of cycles, it "stores it", but will not lit up yellow light!
On injectors: Check continuity; check if signal comes to ejector! If signal comes and injector doesn't fire, replace injector. I think you will need somthing more sophisticated than mulitmeter, or multimeter capable measuring frequency (period)

 

Thanks again, Big Koshka.

Will clear codes this evening (in about 8 hours). Still plan to check the spark plug first.

If it was the coil, I would think that I would have received a new error code for #3 since that is where I moved the coil from the misfiring #7.

 

Yes! In my case it did move together with coil! There are plenty other factors in play. Did you raced engine? Tried to drive it a little, give engine a load, to see if DTC coming up? In my missfire did not happened every single time...Try to 'provoke' it and then read DTC to see if missfire moved.