Side note: I am not sure if anyone is familiar with Dave in VA's story with his XK8, but he had similar codes (his misfire was #8) an it turned out to be that there were 3 bad coils even though he only had a misfire on one cylinder. He discovered this only after swapping literally every other coil into the misfiring cylinder. Granted, I think his symptoms were worse than mine, but now every driver's side bank coil has been swapped into 7 and I have been thrown the same codes. I may just buy a new coil and put it in to eliminate the Dave in VA scenario. Thread to that is here: https://www.jaguarforums.com/forum/x...-147929/page5/

Is it possible that the connector on 7 could be fried/dirty/otherwise causing issues?

To sum up, things I have tried or have been done:
- Techron
- Injector swap (also fuel filter replacement)
- New proper NGK plugs
- Coil swap
- ECU reman
- tested for air/vacuum leaks
- test compression (good on both banks)
- Run-rite intake cleaning (car runs better, but still throwing codes)

 

I can't send a picture of the modules, but they're easy enough to find by following the cable coming out of the back of the cam cover. They are at the top of the firewall each side of center.

Use the wiring diagram to locate the pins for 7 and check for an open circuit. Also try swapping the modules and see if the problem travels.

 

For anyone who needs it and is reading this, I found this diagram that Graham had posted a while back (can't get the jpg to attach for some reason)

https://www.jaguarforums.com/forum/a...8-ignition.jpg

 

Update: Swapped the ignition modules + hard reset last night. Still P0307 and P1316. Those buggers were a little stubborn coming off but were ultimately quite clean.

I'm going to swap in new coil, double check the ECU repair (not sure where it was done, as it was done while the car was in storage. There should be a seal. If not, probably worth sending to ASI for a check?).

My coil cover on the offending bank has cracked tab (closest to firewall, top one), so I have an intact one coming in soon as well (probably not a big deal, but bothers me to have cracked stuff).

Need to recheck with my indie about a smoke test/ vacuum leak. The previous shop said they did, but I had issues with them, so maybe it's worth having my current trusted indie recheck. One of the tabs on the intake hose connecting to the throttle body is a bit crumbly, so maybe worth getting a fresh(er) one of those too. It looks like it'll eventually crumble off.

If nothing comes up...wiring issue?

 

Also another thing that has cropped up is that it cranks longer when cold starting after a day or so of sitting. Always starts up, but there's slight hesitation if I've left it for a day. No real hesitation if the car's already warm.

 

When you start the car turn the key on and count to 10 then start the car and see if you still have that hesitation.

 

Yeah, I've been priming it by leaving it in the on position for a few seconds before starting. Didn't really make a different. Over the weekend though, I cleaned off the throttle body and installed a new air intake hose (the old one was crumbling where one of the fasteners goes in). While I was at it, I gave the MAF sensor a quick spritz with MAF cleaner--it looked pretty clean actually, so I didn't want to mess with it too much. The throttle body was pretty dirty, though. A solid black ring. Cleaning it off helped the hard start and rough idle a bunch.

BUT...it looks like P0307 and P1316 are pending again, though car is driving smoother. You can kind of hear the burble around 2300-2700 rpm. The thing that gets me is that it's so intermittent.

A weird thing happened though--when I replaced the injectors on bank 2, I made sure (about 5 times over) that I had released pressure from the fuel rail via the schrader valve. However, with the injectors out, some fuel spurted up from the injector port on 7. And only 7, even with the others out. Could it be that something's going on with the fuel rail...???

Other than that, we might be looking at the Dave in VA all-coil replacement, or maybe faulty coil connector (weird?).

 

After you did all this work did you do a hard reset?

Gus
www.jagrepair.com

 

Of course! It has become standard practice for me to do a hard reset after changing/replacing anything.

Just drove home from the train station. It is not a kind drive for the car. about 35 degrees out and lots of traffic. Hard to average more than 10mph. However, when I scanned the car again (it has been 95 miles since the reset and the work), it did not show P0307 and P1316 pending. However, I still have P1000, so not a full drive cycle yet. I'm pretty baffled by how intermittent the misfire is.

 

 

Another brief episode of relief, followed by the issue coming back. But I wasn't expecting throttle body/maf stuff to solve a single cylinder misfire anyway.

At this point, I'm thinking there a few more things to check/try before sending it off to my trusted indie for further exploration:
- Check condition of coil connector
- check (as far as I can) the wiring--maybe a rodent got after a bit of it (I found a nest tucked behind the injectors on Bank 1 (???))
- Check ECM connectors (maybe the previous shop didn't reconnect it correctly)
- Check seal on ECM (if it was remanned, there should be a new seal on it)
- Swap in a new coil anyway, just to see if something changes

I'm not convinced that this isn't an electrical issue. Car is harder to start when cold or raining. Misfire is intermittent, and P1316 implies to me that this isn't a fuel issue (especially after swapping those injectors) but that perhaps there isn't enough spark getting to that cylinder under certain conditions (even though I've got new plug). It's possible that there's a vacuum leak somewhere, but I'll rule out the above before having my indie perform a smoke test etc.

A labor of love, I suppose.

Edit: Also, started the car up the other day after it had been sitting in the rain while I was at work. For a millisecond while cranking, the "stability control fail" message came on. But only lasted a millisecond, and the car started up. Which is part of why I'm thinking electrical. This has happened one other time, also only when the car has been sitting in the rain.

 

The problem with rain could indicate a poor ground connection somewhere. Check for a bent pin in the ECU connection and also the ignition module.

 

Brought the car to my indie, and I've handed over the detective work to him. He pulled the head. Valves looked fine. Guides were fine. Springs are hard to tell, but I'm having him replace them since we're already there. Maybe they're worn. The real issue is that there seems to be scoring on cyl 7, with "some different colored spots."

This, obviously, does not sound good. Sounds like Nikasil failure, possibly due to the bad gas that was in it. He's going to look further into it, but needless to say this is a pretty bad day. If it's nikasil, I'll just run it til it dies. Maybe I can save up for a used engine.

 

If you put it together and drive it add a can of Restore and drive the car. It has been used by many Nikasil owners.



Link https://www.restoreusa.com/index.php

 

Update: So, after a bit more exploration, the cylinder linings were not as bad as initially feared, and certainly not to the point of Nikasil failure. After removing the head, my mechanic told me that everything looked fine to the naked eye, no bent valves, no broken springs. However, when he removed the valves and springs, one of the springs seemed a little shorter than the others, perhaps causing that valve to close a little slow. After replacing the springs, lapping the valves, and replacing a few other incidentals along the way (including head gasket), he put the car back together and has reported that the car is running much smoother, and is idling consistently through all gears (and PRND, whereas previously it was rougher in park but near normal in drive).

They're going to do a bit more road testing next weekend, but fingers crossed!

 

One of the valve springs was shorter than the others? Interesting. If this problem persists, I suggest removing the spark plug and examining it for evidence of a lack of fuel or ignition. And a compression check after that.