About a month ago my 2000 XK8 developed a miss while driving. Codes were P0304 and P 1316. I did the following:

• Replaced the coil pack
• Installed all new spark plugs
• Changed the # 4 fuel injector

No change.

• Replaced the remaining three injectors on that bank. Still no change, the miss and the P0304 code remain.

Finally gave up and took it to my mechanic, and he's pretty much stumped also. Fuel trims are fine. No reason to suspect a burned valve, but they're going to do a compression test anyway. Anyone else run into anything similar? Perhaps a wiring problem?

 

I would check the wiring, make sure there's good connection to the coil pack on the mail & female connection, and anywhere else. Kind of trivial but make sure you're replacing the right pack too:


Try verifying that the coil pack is igniting. Look for possible vacuum leaks in the intake, and clean the MAF. Wouldn't be a bad idea to get that compression test either.

 

Next time switch coil/injector/spark plug between cylinders instead of buying useless new parts.
Install small bulb between fuel injector wires to see signal, it should blink

 

If you have not done so, maybe clean the coil electrical connector, and plug to coil spring/contact, with contact cleaner (and throttle body connectors for luck)
That worked for me on my '01 XK8 after a recent misfire on B2 that developed immediately after I had put a new coil in B2 (due to misfires/contagion on the A1 B2 B3 A4 group)

 

I have seen posts about ECU problems on the early cars causing issues like this. I wouldn't jump to conclusions, but it is a possibility.

 

Thanks for all of the suggestions. Unfortunately, a belated compression test found 0 psi in that cylinder; not the news I was hoping for. The mechanic noted that the cylinder was badly carboned-up (likely from oil burned due to the bad valve seals), leading him to believe that one of the exhaust valves might be held open by a chunk of that debris, and he plans to run an aggressive cleaner through the engine on Monday to see if it will free up that valve (if that is even the problem). Failing that, looks like a $$$ valve job in my future which should cure the oil smoke on start-up.

In another life, back in the 70's, I had a repair shop specializing in Jaguars (which were far less complex back then). Unfortunately, I just turned 77 and have neither the motivation nor the time to tackle this myself (sigh).

 

Max, fingers crossed that the cleaning fixes it. Let us know how you do, hopefully good news.

John

 

Unfortunately not good news. The car is still running on 7 cylinders and it looks like major surgery (a valve job) is going to be required as soon as I can determine a competent (and reasonably-priced) surgeon. My best guess on cost is $ 3,000-$ 3,500. If the rest of the car weren't in such excellent condition, it would have been a much harder decision (we've all been there).

 

Have you tried the rope trick?

 

Thanks for the suggestion. I'm familiar with the rope trick that consists of pushing thin rope through the spark plug hole to prevent the valve from dropping in when the valve springs are removed. Is this what you're referring to? Not sure how this addresses the problem since I'm not entirely sure what the problem is. A stuck valve is a possibility, but it might be something else. The real problem is that while I have taken apart and rebuilt many engines over the course of my life, I'm now 77 and frankly lack the motivation to start tearing the heads off the engine in what will likely become a long-term project. Not that I have money to burn, but I'd like to drive the car again in the near term.

 

I feel for you. I don't think I'd tackle that job now, and I'm only 63 ! I don't recall seeing many issues like this with the Jag V8 - I mean burned valves, or stuck valves. If you get a chance to take any photos, it would be interesting to know what happened. TIA, and best wishes for a quick recovery (or relatively).

 

Having a similar issue with my 97 (P0307 and P1316), but how bad is your miss? Mine is fine under load, but idle's a bit rough. Just wondering to see if I should brace myself...

 

I would look into an engine swap for that kind of repair cost.

 

Sorry to hear that EnjoyEverySandwich (I'm also a Zevon fan!). The miss in my car is also most noticeable at idle and seems to smooth-out somewhat with increased rpm's. Unfortunately, "Restricted Performance" is showing on the dashboard, so the engine cuts out when it hits 3,000 rpm and I haven't been able find out how it runs above that.. Have you done a compression test on that cylinder? That will tell you more than you might want to know. The engine in my car is pretty carboned-up due to burning oil from bad valve seals which may have contributed to or caused the problem; zero compression in cylinder # 4. I've never heard of cylinder with 0 compression being temporarily "cured" at higher rpm's. Hopefully, your problem might be something more mundane, like a bad coil pack or injector.

As far as swapping in another engine, finding a good used engine and installing it probably wouldn't be that much cheaper in the long run. The engine in my car only has 70,000 miles on it (at least that's what the paperwork says), and I doubt that I could find a used engine of this vintage with similar or less mileage.

 

Ah, yeah. Compression's fine. Coils are good (swapped and the misfire didn't move). Seems for me like a combo of somewhat clogged injector and bad a carboned up valve not being able to close all the way or something. I had bad (9mo old) gas in the car that gummed things up a bit, but fresh fuel and techron almost completely eliminated the rough idle, and it's completely smooth under any sort of rpm. After 192 miles, same codes returned. Repeated the fuel/techron thing. Car ran great, but codes returned after 370 miles. So I'm thinking the injectors were definitely some of the issue, but not the whole issue. Aside from a slightly burbly idle now, the car feels pretty much normal. I got the "poor performance" message but never actually "restricted performance" with this issue.

With yours, I wonder if possibly the fuel injector connector might be damaged or faulty? or maybe the wiring therein?

 

Actually, when the car is running, can you hear the injector squirting? You can get a long screwdriver and touch it to the injector area and put your ear up against it to hear a ticking (or not, if the injector isn't squirting)

 

I would try to get someone with a smoke machine and borescope before I did anything. When you hear hoof beats, think horses, not zebras.

 

The injectors were already changed out as well as the coil packs. Engine was checked for vacuum leaks with a smoke machine. The only thing that hasn't been done is to try a borescope to check out the interior of the cylinder visually. Interestingly enough, I cleared all of the codes and ran the engine. The miss is still evident at idle, but becomes less so as the rpm's increase. At around 2,500 rpm the engine sounds almost normal and actually starts to run faster on its own. I'm guessing that one of the valves is not all of the way closed which is why I get 0 compression at idle. As the engine speed picks up, the cylinder doesn't have a chance to bleed down all of the way and starts to fire, which is why the rpm's increase. Seems more and more likely that a piece of carbon on a valve seat isn't allowing the valve close. Just a guess on my part. I'll try running some Techron through it and see if anything changes.

 

EnjoyEverySandwich, I have some rebuilt and matched injectors. You're welcome to two of them. PM me and I'll send them to you.

 

Thanks, Max. I actually just got a set of 8 used off of another 97 xk8 (super cheap..suspiciously cheap), so I may see how that goes first. No guarantee necessarily that they're gonna be any better, but worth a shot. May swap out my air filter while I'm at it, just cause it'll be easy and I'm not sure when it was last done. I'll be in touch if I need those injectors though!