I have a 2002 XJR that has 150k miles on it. I had been driving the car for the past week or so and it ran perfectly fine. Yesterday, the car's fuel level got low enough that the fuel light came on, so I stopped to fill the car up. After leaving the gas station, I drove the car for maybe 5 miles at most and it seemed to still be running fine. I stopped at a red light and noticed the engine was idling rough. When I got home, I pulled the codes and only had a p0300 code. After giving it some time, I restarted the car, shut it off again and pulled the codes again. This time I had p0301 and p0304 in addition to the p0300. I replaced spark plugs on all cylinders with new NGK BKR6EIX-11P Iridium spark plugs and also swapped out the coil packs on cylinders 1 and 4 with new ones, cleared the codes and started the car again, but the problem was still there and the car had codes for p1313, p1314, and codes for misfires on all cylinders. After checking battery and electrical connections then and restarting the car, I'm now I'm getting p1313 with codes for misfires on all cylinders in bank 1.

Where should I start? Any help would be greatly appreciated.

Brian

 

After starting the car today and checking the codes, I'm now getting p0300, p0301, p0302, p0303, and p0304. I'm still not sure what to do. In addition to everything mentioned in the original post such as changing plugs and coils, I've also changed the fuel filter and did my best to inspect the tensioners on bank one. The car has the metal tensioners with plastic at the points where they connect with the chains. The tensioners looked fine and there seemed to be almost no play in the chain, so I'm not sure if that's a good thing or not. Still completely confused about this problem.

 

Do the flats on the cams line up?

 

Yes, the flats on the cams are lined up in bank 1. I haven't checked the other side yet since I don't have codes for the other bank.

 

I started getting that on different X.308 it’s might get it low on fuel then go fill up and have a rough idle I never pulled the codes I just dumped in a fuel additive injector cleaner that seems to help

 

You could start by clearing the codes with the engine off, swap all 8 coils from one bank to the other and then restart it and see if the misfiring moves with the coils. Gotta start somewhere.

 

I can give that a shot, but as of now, all of the spark plugs have been replaced with new NGK spark plugs and all of the coils have been swapped out for new Beck Arnley coils.

I'll try adding a fuel additive and letting it run for a bit to see if this clears things up.

Thanks for the suggestions, y'all!

 

After adding a Royal Purple fuel additive and letting the car run for a bit, I'm now getting p0300 along with p0301 - p0308, so it's back to showing misfires on all 8 cylinders.

 

Mine took a bit of time..driveling..I use cheep stp additive

 

Did your car also have restricted performance and the blinking check engine light? When I let mine idle, it doesn't show restricted performance. After I rev the engine, the check engine light starts blinking and it goes in and out of restricted performance mode. I've been hesitant to drive it because of that.

 

No it never went into restricted performance. But I have had that like many of times as I have 11 of these things xj8s... do you have a compression gauge? To rule out any other problems the car has 150,000? It’s an easy thing and it lets you know where you’re at. Whenever I do a compression test it’s like I’m going to the Ground Zero and starting from the beginning

 

Might want to check for a vacuum leak. Dirty injectors too.
Running the fuel that low isn't a good idea either. May be unrelated but you can suck up some crap off the bottom of the tank that way and starve the injectors too.
Are all the cylinder specific misfires on the same bank?

 

I would check the fuel pressure. Could be the fuel pumps on the way out.

 

+1 Fuel pressure; might change the fuel filter. But grab a wiring diagram for the ignition system. Years ago an XK8 owner had the same issue -- everyone (watashi wa included) jumped on secondary tensioners, which is nearly always the problem -- but it wound up being a loose connection effecting all coils, maybe in the fuse box on the port fender.

 

I don't have a compression gauge yet. I was thinking about buying one this coming week to check compression since it seems like I may need to check that as well.

I was thinking that I may have a vacuum leak somewhere as well. I haven't tried cleaning the injectors yet. In the beginning, I was getting codes for misfires on all cylinders on bank one. Now, I'm getting codes for misfires on all eight cylinders.

I checked the fuel pressure yesterday and thankfully, the pressure is good. As soon as I switched the ignition on, the gauge showed my pressure was at 41 psi. I'm happy about that. I have a 2001 XJR as well and replacing the fuel pumps was the first job I ever did on that car. Maybe it was because I was still new to working on Jags at that point, but I just remember that job being a major PITA, so I'm happy I don't have to do that again as of now!

I changed the fuel filter earlier this week, but still saw no change. Thanks for the tip! I downloaded the wiring diagram and will go out to the garage and start checking connections and relays as soon as it cools down a bit. I'm in the Phoenix metro area and my garage temp is 106 right now! I did find a post that mentioned a "tree" of connections that is behind the engine. According to the poster, some of those connections are for the injectors. Do you know where these connections are located? I've looked a couple times and the only connections I see seem to be for the 02 sensors.

 

Go over to the XK8 site and do a search; I think you have a loose connection . .

 

I wouldn't rule out clogged/malfunctioning cats. Especially with the high mileage. The fact is started on 1 bank only lends to this possibility. Then the other went?
I would rule it out before driving it much more. Cats can destroy an engine real quick. That's why mine are going bye bye. Way more trouble than they're worth.
Does the CEL flash when this happens?
Unless there's one connection that serves all 8 injectors, a loose connection is unlikely. It has to be something that can affect all cylinders randomly or 1 bank of cylinders randomly.

 

So far, I've checked every connection that I can find and everything seems fine there. I could've missed something, though. I did find a thread in the XK8 section where someone with an XKR who had the same problem mentioned that his mechanic sealed something to stop some sort of leak. The poster referenced another link saying that the fix to his/her problem was the same as a fix found on another forum, but when I clicked the link, it was dead!!

Yes, my CEL does flash when the engine is revved. When I first noticed the problem, the car was reporting misfires on two cylinders in bank 1. After I replaced the spark plugs, coils, and the fuel filter, I cleared the codes. That's when the car started giving codes for misfires all cylinders in bank 1 and eventually gave codes for misfires on all cylinders in addition to p0300 and p1314.

I'll try briefly running the engine with the upstream O2 sensors removed to see if that clears up the problem. That should tell me if the cats are bad, right?

 

You can try that. The CEL flashing convinces me even more it's your cats. Don't drive it. The flashing CEL means engine damage is occurring.
Worse thing ever done to an engine was cats. Even when they're working right.

 

Brian, I went back and reread your post. You said the low fuel light came on and you filled it up. 5 miles later it was misfiring. You don’t think you put like E85 in it or maybe you got some bad fuel..... just some thoughts. Maybe take a fuel sample next??