So. Where to begin.

I just dropped my XJL Supercharged off to the dealer again yesterday. I've had a persistent engine vibration occurring (I posted about it here: https://www.jaguarforums.com/forum/x...lancer-175385/ ) right at about 2,000 - 2,200 rpms. The car idles rough and almost seems to stutter intermittently (it's done this since I've owned it); it almost sounds like it's low on oil. Thanks to our trusty e-dipstick, I can tell you it's certainly full. I had the throttle body cleaned 18 months ago to no avail. Needless to say, the car doesn't run "right" and it's gotten worse over the last 3 months or so. According to an OBD-II scan this week, my number 7 cylinder is misfiring continuously.

I took it in to the dealer in December and in January for the same issue. Their fixes were a new prop-shaft and to replace the high pressure fuel pump and fuel lines. The vibration can be felt through the chassis and is also accompanied by a "knock" at idle as well (which you can hear in the video in the link above).

It's been 3 weeks since I got it back from changing out the fuel pump - no change. Long story short, I take it back in yesterday, and from the moment they start the vehicle up, my service writer says "Hm, that idle doesn't sound good at all. Sounds like something's wrong with your motor." My response was basically "Of course it sounds like it's the motor! It's the same sound I had you listen to the last two times I brought it in!" "Is it low on oil?" "No, especially considering you (the dealer) topped it off 3 weeks ago." "We show it hasn't been changed here in a while. That's probably why." "I do all my own maintenance, and have the records and receipts to prove I change it every 6 months or 7,500 miles." "Do you suck out the throttle body?" "Yep." "Well you're out of warranty now so we'll get it diagnosed, but it sounds like something is definitely wrong with your engine."

So that's where I'm at. I've read the threads on injectors getting stuck and possible carbon buildup on the back of the valves. Can that cause a misfire and vibration at certain rpms? Just stumped at this point and frustrated that it sounds like this is going to be a major repair right outside of the warranty period, especially since they've been trying to figure it out since December.

Here's to hoping I don't need a new engine!

 

a6kmita, if you took the car into them for a problem while the car was under warrantee and they have still not fixed it, then it should still be fixed under warrantee (even if the car is now out of warrantee). The dealership still has not "fixed the problem". So, the problem was found in time to be covered by the dealership.

As for why you are getting a misfire on cylinder #7, my experience has been that the coils are the first place to start. A quick check that you can do is to look at the top of each coil. What you are looking for is a white line either in the center of the coil or running around the edge. This would be an indication that the epoxy top has failed and is letting water get inside the coil, leading to it not being able to spark properly, leading to the misfire. After that, I would pull the coil and look down inside the plug well. Another common issue I have seen with other models is getting water/oil into the plug well, leading to the coil being able to spark straight to the engine vice through the spark plug.

Just to ask a silly question, do you notice this being a bigger problem when it is raining outside and/or having recently run through a puddle/having the car washed? This would again point back to a bad coil.

 

Don't know whether this would apply in your case or not, but I had a head gasket leak that was running down over a coil and causing a misfire. My dealer diagnosed it properly and repaired it on the first try, while it was still under warranty. This failure occurred at approximately 47,000 miles. This may or may not be your problem but we have essentially the same car so thought it would be worth mentioning. Good luck!

Dwayne

 

Thermo, Dwayne, thanks for your replies. The dealer called this morning and said that they don't suspect any issues with the coil packs or the ignition system (whew!). I asked them if they saw anything related to what you said, Thermo, and they said they didn't. They said it's likely that the injectors are clogged/plugged and recommended a full flush and service of the system. They're confident that should fix it. Should be done today or tomorrow. I'm hoping that does the trick!