I just moved from northern California to Salt Lake City and once here a few months, I had my 100,000 mile service done on my 2005 XType. The car was fine until the 100,000 mile service.

Now, whenever I drive the car, it intermittently (and getting more often) seems to "miss" when I'm accelerating - be it on city streets or on the highway. It seems to mostly go away once I hit a steady speed, but if I slow down or speed up, the engine seems to hiccup again.

I took it back to the mechanic twice and explained the problem. The second time they kept it a week and supposedly drove it but the car didn't act up for them. They also said nothing is showing up on the computer. They did make sure all the spark plugs were firing correctly.

So, I'm at a loss. I don't know a whole lot about my car, sad to say, but I'm thinking something went wrong during that 100k service.

What could it be? Any suggestions?

Thanks.

 

Was there a fuel filter change logged on your 100k service invoice? If not that'd be my first move. Is your battery in top condition? Since there are no OBD codes showing the only other thing I'd recommend is to run a bottle of fuel injector cleaner (Techron, Sea Foam, etc.) in next couple of fill-ups and see if that helps.

 

scluvsrain, did they gap the plugs correctly. There is bad gap info out there and if they used their books, they may not have the correct gap information. After that, I would be looking at the plastic tubes that run under the intake (green and white as I remember, possibly the white one is orange). With age, these get brittle and can break just by moving them. After that, I would be looking at the plug wells for signs of oil.

But, like I started this with, from the sounds of things, they have the plug gap wrong and that is causing what you are seeing.

 

I will check on these things. Thank you for these ideas.

After I posted my query, I read an older thread that had lots of discussion about lambda 02 and coils. Not sure if the symptoms are the same or not, like I said in my original post, I'm not very smart about the workings of cars. I have taken excellent care of my car, however - it gets serviced timely, and I don't abuse it.

 

An oxygen sensor (lambda) problem will generate an OBD code and turn on the Check Engine Light (aka CEL). And there are four of these sensors - two for each bank of cylinders. OBDII was mandated on all modern (1996-on) cars, so you'll see these issues for any auto. Oxygen sensors work in conjunction with the catalytic converters, which are very expensive parts. Likewise, a misfire caused by a bad spark plug is going to also generate a code. Since your mechanic says no codes present I think your symptom is something else.

 

scluvsrain, something you can try to help with the diagnosis is to find a long uphill spot that you can accelerate on (say a long uphill run on a highway). Go as slow as you can and then give the car lots of gas to make it go into its missing. Maintain it for as long as possible. What this is doing is giving the computer time to figure out which cylinders are having issues. Things like a misfire require so many occurrences within a period of time. By doing the long acceleration, you are giving the computer the time and the uphill makes the car work that much harder for that much longer. then you may get the CEL to turn on which will then give you a code to narrow things down.

 

scluvrain: Just spit balling.......

Check the electrical connector at the bottom of the throttle body. It becomes brittle with age and engine heat - not a problem until someone messes with it, e.g., during 100K mile service. If the connector is compromised, the intermittent connection can cause the symptoms you're experiencing. Some people epoxy the brittle plug, other's replace it.

This link has more info: https://www.jaguarforums.com/forum/x...smashed-99605/

 

If that causes it then it's likely one or more bad coils.

If the MIL flashes STOP doing it (means cat conv damage).

 

Now that the busy holiday is over, I've got an appointment with the mechanic on Friday. I'll be armed with all of these suggestions and hope that they can find and fix the problem once and for all.

 

I'm with JagV8 here, note the CEL will only be set when a code is flagged up on 2 successive drives when the fault comes up both times, so if you can get the car to misfire under load, turn the car off and then start again and do the same thing if possible, then the CEL should light.

As JagV8 says if the CEL flashes this shows CAT damage occurring, take your foot off the gas and it should stop flashind, again if it happens on 2 successive drives the CEL will set on.

 

I was wonder by the head line of thread; How can an engine be missing while the car was running? Where the engine goes? LOL just like to have little laugh.

 

You need to replace the upper and lower intake manifold gaskets (very simple job.) Also, the throttle body can be cleaned. If it was an issue with the throttle body position sensor plug then the vehicle wouldn't accelerate at all.

 

bahahahaha. That's a good one.

 

So, I took the car back to the mechanic and he checked all of the stuff that y'all suggested - everything was fine. However, he did discover a clamp missing on a hose that was letting in air. He fixed that and said he hoped that might be the issue.

It's driving better but still riding "rough." May have to break down and take it to the local Jag dealer, of whom I have no history or experience with, having just moved here.

 

scluvsrain, never got an answer on the fuel filter. When's the last time it was changed? Sounds like you're not a DIYer, so I think you could this done easily at a local fast lube for about $50. I'd do that and some fuel injector cleaner in the tank (Techron, Sea Foam or the like) and see if that helps before going to the dealership. And by the way, make sure your engine air filter is clean. Simple replacement if it's not.

 

Yes, the fuel filter was changed and air filter cleaned.

And yes, I am soooo not a DIYer when it comes to cars. I can do other amazing things in life, however....I crochet beautiful blankets, I can cook fantastic "just like home" meals, and make a bad-*** cosmos!!

 

Well, I'd try a bottle of fuel injector cleaner then and see if there's any improvement. If you take the car to dealer or an independent with no codes showing, they'll dive into it but be prepared for the bill.

 

I knew someone who had one of those funny little German sports cars and, when they looked in the front, the engine was missing. Not a big problem, though, as they found there was a spare one in the back !

 

Ha, ha,ha. Lucky they have a spare engine, I'try to put it in the front port some time.: