Unfortunately I didn't have this checked when I just brought my car in for a speed sensor replacement with a new mechanic I found.

At idle the car seems to shudder more often now than before. There are no misfire codes and the mechanic confirmed this as I mentioned this issue after picking up my car.

When I accelerate slowly the car seems to lag, however if I accelerate hard, I don't see this happening.

I had the spark plugs replaced over two years ago when I first purchased the car.

I had the car serviced by the dealership at 65K.. it cost me $1,800 plus replacement of the steering sensor which of course caused the DSC failure as well after my mechanic replaced the speed sensor on the left wheel, but couldn't flash it. So I had to bring it into the dealership.

Thanks for any ideas.
I did see this thread but haven't checked the spark plugs yet.
Do you know if they change the fuel filter when doing a 65K service?
I'm also wondering if the fuel injector system is going bad as the car when you start it sometimes doesn't catch fast, some times it does other times it catches but at a short low lag.

https://www.jaguarforums.com/forum/s...eration-59588/

Any ideas?
Thanks experts!

 

Sounds something engine-related but most unlikely spark plugs. Also probably not injectors.

Air leak, coil(s), O2 sensor(s), etc are far more likely.

Here are the critical types of things involved in running a modern car OnBoardDiagnostics.com - Engine Basics

Don't assume you'll get codes. It's a bonus if you do.

 

I'm leaning towards one or possibly more than one of the coils exhibiting an intermitient misfire at idle/low speed operation - not enough of a misfire to be picked up by OBD...

Have a compitient mechanic test each coil at idle with a COP (Coil On Plug) tester at idle. Also, if there is any evidence of oil on the coil boot - this yields to leaking spark plug well gaskets - they will need to be changed out, along with new cam gaskets.

Good Luck..

 

Update.. engine light came on with the P0456 Evaporative Emmission System Leak detected (very small leak). I had this code several months ago, cleared it out as many times it's because the gas cap is not put on properly, or maybe when I get a fill up I still have the engine running. I don't think this has anything to do with the shudder and lag but more data for you guys.

 

Be aware that you could have timing chain issues too. Have the tensioners been changed or at least checked? It can destroy an engine fast if they let go! Sometimes the tensions back off and this causes changes to your timing which will affect the power.

Just something to check.
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I had a very slight misfire at idle, the car would shudder every 10 seconds or so, then one day the battery was too flat to crank it.

Bought a new battery and the misfire has gone completely and the cranking speed has doubled.

 

Abonano,
I think you're right on.. I started to change out my coils and on the second one I pulled out there was a lot of oil inside the coil boot, so the the spark well gasket is probably cracked and leaking. I'll let my mechanic do what you recommended. Change the spark well gaskets, cam gaskets and will definitely check out the timing chain tensioners for cracks. It was going to be my next step anyway.
Anyone have an idea on how many hours a mechanic will be taking to do the job?

I also had intermittent starting issues. Sometimes it would catch right away, other times it would take a bit of time. I'm thinking this could be the issue on that, but again I do have a code of 442 on the EVAP system too.

 

The incidence of a vaccume line leak on a car of this age become more problematic. You'll likely find a vaccume line leaking. Check the large vaccume line running from drivers side rear of engin running to front then to passenger crancase vent.