I read earlier posts on engine shaking. Maybe you can give me an advice. My car is Jaguar s type 2001 3L. In my case, the funny thing is that when the weather is cold or cool, my car does not shake on idle and no resitricted performance happens. But when the weather gets warmer or hot, it starts shaking like crazy, even if the gear is in neutral position. It seems like it depends on air temp or what? I have new spark plugs and it does not eliminate the problem.
What could be the problem?

I repeat. When the weather is cold, the car runs great.

Any idea?

 

Start by watching fuel trims. They can reveal various faults are present/absent.

 

+1 on reading fuel trims, both short term and long term.

You do not state the number of kilometres/miles on the vehicle, but given its age, you may have failing ignition coil(s) that can produce similar symptoms.

 

The car has 150 000 km and has original ignition coils (never replaced). Still, I think it is somehow connected to air intake; there could be a leak or a hole in a rubber pipe and air does not flow gradually and during cold weather it is not that crucial, maybe, and that is why the engine runs without jerking when I am idling. This is just my theory). Somehow, this whole thing is tied to air temp outside, so my first thought was - AIR FLOW. In cold weather the car runs perfect, no jerking, speeds up well, no complains. I should probably start by checking air pipes for holes. And also, air filter is fine as well.

 

no . do what was asked of you above , two posts say check fuel trims ! learn how to if you don't know , and this will tell you if you need to check any pipes or gaskets for vacuum leaks! then if necessary you start looking for your leak if any present , these guys have pointed you toward the first step of actually finding a fault instead of following a hunch .
big time saver ! get a scanner and do the test .

 

Ok. Thanks. I will do that first.

 

You need to do ALL the maintenance that the car needs. Your 6 cylinder has a well known list of problems. Lucky for you they are not too expensive and you can DIY them. But fix them all at once or you will be removing the intake multiple times.

Remove the intake and replace ALL coils and plugs, intake gaskets and read up on the vacuum elbows and IMT O-rings. These are all well known problems too.

Then service the transmission with filter and fluid change. Be sure the fluid level is correct! It's not easy and it MUST be done as per the factory directions.

After the above clear all codes and drive the car to see if anything comes back.
.
.
.

 

Changing ignition coils got rid of jerking problem

 

Great that you got it fixed. And a thumbs up for reporting back!
.
.
.

 

Forgot to mention. I also cleaned a device which controls air coming in for mixture, forgot how they call it....maybe "shutter". It looks like a flap which turns closing and opening inside air duct and regulates amount of air. I cleaned it with special fluid.
Dont know which fix did the job....this one or changing coils, but the car runs without restricted movement and jerking.