As it's getting colder and colder, some strange things are bothering me. Here is a short list:

1. When I turn on the engine (it starts normally always from the first turn of the key), it immediately goes to 1400 RPM and after 5 seconds it drops to 1000-1100... but even after waiting more than 5 minutes it doesn't want get lower to normal work (less than 800). Is this normal? If I drive a little bit and then put to N or P, it drops and works perfectly fine.

2. On cold start the engine is noisier... No metal clanks or rattle... some little shakes to both sides as if someone is pulling the car from side to side. I've changed oil to 5W30, but it still sounds more rough than usual. Again - after driving for a while the engine is working in total silence.

3. As I mentioned in p.1 when the engine is cold, the RPM never drops below 1000. I always wait for about 1-2 minutes before driving, but still - when I switch to D or R, holding down the brakes, the car always makes some kind of kick. This happens only once per cold start. After that all switches or gears are very smooth. Is this normal? Only once I've tried to switch to D and immediately release the breaks - the kick was gone but I'm not sure if this harms somehow the gearbox.

4. When I enter in the city traffic I noticed that when I hold at half the brake the car runs very slowly but it shakes front and backward - very slightly but still I don't think it's normal. What could be the problem causing this?

 

With all those idle and cold start issues, the FIRST thing you need to do is to disconnect the battery and reset the car. Leave it disconnected for several minutes and reconnect. Once that is done, reassess on the next couple of cold starts and see where you are.

Good luck!

 

Unfortunately - no luck at all. I've tried to reset the car (experimenting with 3 different ways to do this) but all the mentioned problems are still appearing. Any other ideas?

 

It appears to be a single problem arising from the fast idle. The transmission is engaging roughly because it is being engaged at high rpm.

As you say that the problem was brought on by colder temperatures, you might look at the ambient temperature sensor. If the engine management system does not know what temperature it is, it does not know how to fuel the engine properly.

You can also look for vacuum leaks caused by hoses going stiff in the cold. In particular the big air intake hose.

Another possibility is a dirty MAF or a dirty throttle body. Have a look while you are having a look at the intake hose.

 

Mine does not do the weird RPM thing. Not sure what could be causing that... TPS? Mine does not like cold starts either. I've been having this weird starting issue, still do not know what is causing it. It takes it awhile to start at work when it is cold and usually takes a few tries cranking it before it finally starts. When it has been in the garage, it is fine, usually fires right up. I know what you are talking about, that "rocking" back and fourth feeling. Mine does this too, its not very pronounced. But it will do it at idle and make the passenger side seat belt buckle vibrate a little (most car owners would never notice, but I'm very particular). Our X350 does not do this, but considering how old mine is, it has an excuse. I've been in brand new Chevys that have more wobble to their engines than this Jag, so I am not overly concerned. Maybe the engine mounts are getting old, idk...

I also get an audible "click" from the drive-train when accelerating after just putting it into D. It only occurs once, and I have to push the gas to get it to happen. It is very subtle, almost sounds I ran over a large leaf.