A very strange thing happened this morning. It was about -4C degrees (first time such a cold weather since I bought the car) and when I've started the engine it was acting as few cylinders are not working at all - the car was shaking very hard, the RPM was at 1100 and there was no noise at all. When I increased the RPM to more than 1500 it stabilized, but when they dropped - againg started to shake. I've read about the VVT problem, but still - the engine is working as quiet as never before. Two days ago I've changed the oil with Castrol 5W40... but I can't see any relation to this.

Anyway... I was highly surprised so I decided to turn off the engine and start it again. After that - no shaking at all. The engine was working just fine. Now I'm leaving my office, after the car was staying on the cold weather for more than 9 hours, when I've started it - it ran again quietly, but shaking the whole car.

Any ideas of what's happening?! I know that the spark plugs are not looking good at all (they all have some traces of something like burnings in the outer white ceramic side) and I'm planing to change them as soon as the new one arrives - can it be because of that?

 

Or a bad coil. Have you gotten a Check engine light yet? Hopefully you will, then you will have a good clue whazzup.

 

Nope... nothing lights up on the cluster. Tomorrow morning we expect some cold weather as well so I'm planing to catch everything on video and I'll post it for further discussions

 

Sorry for the second reply, but forgot to ask - is there a way to check the ignition coils status? I know that the previous owner have changed two of the coils, but I'm not sure if there isn't any problem with the other six.

P.S> Offtopic - sorry for being so annoying in the past few days, but here in Bulgaria we don't actually have any good experts on Jaguars so I have to do all the maintenance by myself in the garage. That's why I'm asking so much - to be sure what I'm doing before breaking apart the whole car

 

After changing all the spark plugs, cleaning the load breathers, changing the air filter and cleaning the entire air-flow system, the car seems to start very smooth even on -3 degrees.

Sometimes when the car is still cold and I drive without touching the acceleration pedal it chokes a little bit... I'm confident that it's related to some air-intake problem coming from the "home made tube" from the the part load breather, but I'll have to disassemble a few things to check it out. Any other suggestions?

 

Estilian:
No worries about being a bother- thats what forums are for. Glad it seems to be better. Good luck with it.

 

The last couple of days the weather was just fine and I almost forgot about this problem. Unfortunately today it appeared again and even worst.

It happens only when the engine is cold and the temperature outside is below -3/-5 C. When I turn on the engine, everything sounds normally - the RPM goes up to about 1300 and after 10-15 seconds it drops down to 1000 - this is the exact moment when the problems appears. The car starts shaking as some cylinders are not working. If I put to R or D the car gets even more unstable. When releasing the brake the car is not moving slightly but kicking forward and backwards... If I try to increase the RPM with the acceleration pedal nothing happens. The car barely moves and after about 5 seconds and serious stepping on the acceleration all the problems magically disappeared. After that none of the mentioned issues appeared again.

To be honest - I'm afraid to drive the car like that. Nothing lighted up on the dashboard - no check engine, no errors at all. Not even strange sound coming from the engine. 2 weeks ago I've changed the plug sparks.

Any ideas?!

P.S> As the last spark plugs I bought and put on my car were the only one available on Bulgarian market - Champion plugs, I'm afraid the problem could be because of low quality plugs That's why I just ordered set of NGK PFR5G-13E and as soon as they arrive I'll replace them.

But still... could it be just because of the plugs?! I was thinking about coils, but there's no logical explanation for me why after a warm up of the engine (or just after a rev up over 2000 RPM) the problem disappears!