Hello everyone,
I have a 2008 Jaguar SV8 4.2 supercharged with around 90 000 km.

I have this issue when using the paddle shifters.

When i go into first gear and accelerate around ½ or ¾ of the throttle, my rpms jumps between 2000 and 4500 rpm, it makes 500 rpm jumps resulting in a more than jumpy acceleration.

What could it be? Im very worried!

By the way, i thought it was may some wheelspin but it isnt.. i dont know what to do

 

I would be looking at your torque converter.. Granted, if it is only doing it with the paddle shifters, then I would be looking at the paddles themselves and potentially recommending removing the paddles from the steering wheel and squirting some electronic/contact cleaner into the switches on the inside. You can prove the switch aspect by getting up in RPM and maintaining an RPM and then wiggling the switch side to side to see if it will cause the RPMs to jump (the computer thinking you are looking at shifting the car and starts to prepare the tranny for a shift). Keep in mind that the car does a lot with the fly by wire throttle set ups and shifting the car. To make the shift a bit smoother, when you tell the car to shift, it will actually back off on the throttle (even though your foot is in the same position), it then bumps up the pressure in the tranny, shifts the gear to the next one, then lowers the pressure, and then returns the throttle to where it was. It is doing all of this in a matter of a split second. But, being in first gear, your torque converter is not going to be locked up yet and this can cause RPM jumps. Granted, if this is happening when not using the paddle shifters, then I would be looking at the torque converter as that is more than likely getting some sort of command and it is causing it to slip a little more than normal, leading to the higher RPM jumps.