Hi! i started up my 2003 jaguar x-type 2.1i, and after few seconds i saw the rpms drop way down like 400-500 rpm`s and the car started shacking, and both interior and exterior lights are flickering when Idle , i started the car again and same thing happened , from 1k rpms it goes to 400-500rpms. I checked for vacuum leacks and found none, and cleaned up both IACV and trottle boddy. Any ideeas on what should i check next?

 

Hi Gabe,

I'm no expert on your model of X..but you might want to list where you are located/mileage/age of battery..and also mention if any lights or messages were noted on the dash at the time of this issue.

 

First thing to check is the battery. Make sure it is fully charged. Second remove and clean the battery cable clamps and cable ends. Check the ends of the cables and make sure they are not corroded and cracked.
The x-type electronics do not like low voltage. The cables are notorious for corroding and causing voltage loss.
If the cables, connectors and battery are all good then you need to test the alternator. Right after startup the output should go to 13.5 to 14 volts to help the battery recover from starting and then settle out around 13 volts. Any time the voltage goes below about 11 volts the gremlin's come out and wreak havoc.

 

the car has 100k miles, and the battery is almost new, about the alternator i`ll check the output today, also my check engine light came on, i used a scan tool and i got these codes:P0511, P1646, P1316, P0122 and P1632

 

I have attached the definitions for the codes you pulled. Jaguar does not have a code P0511 listed so please verify that code number. While you are there if your scanner will do it clear all codes.
With the engine and ignition off use a multi-meter and take a reading from the battery post to ground. Then from the battery clamp to ground and finally the cable wire to ground.
Your codes I still think indicate a voltage problem.