So i noticed my car getting worse fuel milage and felt what i thought was my transmission popping. A few weeks goes by and it gets worse.. Car is getting c combined fuel milage of 12mpg!

i decide to change out the plugs to see if it would help. This is what i did and the outcome,

1 remove air filter first and check or replace it.
2 take off air filter cover and spray inside the cover some carb cleaner to clean off the mass airflow sensor. DO NOT touch the little wire on the sensor!
3 remove air intake tube and check the throttle plate. Mine was BLACK! get an approved throttle body cleaner and plastic tooth brush and clean the throttle bode assembly.

4 reinstall the air filter assembly and start the car. Its gonna take a few to start due to all the cleaners being in the throttle body. Take her for a blast to clean out any left over residue from the cleaners.

5 remove air cleaner assembly again, remove coil covers and remove coils.

6 i removed one plug at a time to find that they were originals still! Gapped at almost 90!

7 i installed the new boch iridium plugs properly gapped at 38 according to jaguar dealer

8 reinstall coils being careful of the wiring, it feels brittle.

9 assemble the rest of the coil covers and air filter assembly

10 clear codes or do a hard reboot.

11 reset all trip and fuel computers

12 take her for a drive and feel the smooth raw power and. Enjoy watching your mpg increase to 18 mpg and climbing!!!

Just figured id write this up as my work for the day on my kitty... Cheers!

 

It must feel great to see such a big increase in your mpg

 

Sure does!