I have a 1999 3.0 V6 (Auto) that has what feels like a misfire from 2000 rpm under light throttle. It feels like a fairly vigorous shudder when it occurs, if I floor the throttle the car revs out of the "misfire" but feels really hesitant as the revs rise to redline. It also has an intermittent little surges at idle every 10 - 20 seconds

When the "misfire" is apparent the MIL flashes. Spark plugs look fine and I cannot detect any obvious vacuum leaks.

Connected a OBD scanner to the car and took it for a drive, I can readily recreate the fault conditions, slow, steady accel from around 1700rpm... and when the fault occurred MIL flashed but no DTCs were stored.

Pulled over and looked at the OBD dashboard on my Laptop... noticed when engine off (and ignition on) the throttle position was showing at 13% with the throttle closed. Floored pedal and it went to 79.9% and no higher. Could this be a TPS fault, rather than coils which was my first thought?

Any advice and guidance from you learned folks will be very much appreciated.

 

Stop doing it as flashing MIL = cats being damaged.

There are dozens of similar posts, with fixes, so do some reading using Search.

 

Yep start here:
https://www.jaguarforums.com/forum/s...ics-faq-52720/