My 2000 XK8 has led a pampered life and has 140K miles on the clock. Trouble free until recently. While stopped at a traffic light, the tach dropped below 500 rpm when she lapsed into a rough idle. The check engine light and "restrictive performance" message switched on. She misfired and "bucked" a few times on the slow ride home at just above 2000 rpm. DTCs: PO171, PO300, PO306, PO307, P1316 and P1642. Eventually resolved all but the intermittent PO171. Smoke tested, replaced O2 sensors, cleaned MAF, ran injector cleaners in 2 tanks of fuel, tightened every fitting, changed fuel filter, replaced one coil pack. My Jaguar Master Technician is scratching his head. Help?

 

Well, if you haven't tried it yet, you might try replacing the VVT seals in the valve covers. A few folks on here have had success with this and it's cheap and easy.

 

At this point, you need some data, in particular the short and long term fuel trims. If you don't have a tool for this, yet, get a cheap eBay ELM327 OBDII reader and an app for your phone. For a few $, you should be able to see where they stand. Check at idle for air leaks. Check with some rpm for signs of a poor air flow meter.

Remind me, is there an EGR system on a MY2000? The EGR pipe bellows are known to crack and admit unmetered air.

Best of luck, keep us posted.

 

New VVT O-ring seals cured the P0171/P0174 codes on my wife's 2006 XK8 back in late February. Whether or not yours are seeping oil as they tend to do, if they are old and brittle they may indeed be the culprit....