My rpms drop and move up n down wen in park if i pull up in the parking lot and put it into park the rpms will drop and sometimes stall out car will just go dead. I get a lean code that comes on and off its po171 and po174. Could i need new spark plugs and coils or something? I did them wen i first got the car which was like 20 30 thousand miles ago maybe 40 but if any has had this problem and solved it let me know

 

Look for leaks on the intakes and check all vacuum lines for breaks or cracks.

 

If nothing along the intake past the MAF has been disturbed recently, you might get away with cleaning the MAF with the CRC cleaner. It might take a few spray downs and drive cycles to see any effect. If that doesn't do it, there is a significant vacuum leak with unmetered air getting in. This engine is very prone to this as it ages with about a dozen common failure points you can see them all by searching the code on the XK XJ and S-Type forums.

On a normal car you would hear the hiss from the leak, but the ******* design of the PCV on this engine intentionally hisses loud and drowns it out. Find a good independent repair shop if you have not already and have them do a smoke test. You want to be a witness from the moment they touch your car to see where the smoke is escaping. Some fixes are very simple like some jb weld on an plastic plenum crack. Others are expensive seals or a tiny o-ring that is very hard to get to.

https://www.jaguarforums.com/forum/s...8/#post2415361

A shop can claim that the supercharger needs to be removed for this or anything in between, so trust no one. If I was dealing with this again I would get one of these, I just resent having to have so much gear just to avoid getting ripped off by all the shysters out there.


Let us know what it turned out to be!