Hi, drive XK8 from late 1996 and have rough running engine from time to time . Only when engine temp gets from cold to normal temp. Code is P1242. But what does it mean and where is the best tip to start to fix it.
Thanks .....

 

Here is the P1242 'possible causes' from JTIS.

TPS - Throttle Position Sensor
PPS - Pedal Position Sensor
FTP - Fuel Tank Pressure

Since the first two involve replacing the Throttle Body I would suggest that you start with the FTP sensor which is associated with the evaporative control system.

You need a copy of JTIS: https://www.jaguarforums.com/forum/j...how-use-52643/

 

Do you know if the TB has been replaced by Jaguars service action S514? It appears that the TB had a problem with that MY this link might help Xclusively Jaguar - Facts and Information - For all your Jaguar needs.... Jaguar Cars, Used Cars, Classic Cars, Jaguar, Daimler, Cars For Sale, Parts, Automobilia, Accessories, Buyer's Tips, Newsletters, Information, SS & Pre-war, 1950's Sports, 1960 As for the codes I am attaching a DTC code Summaries http://www.gusglikas.com/images/Auto...%201997-99.pdf You could remove and clean the connectors to the TB first and see if that helps before replacement. As a note you can purchase a rebuilt unit that will work just fine. I hope this helps!

 

Here a short status report:

To test point: I cleaned all connectors around the TPS and the FTP on top of fuel tank. I also checked wiring and vacuum hoses. The hose who fits to the black round canister on top of the throttle boddy had a very loose fit. Thanks for the JTIS info.

To GUS : I cleaned connectors. Thanks for the other info. I do not know if car went under a PIP. But since SN is very young , he may only got an soft ware update.

I fueled the tank to 100% , and with all the cleaning , up to now no problem. Will try to repeat the problem from full tank to low tank. Will report back later.

Thanks you all , very good forum here in US.

 

Evap tests typically only run when the tank is between 1/4 and 3/4 full.

 

Beav, does this mean when problem comes back with tank between 1/4 and 3/4 the problem is related to the EVAPORATOR System ? ...now i will try to get the tank volume in the middle and test a few times from cold to warm engine temp .
Thanks.