Ktm Scott here in beautiful (steaming hot) San Antonio. My 99 xk8 is now letting me down! I have had a constant reduced performance every other morning . Before the car is fully warmed up it goes to reduced performance for about 1 mile then back to perfect till next morning.
Now it hit me with engine protection mode (limp mode) and I was able to drive home at 10 mph .
bought a code reader and got these codes.
P1384
P1000
P0171
P0174
P0300
P0310
P1316
P0010
recorded all these codes then cleared all. Test drive and ran better than it has in the last 5000 miles.
made it to work(almost) 19 miles freeway) and again dropped into limp mode again.
pulled code P0121
had a new fuel filter so I installed that. Will see if I make it home tonight.
recently I have noticed a lot of oil coming in to my air intake from valve cover breather on r/ h side just above the mass air flow.
Have been reading up and I think my nest step is to clean the mass air flow sensor then TPS . I just changed fuel filter today . Run some injector cleaner in the fuel . Pull and clean all electrical connections around Throttle body.
i have also noticed a small oil leaK on the r/h valve cover where the vvt goes thru and I believe I have read that that can cause lean condition? I guess I’ll change out valve cover baskets and new plugs.
Any other suggestions out there?
when running the car is great, no audible misfires etc... fresh oil and filter , all new cooling system hoses w/pump expansion tank ect...typically runs great engine reads good temp , oil pressure and voltage !
thanks in advance!

 

P0171 and P0174 likely mean air leaks. You can go around checking and replacing stuff, but the best is to do a smoke test (inject low pressure smoke in the intake to locate all the leaks). The VVT seals are definitely a good start (if you see oil, there is likely air going in, too), then you can continue with all the dried out o-rings to all the connectors around the throttle body (plus dip stick). Check the under-side of the intake tube, too, especially the accordion part. Take a hard look at the EGR tube if you have one (accordion part cracks). See if you can read the fuel trims for more clues.

You can look up smoke tester for more information. You can have it done, buy a tester or even make one at home.

Best of luck, keep us posted.

 

^^ What he said....

 

No EGR on the 99 XK8.

P0121 was addressed in a TSB.

My 2001 XJ8 kept flagging lean codes BOTH banks. I tried many things but I finally replaced the MAFS with a WALKER unit and the fault was gone.

bob

 

Hows your battery?

 

Looking into the current code shows throttle pedal position sensor. ...
pulled and cleaned out the intake snorkel to throttle body. Clean now with no leaks or cracks. Will clean mas at home. If I make it!
pulled the electrical connection to the left and right side of therottle body tps ect... and cleaned all dirt and now I’m back to normal with no current codes . Now I’m going to try to get home.
When I pulled the connection on the left hand side of throttle body the plastic housing crumbled in my fingers( great!!) but I managed to get it un plugged and back in !
Are the plastic housings available? I have the same problem with basically every elec plug on the engine!
ill keep you posted.

 

Oil in the intake snorkel often means that the Part Load Breather is blocked, something to check.

 

Made it home with no faults or codes. 19 miles freeway and stop and go!
cleaning the MAS now.

 

Cleaned MAS and did a test drive this morn. Drove around 40 miles freeway and some stop and go. Car runs great with no codes but for the insesant automatic stability control fail message . That’s seems to be my only glitch.
keep you posted.