Hi,
I apologise as I know there are so many posts on these error codes but we have read all posts we found, and tried many things (see below) but still have problems.
If we reset the codes the car will start and drive fine.
If we restart the car when warm the lights come on almost immediately. If left to cool down it will be fine
We have checked all hoses / pipes and have changed thxj8e MAF sensor.
We have sprayed carb cleaner all around the intake hoses and manifold but no change in tick over
Any suggestions greatly appreciated.

 

I cannot speak to the XJ series, but on the XK8 V8 engines, these P0171 and P0174 codes can be caused by leaking VVT (Variable Valve Timing) solenoid seals. There are two of them. They sit there and bake in the engine bay, get hard and brittle after a few years, then begin leaking both air and oil. Easy to pry off with a small flat-blade screwdriver, clean the area thoroughly, and push new seals tightly into place with the tip of a small wooden dowel (to minimize any potential seal deformation)….

 

+1

but also: read the fuel trims!

 

See if this information helps.

Link to Fuel Trims. http://www.jagrepair.com/UsingFuelTrims.htm

Gus
www.jagrepair.com

 

There is no "checking". All o-rings have to be replaced. All those Norma connectors (to and from the throttle body and both cylinder heads) have to be pulled and the o-ring changed. All tho e hard plastic pipes have to checked for cracks. Same for the dip stick. Replace the VVT seals, if you see oil leaking out, there is likely air going in (valve cover leaks?). Check both side of the accordion intake tube (top, rubbing on the hood liner AND bottom). Also, check the accordion EGR pipe if you have one (between the EGR valve by the throttle body and the exhaust manifold). Best is to do this job, one hose at a time over a period of time, and check the fuel trims during the next drive. These trims should come down and bring a lot of torque/driveability with it, too. Best of luck.

 

Welcome to the forum Lorraine Earl,

I've moved your question from X100 forum (for the XK8/XKR two door models) to the X350 forum (for the XJ8 four door models from 2004). This is the place to post technical questions about your model.

As the problem is specifically engine TEMPERATURE related, my suspicion is that the ECTS (Engine Coolant Temperarture Sensor) is faulty and sending an incorrect signal to the ECM (Engine Control Module) when the engine is up to temperature.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham