Engine check light on and at idle the engine slowly starts drooping below 500-600 revs and shudders, just started today any ideas

If this is a XK8 jaguar then its not that complicated for this year ,firstly check the fuel pressure manualy with a gauge in case the pressure is low ,as for a shudder from your description then iam sorry i would need a drive to know whats wrong or at least to get a feel of whats happening

start with a compression test to determine if there is a weak cylinder or imbalance . the stalling could be fuel related... check pressure and change the fuel filter. more info is needed...... lots of vacuum lines and emissions controls, are the all there? is there a vacuum leak somewhere like the intake, pcv, throttle body or plastic tee?

If one of the engine components is acting up, you should get a check engine light and have codes for the components. If the light is not coming on, it could be a suspension or mechanical problem.
Low fuel pressure could also do it.

could be a falling cam sensor or O2 sensor, O2 sensors don't like being cold as it takes longer to heat up and ecu reads it as a fault. cam sensor these fail more when they get hot. dirty MAF/MAP sensor can also affect the engine.

Hello! You have symptoms that point to incorrect fuel pressure.
First have the fuel pressure tested as follows; #1...engine running at idle: 13- 20 psi. #2...key on engine off: 23-30 psi. If pressure is incorrect change the fuel pump.

Does the engine "surge" at idle? If so, check the "fuel injection pressure regulator idle air control valve". Apply a vacuum to it; If fuel flows it is not the problem.


Guru.............saailer




I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

check alternator and the battery.

Drive it to Autozone or similar place and ask them to scan the car because the "check engine light is on". Most likely it will be a TPS switch. In area of $30 for part. It takes about 20 minutes to do. Most of time spent getting to part. But see what scan shows.

check automatic idle speed motor if equipped.

you need to have the fuel pressure checked

have your fuel system vacuumed out our excursion did it as well the injectors are not at fault it is the fuel lines