Xjs 4.0L Engine hesitation.

[Graham C]

Hi Everyone.

I've had a long standing problem with my 1992 4.0L Xjs.

When the car has been run to full engine temperature, the left for say 90 mins, shortly after moving off the engine has a hesitation as if stopping for a few seconds.

It feels like fuel starvation. However a new pump and filter have been fitted along with leads, dizzy, rotor arm etc.

The car runs beautifully after this short hiccup. However it could happen causing a dangerous situation.

The engine has many sensors, many of which have been replaced.

Is there a component I've missed to do with 'warm starting'?

Any help would be appreciated.

Many thanks.

[Jaguar Owners Club]

I wonder if it is the coolant temperature sensor which is giving a false signal which in turn would control the ignition and injection and this is causing it.

You can test it with a cheap scanner which shows the engine temperature as it warms up.

[Graham C]

Thank you very much for your reply.

I think I had that sensor changed, but that doesn't mean it's not faulty.

I'll look into it.🤔

[JOE-DOT-COM]

hi

Ideally you want a logger on it to monitor all the sensors

on more modern Jaguar its quite easy and cheap to do, but dont know if there compatible with a 1992 car

Jaguar wds/ids should do it, would have to be a really early version, logging sensors then looking at the data should tell you whats causing it,

favorite items would be maf, ignition, timing or leaky injector

also have a look here http://www.jagrepair.com/ at the xjs technical service bulletins fault might be a common fault

cheers

Joe

[Graham C]

Sorry Joe.

I've just realised I didn't reply to thank you for this invaluable information.

Cheers.