My 2000 S type SE has a strange rough running issue.
On initial starting she runs smoothly, when the engine gets a little warmer the idle becomes rough almost like a missfire. When she reaches running temperature the idle becomes smooth again.
Spark plugs were changed (Great Fun!!) as was the rubber elbow at the rear of the engine which was a bit perished. Neither made any difference.
I believe it is a fuel issue but don't know enough about the fuel system.
Anybody got any ideas?

 

Have you replaced the fuel filter? Cheap and pretty basic. There are DIY's both in pictures and video here in the S Type How To' section.

 

Yep, did the fuel filter no difference. Given the engine temp factor was thinking one of the sensors but which one? Goes like a train otherwise!
Thanks anyway

 

Can you get the codes?


My other guess is that it is going to be vacuum related. The tubes and hoses are prone to become very brittle over the years.


This may help:
https://www.jaguarforums.com/forum/s...ics-faq-52720/

 

If it's fuel system related, as Rick suggested, you might try running a couple bottles of Techron fuel injector cleaner in successive tankfuls. If that doesn't work, you might try to find a shop that cleans injector nozzles.

Hope that helps,

Mike

 

Sounds more like a vacuum leak or a throttle body issue. Could also be a head gasket starting to fail.


Check you coolant.

 

Agree with all above.

Our Silver car did similar after same service related work.

I simply went to the rear of the car, and WAITED for the odd running. The exhausts are not siamesed, so the L and R are seperate all the way to the tail. Put my hand over each tailpipe, and the RH had a distinct misfire. Off with the manifold again, and the 2A coil connector was just "not seated" 100%. Replugged all 3 and reassembled, sweet as.

I learnt that exhaust thing from all the years of V12's and their misfire mayhem. Simple to do.

Obviously, the Coolant Temp Sensor (CTS) could be going flaky with age by now, as you already did mention.

 

To see whether it's a vac leak you need OBD fuel trims. Hot engine, parked, at idle & again at about 2500rpm.

 

Feel stupid should have done this first it was the rubber vacuum pipe under the manifold. Running great now.

 

Running great is ... great

 

Thanks for the update a year later.