Hi all!
so ive recently finished up a head gasket replacement on my 1986 Series 3 XJ6 and am happy to report all has gone incredibly well.

fixing the Head Gasket has really made me want to get this car tuned up nicely as I can finally see the potential.

during the process I found several sources of exhaust and intake leaks and now ive finally seen how these cars are INTENDED to run. Smooth and without the entire engine shaking back and fourth!

on cold start I sit at around 900 rpm (in park) and feel very little vibration, however after it warms up the idle increases to around 1100 rpm and gets SLIGHTLY rough. it doesn't sputter out and die just sounds as if there may be a slight misfire and that the engine shakes a bit.

My current list of things to check are as follows:
The idle adjustment hex (although I dont think this is the problem)
the spacing on the butterfly valve (also an unlikely issue but I will check just incase something happened when putting it all back together)
the ignition coil (not 100% sure how to check this or if I just need a known good one to test)
and ONE known intake leak after the AFM (its the small rubber hose that sits on the drain port on the bottom of the air intake it has a hole in the bottom and needs to be replaced)

besides that im somewhat at a loss, I know rough idle is an issue on many of these carts and can be a pita to locate, ive heard the culprit can often be the AFM especially if it has previously been adjusted after the factory (which mine has not been just removed and cleaned)
any suggestions would be wonderful.

(Extra question for those who have the info:low on the intake side of the radiator there is a connector with two green wires that fit into one plastic fitting, two other green wires go into this fitting but they are individual and can be mixed up, which wire goes to which connector on the fitting as I believe I mixed these up when rebuilding.)

 

Glad it’s going well!

This thread has some good information on various sensors (o2, coolant temp, etc.), and how to check and troubleshoot them: XJ6 Series - EFI Rich Mixture (jag-lovers.org)

May be worth checking these out in additon to the work you’ve done. My o2 sensor
was dirty and/or
broken, causing hot running issues

 

The wires I think you are referring to are the connection to the thermal switch in the radiator which controls when the electrical fan turns on. Should be Light Green with Orange and Light Green with White in colour. Assuming these are the ones you mention, then it does not matter which wire goes to which terminal on the thermal switch as the switch merely makes a connection between the two wires when the temperature reaches a certain level.