UK Car Repair: Idle adjustment, jaguar xjs, speed unit

Question
1994 Jaguar XJS stright six engine....where/how do I adjust the idle speed? Thanks!

Answer
Ordinarily you would need a diagnostic tool, but try this; With the engine at normal running temp; switch off the engine, then switch it back on -do not go to the start position-. Disconnect the plug to the idle speed unit,-it is on the inlet mnifold between the 2nd & 3rd injectors. switch the ignition off; After 15 seconds minimum reconnect the plug. Go through this process two more times BUT do not reconnect the idle unit the last time.  Now start the engine and check the idle speed, it should be 550 to 600 rpm, if not adjust it with the screw on the idle unit.  Finally switch off the engine, reconnect the idle unit plug then start again, the idle should now be 650 to 800 rpm