Re: XH ignition problem
Because the XH is basically the same as an EL, you have to put the ECU into static mode so you can set the base timing. Search the forum on how to do this.
You need to bidge two pins on the diagnosis connector and then start the engine. The revs should increase to about 1500 and then die back to a steady idle. Connect the timing light to #1 pot and aim it at the crankshaft pulley and the timing mark. After about 90 seconds you should see the timing alter and then stabilise. Set your base timing to this. Caution - be patient and wait for the timing to settle. It does take a while, and it will go down in steps. I got mine wrong because I did niot wait long enough.
If you don't trick the ECU you'll never get it right because the ECU dynamically alters timing to suit engine condiitons. Oh yes, make the final check with the engine at normal temp and with all accesories off.