Toyota Repair: timing, fuel pressure regulator, jumper wire

Question
what should i set my timing to on my 1991 previa.  I have a manual but cannot find the magic number.  i set it to 0.  It also knocks when under load.  It also has a engine check light code 22 water temp sensor.  I know this is alot.  
I changed the; water pump, fuel pump, fuel pressure regulator, egr valve, egr modulator, vsv valve, water temp sensor three times, oil pressure sensor, O2 sensor, radiator and cap and flushed the system, the oil level sensor.  If you can't answer the code 22 problem, please help me with the timing adjusting.

Thanks Ted

Answer
set the timing to 5degrees BTDC with a jumper wire between terminals TE1 and E1 in the diagnostic check connector, if the code 22 can't be cleared there may be a prablem with the wiring between the sensor and the ECM or the ECM itself may have a malfuction. when clearing the code how long does it take to come back.