My sincere thanks to all of you for helping me to clear my technical doubts.
My engine is 4G54, 2555 cc, year of manufacture is 1990 - No ecu - but originally with a lot of vacuum hoses.
Presently the only electrical connections is the "idle stop solenoid valve" - 2 wires - no problem for me to connect up.
Existing carb could still work - but since it is over 11 years, I have to look for spare-parts/backup carb - as such vehicle (gasoline version) are very RARE in S'pore or even in our neighbouring country - which are mainly Diesel/TDI. I have recently replaced the depression chamber - after getting technical advice from this Forum.
Also Carb is a key component which is very expensive & takes time to order from Japan.
From Mr Badas-87 reply I tend to agreee that the additional devices are
: TPS -throttle position sensor - 3 wires
: Bowl Vent solenoid - 2 wires -which has evaporative emission functions
From the datas on the replacement carb, I believe it is manuafactured in 1997 for Japanese domestic markets - where our scrapyard importers got their 2nd hand parts.
As my vehicle is without ecu version, I intend to leave the TPS & bowl vent solenoid on "open circuit" & then try to fix onto the manifold - after removing existing 11 year carb & then try to start/run the engine.
If works then I will have one running & a back up carb - the existing 11 year old.
If I could lay my hands on an ECU ( if sufficient dats/information are available from this forums & members help) I would be pleased to try & to up-grade my vehicle & be more environmentally friendly - with the new carb.
Thanks to all of you again - until, I try out & report if any problem.