i just bought a Sentra B12 1.5 SGX and im confused kung bakit palagi nalang bumababa to 500-400rpm ang idling ng kotse. No matter how the mechanic adjust the idling to 800-1000rpm, bumabalik pa din sya to 500rpm after i let the engine cool down. This is my 3rd time already to have my idling adjusted and still it goes down even upon AC on, exactly the same 500rpm. After adjustment, akala namin ok na, pero pag-uwi ko ng bahay then start ang kotse after mga 2hrs, balik ulit to 500rpm. tumataas lang sya pag nag-engage na ang radiator fan, pero konti lang itinaas. Ano po kaya ang problem?