I have a 99 Nissan Quest, Just recently changed the knock sensor and o2 sensor.. after i finished the van ran beautiful except for the o2 heater circuit which i tracked down to a couple of cut wires. I repaired these and restarted the van and that day it ran fine. It sat over night and i started again to get it ready for smog and it had a high idle like 1800 rpm. So i actually removed the upper intake and replaced all the injector seals thinking that it may be that due to one being broken. now i have to give it a bit of gas to start it and it still has the high rpm (1800) i have traced the high rpm back to the IAC but the the starting problem i have not located. Even though i found the high idle problem i am still unable to find out why,
What i have done:
Changed knock sensor
all new intake gaskets
followed the Nissan service manual for installing the intake
changed the o2 sensor
repaired 3 broken wires for the o2 sensor
cleaned throttle body
It kinda sounds like a vacuum leak but i have had no luck locating one, I don't know if the engine just sounds like that normally or if there may be a leak. Never had this problem before.
I am stuck with a van that runs smooth and has power just a high idle and hard starts has anyone come across this problem before. Any information would be greatly appreciated and any more information will be given if needed
Thanks