Versa; Idle; RPM's revs up and down
I know this thread is old but wanted to share my experience in case this can help anyone else out. 2007 Nissan Versa. Change spark plugs, put in ignition coils, and put new gasket on intake manifold. While I was at it, I've decided to clean the throttle body. I open the flap can clean inside really nice. Later I found out that I was not supposed to open the flap. Oops. Got everything put back together and the engine would not start at all. Tore my hair out for two days trying to diagnose. On a whim, I decided to buy more spark plugs and install them. Car fired right up.
These were defective
Autolite XP5684-4PK Iridium XP
These worked perfectly. Denso Spark Plug Iridium TT
Then a new problem. At idle engine would rev up and down, up and down. 2,000 to 3,000 rpms. Check the fault codes with an ODBII scanner and an app called Torque I got on my smartphone. Fault code read P0102 which is Mass air flow sensor circuit low input. So I took out the sensor and sprayed it with Mass airflow cleaner. Let it dry and put it back in. I reset the fault code and started the car back up. P01102 code went away and got a new code. P0507 which is Idle air control - RPM higher than expected. Still at idle car revs up and down continuously. I read that a clogged PCV valve could be the culprit. Bought a new one and installed. Still revs up and down. Could be anything from a vacuum leak to throttle body to Mass air flow, etc. I sprayed starter fluid around manifold and hoses to try and detect a leak. Nothing came up. I also did the relearn procedure for the Accelerator pedal, throttle valve and Idle air volume learning about 20 times. Still at idle rpms revs up and down. Browsing the internet I read that somebody said it could be a faulty ignition coil. They were all new, but what the hell. I installed the old ones, except for the one I knew was damaged. I also over tightened the intake manifold bolts and throttle body bolds beyond specs. I thought maybe there could be a slight leak. Viola, car started and began to idle normally to 650 to 700 rpms.
Intake Manifold torque specs are 20 ft lbs. I tighten to 25ft lbs *Foot pounds.
Throttle body torque specs are 89 in lbs. I tighten them to 100-inch lbs. *Inch pounds.
So changing the ignition coils or over tightening the bolts fix the idle fluctuation? I'm not sure but, it's fixed.