Nissan Repair: 1996 Nissan 300Zx TT - Engine hunting, nissan 300zx tt, nissan 300zx

Question
Dear Sir,

I have had this fantastic car for a few years and for about a 6months now it has been hunting on idle and acts like it wants to cut out...which over a period of time if left idling cuts out....as the fault has become worse.

I have read a few of your other posts which suggest the idle air valve may be faulty or the PCV sensor faulty. (PCV - have no idea what that is unfortunately)

To help you, i have carried out a flash code diagnostics on the car which shows no recorded faults.

Can you suggest help by any chance?

Much Appreciated,
Nav.

Answer
Nav,

Sounds like an idle air control (IAC)valve that needs to be replaced.  There is, of course, the manifold absolute pressure sensor (MAP) sensor that gives a signal to the IAC that could be worn out and that would give bad data to the computer.  But, most of the time the hunting idle would be the IAC.  Also, the Positive Crankcase Ventellation Valve (PCV) valve is what allows the engine to suck out water vapor and acid vapors off the crankcase.  Basically, it is a restriction with a check valve to keep a backfire from entering the crankcase.  You see, a backfire could cause the oil to catch and blow the pan off the engine, if the car actually backfired.  So a PCV valve is a good thing to have and over the years it gets gummed up and then needs to be replaced.