Nissan 300ZX efi fault

[kleenair at ix.netcom.com]

Ross Forgione wrote:
> 
> Hi all,
> 
> I work with a high flying sales person type dude, who is in his 30's and
> is suffering from the old mid life crisis problem. Soultion to problem,
> purchase a sporty type car.
> 
> The car is a Nissan 300ZX model listed below. Anyway long story short,
> he bought second hand from a local car dealer after lots of warning
> from myself. Has spent lots of $$'s fixing the usual faults with cars,
> (hoses, leaking fuel seals etc ...) but there is one fault that even
> the local Nissan (real 100% factory appointed) cannot resolve. I have
> listed it below in the hope that somebody out there may be able to
> light a small candle showing the direction we should take in resolving
> the fault.
> 
> Have pity on the guy, It real hard to look cool when the cars on tow
> as the pretty ladies go by.
> 
> Any help at all will be greatly appreciated.
> 
> The problem as follows:
> 
> Make:   Nissan 300ZX Turbo 1986 - Fuel Injected
> 
> About 80% of the time the engine has a problem of surging then dying when
> at 1700-1900 RPM it refuses to cruise at this RPM level. The engine still
> accelerates and decelerates smoothly but will not run evenly whilst trying
> to keep at a constant speed.
> 
> The problem can be fixed 100% successfully after driving a few KMs by
> putting the car into neutral and switching the ignition off for 2 or more
> seconds the restarting the engine.
> 
> If I park the car and leave it for an hour or so the majority of the
> time I will need to start the engine drive for a few KMs the switch the
> engine off and on to get it to run smoothly again.
> 
> If I start the engine then stop it immediately then start it again when
> I first get into the car it still will not cruise at 17-1900 RPM most of
> the time.
> 
> Hot or Cold weather makes no discernable differance to the behavior of
> the car.
> 
> It is a bit of nuisance having to switch the engine off every time I
> drive it.
> 
> I have taken the car to a Nissan Service Centre but they are not sure what
> the problem is. They think it may be one of the computers being faulty
> but they are not sure which. I dont think much of having to pay $1500 to
> have both computers replaced when they are not certain which one it is
> or even if it is actually a computer fault.
> 
> If you can find anyone that has had similar gremlims let me know.
> 
> Thanks,
> 
> Ross.
> 


I don't know any specifics about the Nissan system, but try checking the 
following:

-EGR valve operation:  Is it getting stuck.  Try disconnecting it and see 
what happens.

-O2 sensor(s):  Are they still working?  Put a volt meter on it to see.  
It's possible the computer is attempting to go to closed loop.  Does it 
have heated O2 sensors?  Is the heater working.


Best Regards, Mazda