Check Fault Codes, Cas, Ptu, Injector Connectors, Coil Pack connectors, Boost (vac)Leaks. TPS, IACV

What does Check Fault Codes, Cas, Ptu, Injector Connectors, Coil Pack connectors, Boost (vac)Leaks. TPS, IACV actually mean?

Well first, you have probably been directed here because you posted a generic question, with not enough information to diagnose.

Check Fault Codes

So lets begin by breaking it down, the 300zx z32 is a different beast to most cars, advanced for its time, with almost electric everything, first step is to check for fault codes, yes actually check, they dont all throw a light on the dash, what you are looking for is code 55. This doesn’t mean that everything is always good, but it means the ecu sees nothing it has been told to look for out of place.

Cas, Ptu, Injector & Coil Pack connectors

The Z32 can be prone to corrosion in the connectors, so start there, pull them off and check for green corrosion and stiff wiring, If thats the case, replace them, your z will love you for it.

The PTU (s1 square type) are also known to fail, sometimes (not always) will throw code 21, its more of a WHEN not an if it will fail, so its best to swap out with a S2 PTU before it lets you down.

The CAS or Crank Angle Sensor, is also an item that can cause no start issues, either its connector, or the sensor itself.

Boost (vac)Leaks

Yes, you with the NA, this still applies, Do a proper test by removing the nose panel, afm, and putting tester in, even the slightest leak will cause idle and hunting issues.


This is the Throttle Position Sensor, it has 2 functions, 1 to tell the ecu what percentage of throttle you are at. 2 to tell the ecu that you are off the throttle via the Hard Idle switch. Set it to 0.42-0.46v with the throttle closed.


The Idle air control valve, made up of a few different components is another main cause of hesitation, hunting and idle issues. You need to ensure its adjusted via the Base Idle Adjust procedure.