So I bought a 1992 300zx TT Import with a slight misfire/hesitation and thought it would've been a simple fix. It seems not.

 

I've replaced the spark plugs, the fuel filter, swapped out the miniscule battery for a beefier one and ran injector cleaner through the engine.

 

The misfire occurs when it's cold and continues to do so until the needle is about a quarter in its travel. Once I boot it when its warmed up there is no misfire and she runs smoothly.

 

Except for yesterday. It was late at night, and chucking it down with rain. Usually when all the components are warm the misfire disappears, but this time it was odd. When i put my foot down slightly the engine revs would drop as if something was choking it - it also did this with the clutch disengaged. Today, after trying to diagnose the problem, the problem wasn't there to diagnose.

 

Could it be:

Injectors?

Coil Packs?

A/F Ratio?

Throttle Bodies?

Vacuum leaks?

Timing?

 

If it is any of the above, how do I go about checking them?

 

Cheers

or could be the maf ?

I have a very similar problem, according to datascan all is ok but I still have the problem , swapped tps, ptu, mf to no resolve. New plugs etc, gonna do a boost leak test next step z world. I watch in antisipation

Sounds like a vac/boost leak

Also check for corroded plugs and terminals on the injectors especially, temp sender on the water pipe at the front of the engine,