irregular missing

[illdrifter]

Ok so first off hello to everyone . So this is my problem . i own a 90 z32 auto w\ 50k on it . I dont know any history on the car . It started developing a miss so i checked yhe coilpacks and replaced ones that where missing as well as changed the spark plugs . That helped just a little then the skiping started n got worse so i changed the igniter chip and that cleared up all of the missing . But here i am a month later with the same problem . ughhhh . any help will be greatly appreceated . thanks again .

[robomatic12]

What spark plugs did you use? Our cars are very picky and you should only use the oem plug.

Is it missing on one cylinder only or a few? Does it happen all the time or only at certain times?

[illdrifter]

ngk spark plugs . It jumps around as far as which coil isnt fireing . It doesnt do it all the time . it is random at best .

[es.biggs]

Sounds like the PTU.

[illdrifter]

ive already changed the ptu out with one that i new worked . ie a running car . it worked for a while but it has started again .

[robomatic12]

If its the older style PTU they can die, or start to die like this. Get a version 2 PTU and subharness.

[es.biggs]

You might even be able to get the recall done by Nissan, for free

[illdrifter]

So i replaced the ptu with a brand new nissan one . Now the car is running better but not getting any action on the last cylinder on the passenger side . So i changed the coil with a brand new nissan one and there is no change still nothing on that cylinder .

[bartZ32tt]

How have you confirmed which cylinder it is? Do a power balance test - with car running, pull the connector on each coilpack one at a time. Listen for a change in idle. If no change, you found the problem cylinder(s). Then try swapping plugs/coilpacks from bad cylinder to any good cylinder. If no change, check injector resistance using an ohm meter. You're looking for 12.1 ohms iirc. Report back with what you find, but it's most likely your injector from what you described.

[illdrifter]

I checked the coils by pulling the plugs off on at a time . Then I swaped out the one that wasn't working with a brand new Nissan coil . Which I also tested on another fireing cylinder . It worked fine in other cylinders . I haven't had a chance to test the injector . All I need to do to test the injector is unplug it and touch the 2 prongs with a ohm meter right ? ? ?

[robomatic12]

Yeap, should be right around 11-13ohms.

[illdrifter]

Ok its a year later I've done a lot to the car since . Done a z1 conversion to the *new* style injectors and clips with venom injectors . Ground down the upper intake for easy access to injectors . Egr blocked and removed because of heavy buildup in the upper intake . I have come to the conclusion that this car has a wiring demon that plays nice sometimes . After doing all that the car ran amazing !!!! Probably even better than the day I bought it . Then the demon came out . Fried middle injector on pass side . Put a dohc ka injector in just for laughs and the car has ran fine ever since . Id like to thank everyone for the help on here it was greatly needed and appreciated .