300zx z32 problems (maybe coil packs)

[Guest xtremebhill]

I had a newer motor swaped in my 90 na z32 its a jdm motor and it doesnt make hardly any power untill 4k rpms, and idles ruff.... the fuel pressure is good. I was told it might be a coil pack and that these cars blow coil packs alot, how can i check to see which coil pack it would be? Sorry if there arleady a post that says how to check i searched for coil packs and couldnt find much..

[Mayolives]

http://www.twinturbo.net

[Booztd 3]

What does the motor do when you free rev it to 4k?

 

These motors run pretty smooth even on 5 cylinders, so you may want to monitor what the motor is physically doing at idle. I'd suggest just putting the coil pack harness wires 1 coil pack at a time.

[Guest xtremebhill]

I tryed unpluging the coil pack wires one at a time but i didnt notice any differance... any way to check the coil pack out?

[Booztd 3]

If you free rev the motor in neutral, does it bumble the same way as it does under load?

[Guest emuthus]

this also sound like an injector is starting to go. i had the same problem on my 91 TT. i would ohm test the injectors

[waynekarnes]

from what i have read and talking with those in the know, the coil paks really do not go bad all that often. usually is corroded connection.

 

1st lets see if you have a dead cylinder.

 

1st figure out how to remove the electrical connector on top the coil pak. some have a catch that needs to be pressed to release em. others it appears can just be wiggled and pulled off.

 

once you get this figured out. leave connectors attached as they should be.

 

start the engine. parking brake on. wheels chocked.

 

with engine running, pull connector off easiest coil pak you can reach. if engine speed falters when connector is removed and smooths when reattached, that cylinder is fine.

 

work way through all 6 cylinders.

 

should you find one that makes no difference. engine runs the same, no stumble, no change in idle, you have found the bad cylinder.

 

if you go through all of em and no difference you will need to do more extensive testing to find the problem ( as suggested earlier, may be a bad injector. more info later ).

 

now supposing you have found dead cylinder, good deal at least you know something. one is dead.

 

suspect wiring or the injector before you suspect the coil pak.

 

injectors are a pita to get to.

 

easy test, 98% accurate.

 

use screw driver with long shank. 12 inches or longer.

 

with engine RUNNING, lean over engine. be careful around fan, belts, ect.

 

on one of the cylinders that tests good ( missed when you unplugged connector )

 

put screwdriver blade on top the flat metal bracket holding the injector in the fuel rail. hold blade firmly against that metal bracket.

 

put the handle of screwdriver to your ear.

 

with a good injector you will hear TWAK, TWAK, TWAK.

 

now that you have listened to a good one, you know what they should sound like.

 

move screwdriver to the dead cylinder. give a listen to that injector.

 

if you don't hear the TWAK, TWAK, TWAK then, that injector is not working. can be either wiring or bad injector.

 

cool trick : engine NOT running. remove connector from injector. grab a 9 volt battery. connect wires from 9 volt battery touch to connectors on the injector. should not matter which is neg and which is pos. when initially touch wires to connections on injector, if injector is not frozen or coil inside injector is not burned up, a GOOD injector will go TWAK once. disconnect one wire at injector, touch to injector again TWAK ! if you hear the TWAK from the injector that didn't go TWAK with engine running as you listened with screwdriver, the connection or connector is bad.

 

you can also check with ohm meter between connectors on injector. should read between 10 and 14 ohms. is cooler to hear the TWAK using the 9 volt battery. don't use the car's 12 volt, you may burn the coil on a good injector, use the 9 volt battery.

 

if you do hear the same TWAK, TWAK, TWAK on the dead cylinder as the good cylinder, this usually means injector is good and means no spark.

 

now we swap coil paks.

 

disconnect the connector on top the pak.

 

remove the bolts holding the clamp ( 2 bolts ).

 

vacuum and brush to clean any crud away from the pak and the hole it goes into.

 

pull the coil pak up at the angle it sits. is attached to spark plug at bottom of the shaft. plus has a rubber like tube that slides into the shaft. may take a steady hard pull to get the coil pak out of its hole.

 

remove coil pak from good cylinder.

 

remove coil pak from bad cylinder.

 

swap em. put the known good coil pak in bad cylinder. put suspected coil pak in good cylinder.

 

make sure both coil paks are bottomed into the shaft, is connected to the spark plug.

 

reconnect the wiring. no reason to reattach the hold down brackets ( yet ).

 

start the engine.

 

remove the connector from the coil pak in the good cylinder if engine speed changes, coil pak is good.

 

if no difference, suspect coil pak is dead.

 

put connector back on coil pak.

 

go to cylinder that is bad. remove the connector to the coil pak. if engine speed changes, then means injector is okay and connections are good.

 

if makes no difference, cylinder is dead. means bad injector or wiring to either the coil pak or injector.

 

already told you how to electrically test injector and determine with screwdriver if hear TWAK.

 

so, if you isolated the injector and we know the coil pak is good because we moved it from a good cylinder you will need to use volt ohm meter to test the wiring.

 

if you want to test the coil pak another way :

 

remove coil pak. put a spark plug in the business end of pak.

 

connect the wiring to the coil pak.

 

make sure there are NO FUEL LEAKS !!!!

 

don't SHOCK yourself doing this !!!

 

have someone start the car for you as you hold the spark plug to ground ( engine block )

 

a good coil pak and good wiring will make a big spark at the spark plug.

 

if no spark, make sure have good ground, try again. no spark coil pak is dead.

 

replace coil pak.

 

now think about injectors.

 

some injectors will die in the closed position, some in the open position.

 

closed is better than open.

 

open means flooding engine with gasoline. you will smell it in the oil.

 

check the electrical connections at front of the engine above water pump. corrosion there or loose connection can screw up readings to the computer.

 

you may also want to check crank angle sensor.

 

i am no expert.

 

just bought my son a 1990 zx for high school grad present. same issue as your car. found bad injector or bad wiring. haven't been able to get into the injector with 9 v batt yet. has been raining and busy. plus is the number 5. buried under fuel lines and balance tube.

 

it is surprising how well these cars run on 5 cylinders. on the turbo engine is really hard to tell from behind the wheel that engine is missing.

 

good luck,

 

 

wayne

[Guest lonewolf317]

I am also having the same problem. mine is on the number one cyl. my thing is that sometimes it works then sometimes it does not. I have come to the conclusion it is that the wires are almost completely corroded threw. there was corrosions all the way from the Ignition Mod to the number one coil. and I cant find anywhere to get that wiring harness.

[Clifton]

I am also having the same problem. mine is on the number one cyl. my thing is that sometimes it works then sometimes it does not. I have come to the conclusion it is that the wires are almost completely corroded threw. there was corrosions all the way from the Ignition Mod to the number one coil. and I cant find anywhere to get that wiring harness.

 

 

The injectors are also a problem on Z32's. Usually starts with a rough idle that clears up with in a few seconds or minutes, then one day it won't clear up.

[HowlerMonkey]

Then you've got that pesky egr valve.