I was working on the injectors and broke a wire from an sensor on the left hand side of the vally between the first and second injector........ the probelm i am having is i do not know what kind of sensor it is to get a replacement.. can you please help nissan 300zx 1984 vg30 non turbo

Hi Stephen, Im AL the owner of Big As Auto Repair.

Stephen, here's how you diagnose if its the "Engine Controller" OR the "Wiring Itself". If you have or can get your hands on a test light, then here's what you do. FIRST: Unhook the number 5 Injector and attach the test light across the terminals of the connector. Then start the engine and see if the test light is pulsing on and off real fast. If you have no pulse at the connector that plugs onto the Injector, then move to the engine controller. NOTE: before checking the controller disconnect the negative battery cable so you don't damage the controller. NEXT: You'll need the connector still plugged in for the test, so remove the connector from the engine controller and back probe from the back of the connector the number Injector Circuit. NOTE: DO NOT probe on the side that plugs into the controller, do it from the back side. NEXT: Plug the connector back into the controller and start the vehicle. If you do not have a pulsing light then the engine controller for the number circuit is bad and will need a new controller. If you DO have a pulsing light then its in the wiring OR the connector at the Injector. If you have OR can get your hands on a DVOM which is a digital volt meter you can check which wire is at fault. Here's how. Disconnect both connectors at the Injector and the Controller and put the meter on OHM's then you can probe each wire from the Injector to the Controller to see if the wire is broken. If the meter has a beeper you will hear it beep, if it doesn't you will have a reading on the meter. When you find the wire that's broken run a wire from the Injector connector to the Controller Connector by wiring to the wire coming out of the back of each connector. If you should need further assistance please visit my auto-repair-website its free: http://www.bigasautorepair.com/

You can confirm each injector is actually working. Get a momentary switch, 2 feet of wire and some spade terminals (or whatever your connectors take). Disconnect the plug that connects to your injectors. Determine which injectors are controlled by which 2 wires. Connect 1 wire to the Positive 12V side of battery, then to one terminal on your switch. Connect a second wire from the other terminal of the switch to one of the two terminals of the injector you are testing, then connect a wire from the second terminal of the injector to any good ground on the car, or back to the Negative 12V on the battery. With the engine off, push the momentary switch on and off you should hear the injector clicking. If you hear the clicking that injector is working. Repeat the procedure for all other injectors. To avoid and shorting issues the wire going to the positive side of the battery should be connected last, and make sure no part of the wiring on the positive side touches any metal during this entire procedure.Disconnect the positive wire after each test to avoid any accidents.

Check continuity between the injectors and the ECM. if it's more than 5 ohms, repair the wires.

So, it's the injector circuit. There is a 10 amp injector fuse in the fuse block, on left side, 4th one down. Check this fuse. It supplies constant power to both injectors, on the red wire to injector 1, and a white wire splice from this to injector 2. A steady 12 volts anytime key is in on, run, or start. You can check this with a test light or voltmeter. Ground the test light and probe injector connector's red wire on injector 1, and the white wire on injector 2-both should be hot with key on.
This may be why the noid light didn't blink. The noid light must have this steady power signal, and when the computer internally grounds the injector ground circuit for a split second, you get injector pulse-or a blinking noid light.
You can check the ground circuit separately with a test light also for each injector. Place the ground clip of test light on the POSITIVE battery post, and probe the blue (ground) wire on injector 1, the engine must be cranking over, and the test light should be blinking. Do the same for the green wire on injector 2. If the test light is blinking on both ground wires, with engine cranking-the ground circuit is good. You are sending power down the ground wire to computer, and when the computer grounds the circuit, the tester will light up-it will blink because the computer only momentarily grounds the circuit to cause pulsing of the injectors.

I will give you what the codes mean and you can then work out what to replace.
code p0171 refers to system too lean--bank 1===causes intake / exhaust leak---AIR system---MAF/VAF sensor---fuel pressure/pump---injector/s---HO2s
code p0201 refers to injector 1--circuit malfunction===causes--- wiring--injector ---ECM
code p0202 refers to injector 2 --circuit malfunction===causes --wiring---injector--ECM
code p0203efers to injector 3 --circuit malfunction===causes---wiring--- injector --ECM
code p0204 refers to injector 4 --circuit malfunction===causes ---wiring ---injector ---ECM
code po321 refers to crank shaft position (CKP) sensor/engine speed (RPM) sensor---range / performance problem===causes---air gap---metal particle contamination---insecure sensor /rotor --wiring---CKP/RPM sensor.

Either the harness is bad,or the cam sensor is the problem.

YOU EITHER have a broke wire or a bad pcm

No, not the ICM. Maybe your pcm is, or was, at fault. Or the injector wiring. The injector circuit is pretty simple. The injectors fuse (under the hood) has power to it with key in on or start. so each injector always has power to it in run or start. the injector ground wire goes into the pcm where it is internally grounded for a split second-and that is how you get the injectors pulsing-when the injector circuit is internally grounded. Those internal grounds have been known to fail, just not often.
If it happens again, check the injector wiring, look for bad connections or corrosion at connectors. Check for power on injector power wire with key in ON. Also pull the connectors to the pcm (take negative battery cable off first) and look for bent pins in the connectors or loose or corroded connections.

The injector is an electrical solenoid. when it has power and ground, the solenoid is energized, a pin is raised, and the injector opens to spray fuel out. It's pretty simple, much simpler than a carburetor with over a hundred parts to it.

You have a wiring problem on the control side wire . One wire will have B+ voltage the other goes to the PCM- engine computer . The engine computer suppy's a ground when triggered by cam sensor . Your problem is you have a bare wire touching ground making the injector fire all the time the key is on ! Check the wiring harness from the injector to the PCM for rubbed through spots !
The PCM must be inside the passenger compartment under the right side dash or behind the right kick panel . Here is a web site for free wiring diagrams . http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine size . Under system click on engine ,then under subsystem click on fuel controls . Click on the search button , then the second blue link. Second diagram down is fuel injector electrical circuit. Dark green wire is the controlled ground . That is the wire to check .

from the sounds of it its going to be one of 3 things 1) the injector is bad or 2) there is no power getting to the injector 3) bad relay switch.

1) to find out if the injector is good. pull the injector out and with some wire ground one side and touch the other side to your battery, every time you tap the wire to the bat you should here the injector click..

2) if injector is good get a test light and test to see if power is coming out of the wires that go to injector( on some vehicles you have to have the motor turning over befor power is sent through wire, so have someone turn the key while you check the wires with test light)