Trouble w/ code 34
 

I've had my 1990 Z32 NA for a couple months now. Bought it as a restoration project of sorts and a toy for the most part.
Anyways the car has run like crap ever since I got it. Runs fine in 1st gear and idles fine but trying to shift into 2 results in power loss and a case of the shakes. Ran codes today and the only code is 34. Simple enough just relocate the knock sensor and problem solved. Only problem is the previous owner did a ton of work on the car and threw in a new VG30DE and from what I've seen he sucked at running wiring. So the problem is I cannot find the harness connecting the ECU to the KS sub harness. What are my options if it happens to be non existent? Run a direct line from the ecu to sub harness or what?
I've seen pics and videos of where the harness/plug should be at the back of the plenum but I can't find it. All I have found is the plug to the sub harness (or at least that's what I think it is).
I know it's a weird problem but you guys seem to know these cars pretty well and seeing as I'm completely new to them I'm turning to this forum for any further help lol.

Thanks guys

Anyone? Lol
I'll be working on the car after work today.
Until I get something other than a bottle jack I'm just searching the engine bay for anything unplugged. I have found some things but I'm almost 95% sure they were from the EGR bypass that the previous owner did. Does anyone have a pic of where the sub harness for the KS comes out from below the plenum?

My harness isn't in separate pieces. It's all one unit. I did find however the harness you might be talking about on ebay. Is all your transmission connection there? Also the oil sending unit connector there? If so all of this is part of this sub harness being sold on ebay.

To be honest I haven't checked what's around it. I saw on Z1 where they sell a bundle with the sensor and a sub harness. That sub harness plugs into something and that something is what I'm trying to find lol.
I honestly don't even know if I'm looking in the right place. Maybe I should be looking lower behind the engine? Everything I'm seeing is on top behind the plenum if that tells you anything. I have been guessing that is where the KS harness exits but I don't know that for sure. I know where the knock sensor is exactly but I have no idea how the harnesses and such are suppose to run from the sensor to the ECU. It's a mess I know.

Okay so if my harness is in one piece like yours is there a way I can chop off just the two wires I need and splice them with connectors to simply relocate the sensor?
Also does anyone know what color wires are running to the det sensor?

My harness comes out of the passenger side firewall, branches up to alternator and back to transmission. Then climbs up and runs to the drivers side. Branches off back toward the passenger side for fuel injectors, coil packs, O2 sensors, VTC Sensors, etc. then back at the last branch it extends to front of motor getting TPS/Potentiometer, CAS, Coolant temp sensors, PTU and MAS.

Sure you can. When I did my TT swap I had to extend/reroute my Oil Sending Unit connector from the passenger side to the drivers side as the Sending Unit is on opposite sides of motor. At least this is true for the JDM Motor.

Simply cut the wires about 5 inches from the connector. Strip the wires on both ends of the cut. Then splice your wiring to the harness side and run as much wire as needed. Then splice the connector back into the new wiring. Be sure to keep colors correct.

Okay well I didn't get to look at it yesterday but I'm off work today so I'll spend my day poking around in the engine bay. I found a wiring diagram online yesterday so hopefully that combined with your description I'll locate this thing once and for all.
I really appreciate the help!

Another question: running codes again today after throwing on a used knock sensor that I got for free and I'm getting code 51. I might have gotten this before but didn't pay attention. If the car sat for a few years in a garage before I bought it is it possible that fuel injector cleaning could clear this code or is it a definite failing injector?

Just saw this is injector circuit and not injector leak...
Any tips? Just check all wires and connectors?

To check if the injectors are firing you can do a couple easy things.

1. With the engine running put a long screw driver on top of a injector and stick your ear to the end. You will hear a very distinguished clicking sound. If not then the injector is not firing. You can compare the clicks to other injectors to determine if they are firing or not.

2. Pull the injector connector off while engine is running. If the engine RPMs drop then it is firing. If the RPMs do not drop then it is not firing. I usually just pull the coil pack connector to find the dead cylinder. They are easier to remove and put back on.

Once you have found the misfiring injector you can use a test light to check and see if you are getting signal. While engine is running, put the wired side of the test light on the negative battery terminal and probe each wire on the injector in question. Then reverse it by putting the wired side on the positive battery terminal and probing each wire. By doing this you should have found a combination where the test light was flashing. This will show that the circuit is good to the end of the harness and the injector itself is the issue. Further diagnose the injector by performing an ohms test on the injector itself. If the test light did not flash then you have an open in the wire somewhere.

Thanks! I ended up just pulling all the connectors until I found that number 5 cylinder wasn't firing. Upon closer inspection I found that on the connector one of the wires had completely corroded in half while the other was exposed and oxidized. I have an extra engine harness from a junk yard car so I just spliced in a new connector and now she's purring like a kitty!

Thanks guys for the help!

Problems are all resolved!

Good deal. Now enjoy her until she breaks your heart again.