Alright fellas, I have done some research, but this is new to me and Im not really understanding what I am finding. Hopefully someone on here can break it down for me and offer some help.

My setup:
CA18
18g turbo, Vibrant MBC
450cc, Nismo FPR, 255
Nistune Type-1

First of all, and the most important issue, is my knock sensor. My ECU is constantly throwing the Knock sensor code. When I clear it, it either comes directly back up or within the next 15 seconds. My motor is not knocking. Obviously you cant tune with a bad knock sensor, as it is just pulling timing and dumping fuel, and I need a fix now. The wiring to the knock sensor is correct, and is providing the 7-8v. I read on the Nistune boards that the ECU needs to see about 3.6-3.8v to be happy and not throw the code, so you wire/solder in the 500k ohm resistor to make this happen. Though they dont explain how to do this. Do you keep the wiring as per usual, connected to the knock sensor, and just wire in the resistor inline? Any insight on this would be helpful.

Secondly, my N60 MAF does not seem to want to operate correctly. When wired in according to wiring diagrams on this site, I throw the MAF code and the engine behaves as if it is unplugged, revving only to 2k rpm. Even when using the stock MAF, which reads nowhere near enough power for what I am aiming for with my setup, I have to run an additional external chassis ground off of the MAF wiring ground to get it to operate correctly. Ive read of a lot of people having MAF wiring issues, and was curious as to if anyone had similar issues when attempting to wire in an N60/N62 MAF.

Other than that, the car is running and driving, just untunable until these two issues are resolved.

I appreciate the help in advance.

-Tyler

Knock sensor: You're not understanding the operation of the sensor correctly. The ECU sends voltage out to the sensor. Under normal circumstances, the knock sensor has a fixed amount of resistance to ground (the knock sensor only has one wire, the power going to the sensor, then it grounds through the body of the sensor). As knock is encountered, the resistance to ground changes. The ECU "sees" this as knock and pulls timing and adds fuel. If the sensor resistance is out of range, the ECU logs a code and runs reduced timing and increased fuel.

The 500K ohm resistor is so that you can remove the stock knock sensor and not throw a code. The resistor is wired so that one side connects to the knock sense wire, and the other side is connected to ground. This will make the ECU happy, but you won't have any knock protection either.

I don't know Nistune that well, but I would say that either you have a bad sensor, or the Nistune requires a different knock sensor than what comes equipped to the CA18.

First of all, thank you for the explanation of the knock sensor. I knew what it did, I just didnt know how it operated. But Im glad you said something, because the very limited amount of responses I got on this the 2 people that replied told me to keep the knock wire plugged in to the knock sensor, and to just run a resistor inline. What youre saying, at least what I am gathering from it, is to cut the knock wire, solder in the resistor, and run another wire to ground from the other end?
I did a lot of searching, and 500k ohm is the right size resistor for the CA, not 1m ohm like the SR. Nistune operates properly with the stock knock sensor, mine is just no good. I will find one as soon as possible, but for right now, the $1.50 resistor will have to do.

Glad I could help!

Quick question, when installing the resistors, Im assuming to run the single knock sensor wire directly to ground with the resistor inline?!

yes, like this;
ECU->knock sensor wire->500K Ohm resistor->Ground

remember the resistor isn't polarity sensitive, so it doesn't matter when end you connect to what.

Thank you. I just wired the knock sensor straight to the ECU for now, wanted to try that before I did the resistor gig. Havent started the car since though. Will update.

If you can only get a 470K or 510k would you use the 470 or the 510k resistor ?

510k, most resistors rated resistance is only accurate +/- 10%