Check engine light comes on with codes p0112 and p0117, so I checked the sensors with a multimeter and they seem all good so i believe my problem is with the wiring in the harness. So my question is would it be ok to run the wiring for the sensor plugs through the firewall and splice straight into the ecu and grounds? Or would I just be better off getting a new engine harness because my current one is already pretty hacked up from a failed lsvtec attempt from the previous owner.
Edit: Forgot to mention its a stock b16a2 with gsr tranny

 

Dont see why you cant. People run vtec wire among others straight from sensor to ecu all the time. Assuming you know exactly what wires to what sensors. Since its already hacked up, dont see reason not to. For a cleaner look, you can alway source a spare harness in the event you f÷ed it up badly.

 

Those two sensors share the same ground... whatcha wanna bet your problem is there ??? The wires in question would be green with a black trace... and they terminate under the intake manifold at one of the two junction blocks.

 

Ok i got the codes figured out my coolant sensor temp plug and vtec pressure switch plugs got mixed up and the p0112 was caused by a broken wire, but now with a functioning iat i get misfire codes in cylinder 1 and 3. Replaced spark plugs and distributor wires and i doubt its the distributor itself because its brand new. Have yet to clean injectors,change fuel filter or do any kind of compression test but I only get misfire codes with that sensor plugged in. Only other check engine lights I have are for both o2 sensors because I'm not running any yet. Do you guys think not having a primary o2 sensor is causing anything or is my problem somewhere else? All on stock p2t ecu

 

No primary O2? You need all sensors working-- no CEL-- before you should expect the engine to run right.

When the ECU is satisfied with the sensors it will switch to "closed loop" which means the mixture gets leaner for better mpg. That leanness can reveal a problem like low compression (maybe valves too tight) or weak sparks.