Ls3 with ls1 harness and computer. Car starts right up, if i turn it off it will not start back up untill i unplug the injector plugs then fire the car with them off, it back fires then i plug the plugs back in and it fires right up. Codes

p0118
p0342
p0740
p0785
p1860
p1810

Also i extedned the cam sensor plug to the front because of the ls3 cam sensor and also crossed the two wires on the plug. Thanks!

 

P0118-Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
P0342-Camshaft Position Sensor Circuit Low Input
P0740-TCC Enable Solenoid Circuit Electrical
P0785-3-2 Shift Solenoid Circuit Electrical
P1810-TFP Valve Position Switch Circuit
P1860-TCC PWM Solenoid Circuit Electrical

 

I bet that ECT code is your big problem. See what the Pcm says the coolant temp is and then you may have to check those wires.

 

I am kinda of a noob but what about the reluctor wheel on the crank? Aren't the LS3 58 tooth vs a 24 tooth for the LS1? Forgive me if you have already accounted for that.

 

It's a cam sensor circuit problem. As the ecm doesn't know when to fire the injectors.