I'm an automotive service tech. I need this component built to boost a signal of a sensor. Now why do I not replace the sensor? Because, doing so would require 15 hours of labor. The signal from the sensor is 'weak'.
The inputs to the op-amp are backwards. Your gain setting resistors should go to pin 2 and your input from the VSS should go to 3.
One of the power supplies is backwards. Pin 4 should get a negative supply and pin 7 should be positive.
There are more modern op-amps to use than the 43 yo 741.
Most likely the VSS signal starts at 0 volts and goes positive. There are no negative excursions. You can find a single supply rail to rail op-amp and eliminate one of your 6v batteries. Change the other battery to 9v and you can use a common PP3 battery to power it if the PCM can take the higher voltage.
I don't know much about electronics. I got the schematic from a different fellow who made that same device his vehicle. If there is a better method, or technique it'd be appreciated.
Ok, if you want the negative output you will need to stick with dual batteries.
As I said before the pins are not correctly shown in the drawing.
Pin 2 is the (-) input, it gets the junction of R1 and R2.
Pin 3 is the (+) input, it gets the VSS signal.
Pin 4 is the (-) power connection. It gets (-) 6 volts, referenced to gnd.
Pin 6 is the output, it is ok.
Pin 7 is the (+) power connection. It is ok.
I decided to build the circuit myself. But, i am a little bit confused. I've 2 sensor wires. It appears, one sensor wire is cut and fed in to the amp. But the other wire looks like its spliced in to the other wires?