Where is this device located and how can you tell if it is bad? Can your car run without it? Pictures are good....

My Factory service manual for '95 shows the L67 knock sensor on the back of the engine to the left and above the oil pressure sender. The single wire for the knock sensor comes out of the same sheath that runs to the vehicle speed sensor on the transaxle. The knock sensor is threaded into the engine block, with its face immersed in coolant. If you disconnect the wiring to the sensor, the PCM will set a check engine light, (code P0325) and will retard the ignition timing of the engine by 10 degrees to help prevent damage from detonation that it can no longer detect.

The car will run if the sensor is broken or disconnected, but should set a check engine light and will be very sluggish, especially noticeable when you try to accelerate rapidly.

Check the wiring to the sensor first to make sure it is OK. Squeeze the oval-shaped connector into a circle to remove it from the sensor.

Resistance measured from the output pin of the sensor to ground should be around 3.9Kohm. You need sealant on part of the threads to keep the coolant from leaking and the sensor from rattling, but the threads must be able to make an electrical ground with the block, and the end or face of the sensor must be clean to "hear" the knocks clearly.

Without a scan tool, you can unplug the wire to the sensor, and connect a voltmeter set to measure a couple of volts AC on the output pin and ground. Tap on the engine block and watch the meter, it voltage is produced, the sensor is probably OK.

If you have a scan tool, set it to show KS count and strike the engine lifting ring - this should cause the sensor to register a knock shown as an increase of one count on the tool.

The face of the sensor immersed in coolant can get covered with sludge and become less sensitive, and they can just fail. They should be torqued to no more than 14 ft-lb if you replace it. Overtorquing makes them oversensitive and can destroy them.

there are 2 one in the front of the engine and one in the back....some one will chime in with a pic im sure

I'm starting to think knock sensor location depends on who put it together. Some say on the back near the oil filter, some say on the front above the starter. My 92 L67 has one on the rear, the 93 SE parts L27 has one above the starter. It goes back and forth from year to year.

Yeah, it can be confusing. My '95 FSM shows:

Series I L67 with one sensor in the back near the oil sender; threads in parallel to ground.
Series I L27 with one sensor in the front towards the middle of the water jacket; threads in parallel to ground.
Series II L36 with two sensors front and back middle of water jacket; thread in perpendicular to ground.

And if I remember correctly from my '97 SSEi,

Series II L67 same as L36

I'm hoping someone will correct me if I am wrong.

Jay...

You believe you have an exhaust leak in the front manifold, possibly catalytic converter etc.

Please address these first. A plugged cat will rob you of power. Once you get the cat straightened out and have fixed any other leaks, then testing the sensor(*) would be a good idea.

Fix all known problems first. And confirm them before spending any money. Do NOT shotgun parts. You'll pay through the nose.

And take that pulley OFF the car until it'* running correctly. It has a GOOD chance of making this worse considering the problems you currently have.