I have a 90 camry with check engine light on. The knock sensor code comes up when checked. I removed the intake to get to the knock sensor but no sensors are found or a place for sensors to be installed. The engine is a 2VZ-FE. Do all V6 motor come with knock sensors or could someone have changed blocks. The plug to the sensor is not there. Cannot find any other place for sensor or where a sensor could go.

As far as I know, these are the only Toyota Diagnostic Trouble Codes for 1990 vehicles:

11 ECU Power Supply.
12 Engine RPM Signal.
13 Engine RPM Signal.
14 Ignition Signal.
16 ECT Control Signal
21 Oxygen Sensor (OS) Signal.
22 Water Temperature Sensor (THW) Signal.
24 Intake Air Temperature Sensor (THA) Signal.
25 Air/Fuel ratio lean.
26 Air/Fuel ratio rich.
27 Sub-oxygen sensor signal.
31 Air Flow Meter Signal.
32 Air Flow Meter Signal.
41 Throttle Position Sensor (TPS).
42 Vehicle Speed Sensor (VSS) Signal.
43 Starter Circuit Signal.
51 Switch Condition Signal.
52 Knock Sensor Signal
53 Knock Control Signal
71 EGR system malfunction.

Edited to correct information

I know the 4cyl doesn't but the 6 cyl 2vz-fe motor lists a knock sensor.

You're right. Even though the timing is set manually, there is a knock sensor mounted on the midline of the block (midway between the cylinder banks) under the water by-pass pipe. The list of diagnostic codes I found was incomplete and the timing is set manually. I assumed that meant there was no knock sensor.

Sorry for the misinformation