Retrieved the the following error codes from my 93 z28.
#28 - transmission Range pressure switch assembly.
#33 - Map sensor
#45 - Bank 1 (left) heated oxygen sensor (HO2S) circuit (rich exhaust indicated)
#65 - Bank 2 (right) heated oxygen sensor (HO2S) circuit (rich exhaust indicated).
My question is does the map sensor create the problems with both HO2S sensors? Or are they all separate issues that need to be corrected.

 

Use Shoebox’s code list, specifically for the LT1 engine. Note the 1993 codes differ slightly from 1994/1995. They are shown in the right hand column, where they differ. DTC 28 is for Quad Driver #3 which controls both the fan control relays and A/C (clutch) relay. DTC 45 and 65 are for the O2 sensors, but 93 sensors are not heated.

http://shbox.com/1/Dtcs.htm

93’s run speed-density (no MAF sensor), In that system, the mass air flow is calculated from the RPM, inlet air absolute temperature, and manifold absolute pressure. The ECM then uses calculated mass air flow to determine how much fuel is required, and sets the fuel injector pulse width to deliver that amount of fuel. So a faulty MAP sensor could cause a “rich” condition.

DTC 33 indicates MAP circuit signal voltage high - low vacuum. The low vacuum indicates a high engine load, so it will cause the ECM to add excessive fuel. That will cause DTC 45 and 65 to set.

Here's a link to a free download of the 1993 factory service manual (courtesy of GaryDoug). It's for a Firebird, but everything related to the engine is identical to the Camaro,

https://www.mediafire.com/?40mfgeoe4ctti