Here's a brief history - when I was running my OBII pcm I got codes 335 & 336 for the crankshaft position sensor. Found some wiring issues in the harness (insulation had baked off from several years of from header heat). Cut out the bad sections and soldered in new sections of wire. Affected wires were for the CPS, Knock Sensor, starter, front & rear pass. side O2's, and a ground wire on the block. Tested each wire with an ohm meter and verified all connections were good before wrapping the harness with heat tape and carefully routing everything. Car ran fine and the codes were gone.
A few days later my OBDI conversion pcm came in from Ion, so I swapped pcm's and started doing some Datamaster logging. Everything looked good and all sensors were reading appropriately (tune looked dead-on too...thanks Ion!). A few days later, I got code 43 for the Knock Sensor. Visually inspected the lower solder connection and the connection to the sensor itself yesterday and both looked good. Only possibility I can think of is either the upper solder connection inside the harness or the sensor itself. I'm waiting for more heat tape to come in, as I'll have to rip the harness apart again, so I'm just waiting at this point. Went ahead and swapped the OBDII pcm back in yesterday to see if it shows a code for the knock sensor and it does not.
On the way into work today, it died taking off from a light and would't start again. Engine cranks and I have 42psi fuel press. but it won't start....had it towed to the house, pulled the codes and it shows 335 and 336 again....WTF??
I'm going to swap the OBDI pcm back in to see if it starts, but I'm thoroughly confused here. Could this be a bad Opti? I'll rip the harness back out and test the wires again but I really don't think that's it....all connections were soldered, shrink wrapped, and tested before reassembly. I also put the factory wire loom inside of a Summit heat loom that's good to 1000 degrees and wrapped the holy sweet bejeezus out of all that with heat tape. Any ideas how to troubleshoot this crap??

 

Update: Just swapped the OBDI pcm back in and it still won't start. Guess I'll pull a plug to see if I'm getting spark or not and try to troubleshoot as a normal no start condition. Haven't had to do this on an LT1 yet...what are the most common culprits once fuel is verified to the rails?
I read Shoebox's write-up on testing the Opti but I don't have an Ohm meter that reads in the mega-ohm range. Mine only has X1K and X10....assuming this isn't good enough, but I'm a bit shaky on electical theory and multimeters in general. Any other way to test the opti??

 

Another update....found a blown 20 amp fuse in the panel under the hood. Replaced it with a 15 amp (couldn't find a 20 and don't want put a 30 in there) Diagram labels it as "Engine Sensor".....anyone know what all's on this circuit and why it would prevent the car from starting?

 

When you put the OBD-I PCM in, you either needed to have the OBD-I PCM modified to accept the signal from your 1997 100Kohm knock sensor, or you have to swap in the 4Kohm knock sensor used in the 93-95 OBD-I engines.

That would explain DTC 43.

On the fuse you replaced, what was the # (from the identification label on the box cover)?

 

Thanks Injuneer. Ion programmed the PCM for my conversion, so pretty sure that's not the issue. I actually proved it by going ahead and ripping the harness back out....apparently the 1000 degree wire loom and Summit heat tape wasn't enough. Found a small burn spot that didn't quite burn through but got the wires inside hot enough to stick together and slightly melt the insulation, causing a short which blew the fuse (it was #10 btw).

At this point, I'm not very confident in being able to protect the wires in the stock routing configuration and am measuring how much wire I'll need to route them over near the battery, down to the K-member, and then up to the various sensors. Looks like I'll need to add roughly 4 feet to each wire, but I'm worried the extra resistance might throw off the accuracy of the sensors, especially the knock sensor and O2's. Any idea how far I can safely extend these wires without screwing up the readings?

 

If we can use these which have connectors at each end,
https://www.casperselectronics.com/M...Category_Code=
you can certainly solder and shrink wrap the harness. It will have less resistance then adding 2 connectors. Just be sure to add length to the harness between the PCM and the connector, not between the O2 and its connector. Those O2s get their atmoshperic O2 from the wire passages in the back.