After my last post about the ECU throwing the knock sensor code (5), I went back to my engine builder and we spent some time swapping the ECU with a known working one. Still got the CEL light, still throwing the same code 5. Even went as far as directly connecting a knock sensor to the correct pin on the ECU, so bypassing any dodgy wiring there might have been in the harness. Still code 5!

So what happens now is that when I start the car up, the CEL light comes on. But after its nice and toasty under the hood, after 10 mins or so of driving, the light goes off. Performance when the light is on is somewhat sluggish, although I am getting boost. When the light is off the car becomes its normal awesome self. I guess it's out of its 'limp mode' at that point.

Car is a stock 93, non-Cali.

Any ideas worshipfully received.