I recently discovered that the inter-cooler pump on my 98 Super V8 was unplugged from its power supply socket and its socket was instead plugged with a blue coloured plastic blank! I can't think of any other explanation except that my pump had NEVER been plugged in since car assembly. Surprisingly, my cars ECU has never recorded a P1113 code (high air-intake temp from IAT2 sensor).

Consequent pump connection yielded a subjective improvement in throttle response/horsepower and an objective 8% improvement in fuel economy, which is not surprising given its previous inefficiency of passing intake air though a heat soaked inter-cooler (i.e. inter-heater) even when not on boost.

Does anyone have an alternative explanation for why my loom socket would be blanked off?

I assume that my car is the exception, but it might be worth confirming that your own cars inter-cooler pump is connected. Its easy to check - both inter coolers should be considerably cooler to touch than the supercharger & engine after driving. You should also hear the pump running (under hood with ignition on & engine off). The pump wiring connection is a small 2 wire D plug & socket which is attached to the underside of the front right hand side (facing forward) chassis rail.

 

that's super weird!