Hi i had an hks fcd fitted to my 92 wrx,it works some times and not others,i cannot understand why it does this the wiring looks right the only thing i can think is a while ago i swapped my map sensor over with my mate because i thought it was faulty,his car is a uk car are the map sensors different and what should a 92 wrx see fuel cut at,mines is doing it at just under a bar which i think is to low can anyone help .
Johnny

 

The Map Sensor from a UK car is not compatible with a WRX (what I was told by Barratts Motorsport). The Map sensor is probably giving higher voltage readings hence causing your WRX ECU to apply fuel cut early.

Get yourself a 2nd hand MAP sensor from Grade A Breakers, and see if it sorts itself out.

Hopefully you still have your old MAP sensor as the part number on top is very important.