Hi,i have a 2001 wrx that is a little poorly.To give a little background the car has a stage one upgrade to 285 bhp by means of the following;
straight through 3inch exhaust,
255 fuel pump,
boost controller,(set at one bar)
APS air filter,
APS intercooler piping,
UNI CHIP piggy back ecu,
The car has been running very well for about three years,(since upgrade) but now keeps throwing up cel 304 (missfire on cyl 4 ).It was starting to be hesitent and a little rough.I have not noticed any major power loss although when running rough its hard to tell.It has since been to a garage to diagnose the problem and after a morning and a 170 pounds later they have told me that after a compression test things are not good.! The test results were cyl 1 & 3 @ 155 & 158 and 2 & 4 were 100 & 85 The garage said this is not good and they should all be roughly the same .They now say they will check timing but i dont know if thats right or not. HELP.
Any of you techs out there with any ideas,either on possible causes and or what to do next please feel free to reply.Thanks.