Reduced power 99MY Impreza - intermittent
 

Hello My 99MY Impreza has reduction in power right across the rev range. While driving if there is a reduction in power I switch the ignition of then back on again, which used to sort it out for the remainder of that journey. But recently the reduction in power is permanent right from the of. Hope someone can help. I have tried recetting the ECU but doesnt seem to make any difference. Hope someone can help.

right think you need to more detail in the meaning of reduction in power

Reduction in power description
 

The reduction in power is across the complete rev range. It is probably a 30% reduction. It is not an agressive reduction in power i.e. like a dump valve. The car runs as normal then all of a sudden when you try to accelerate it has a reduction in power and doesnt clear itself until you switch the ignition off then back on again. Unfortunately as mentioned earlier this ignition trick doesnt work anymore. I have also had a problem with the mass air flow sensor (which was replaced) but when it was playing up the engine was very rough under load - so I think this is a different problem? Hope this description helps. Thank you.

do you have any mods it might be you need to remap the car, if you have a decat and induction kit and havent remapped it that could be the propblem and also check if your induction kit is the right one for the car

Have you got a boost gauge? What boost pressure are you running?

I had the same problem on my old Cavaliar, it turned out to be the oxygen sensor.