Just got a little 5dr 5 speed a couple days ago thats fun to drive...above 2500 rpm. I have no CEL but when accelerating from a stop, its really slow and sluggish but right when it hits 2500 exactly, its like the boost kicks in or somethings and it takes off. If you shift into the next gear and the starting RPM for that next gear is bellow 2500 then the car will bog down and then take off again once it reaches 2500. If when you shift into the next gear, your starting RPM for that next gear is like 2600+ then there is no hesitation in acceleration and everything is smooth. Someone told me to reset the ECU so I just went out and unhooked the negative and I'll hook it back up in the morning. 

From my experience there isn't any real power till you hit 4k+ then its like oh so that's what its supposed to be like.

 

If you suspect something is wrong I would start with a good fuel system cleaning. I would start by changing the fuel filter and running some good fuel injector cleaner for a couple tanks.

 

I also just changed my gear oil with motul 300 and I may be imaging things, but it seems like my low end has gotten more responsive lately like it has less drag. That could be wishful thinking though.

Edited December 1, 201510 yr by mikaleda

define slow and sluggish. What engine do you have? does it feel like a misfire?

what year/engine?

 

1.  read the OBD codes - it can have a pending code without triggering a CEL

2.  does the CEL actually work?

3.  check timing belt for looseness, tensioner mechanism and alignment (though i doubt you'd have great performance at high RPM if that was the problem)

4.  check for vacuum leak - spray starting fluid around engine bay - if there's a leak the engine will rev

4.  knock sensor sounds likely but usually gives a check engine light and EJ18's that come in some impreza's don't have a knock sensor