my car when accelerating, changes its tone like its missing between about 2000-4000rpm like its detonating, kinda clears and power feels like its surging but not joltiong arround,but it falls on its face after 5000rpm and ive replaced the knock sensor since old one was cracked allover and it went away completely then came back, i have ran injector cleaner through it and at first, before this issue i got 28mpg then to 20mph then 24 when filled with premium gas. I reasearched but no luck, its a swap from a 92 legacy. it doesn't always do this but usually disconnecting knock sensor while its running fixes for about 3 starts of so, before i replaced the knock sensor , when starting sometimes i had to hold it to the floor while cranking it and it ran on two cylinders until i drive or rev it up, then goes normal. Im just confused and trying to work out the bugs, so ideas will be appreciated .

i just recently had this problem, check your injectors. when this happened to me i ended up replacing the knock sensor, throttle positioning, fuel filter, and o2 before i finally figured out one of the injectors was shot.

from the sounds of it you might have more than one out.

Edited June 9, 201213 yr by mikaleda

i had that off and on for a while.

i thought it might have been a piece of dirt

running through, and they told me it was an injector

at autozone (there was a check engine code) but it

took care of itself.

have you changed gas filter lately?

dang now that i think of it, the filter hasn't been changed since i got the car over 4k miles ago. I replaced 1and 3 injectors with used ones as they completly quit, but it took a while for the injectors to work too as there wasn't a difference right away and the engine jolted all arround on two cylinders, may try a tps today as its like 5 bucks, possibly 2,4 injectors and fuel filter

carefull messing with injectors as it will dump feul into piston and could hydroilic engine and bend rod i do come across dead injectors from time to time but never more than one and they are ushaly water or rust damaged

i would do a filter before i messed with the tps. when you replace the filter run some more injector cleaner through it it again. running injector cleaner through a dirty filter will do nothing for your injectors.

ok ill try filter and cleaner