Hi i got a 1994 wrx import and i having a problem with it. It keeps reving up to 2000rpm then to 1500rpm then back to 1000rpm but it never goes under 1000rpm. when driving soom times when you floor it she some times back pops and finds a flat spot can anyone help me please many thanks ricky.

 

i know this sounds very unlikely but a loose clip or hose and even a small crack in the intercooler pipe underneath can cause this , basically a vacuum leak or a bad inlet manifold gasket , they can also come from the up pipe or manifold but i doubt this .
failing these then i would say the maf or the idle control valve , usually u can tell if u rev it it bogs at first then revs freely sort off also when the revs are coming down after reving it they stop at 2000 then return to 1000 eventually , basically ur engine is sucking in unmetered air somewhere after the maf sensor as i siad failing this its more than likeley the maf , hope this helps but bear in mind even a small small leak can cause these symptoms sometimes so be aware also sumtimes the jubilees can gouge the hoses if tightened to much even the gaskets for the intercooler underneath and the bolts that hold these pipes , the worst ive seen is a leak in the intercooler itsself but this is quite rare but can happen , spray wd40 all over the intercooler or another liquid preferably as wd40's a bit messy if the intercooler is leaking u should see a distortion or bubling and even a normall idle as the liquid clogs the air leak not allowing unmetered air past the leak ?

 

just for backup check the pcv valve is ok , underneath the manifold at the back also the throttle body gasket

 

Just out of interest, what fuel do you use mate? I've got a WRX import too. Jan 97.

 

hi mate i put unleaded in it by mistake i use 97ron most of the time. many thanks ricky

 

hi mate thank you for getting back to me. You are wright i could be sat at the lights and she will rev to 2000rpm then go back to 1000rpm then under load she will have a little miss fire but still pull like a rocket but still revs high. many thanks ricky

 

if u sort the idle problem due to it being a vac leak then u still get the miss at the top end then that will be one of ure coils or plugs for def causing the miss , most likely the miss will go away when you sort the leak but sometimes they can be a pain to find , worst case mate that i have seen before is a bad headgasket the only way to check this is to empty the water in the engine by pulling the bottom rad hose and start the car for 1 minute no more than this and rev the car , if it revs ok and no bad idle or misses a beat as i like to say then more than likely ur gettin water into the combustion chamber but only try this as a last resort as this can also mean a crack in the block and is definately end of the line experiment stuff as in if all else fails as i have only ever seen this happen 1nce before and is not a recomended way of doing it but it does work

 

sorry not the only way to check for a bad head gasket , was in a bit of a rush not thinkin there . by doing it this way just saves u getting the h/g done to find out its not that causing the problem that you particularly have ,

i would defo say that u have a vacum leak though

 

if u had this problem as well u wouldnt pull like a rocket either so just discard my last post about the head and block mate .

 

hi mate i took the car to subaru and they plugged it in and found a fault they said it could be my maf or my idle control valve but dont no which one to change first. the maf is £240 new and the idle control valve is £280

 

i have a maf and idle control valve mate , not sure of the mafs condition but ill give u that for nout also i will give u 2 idle control vlaves both to fit earlier 93 - 96 scoobs 25 posted for these 3 ( 1x maf but not sure of working conditions of it but free anyway , and 2x idle control valves at least i think ive got two ?? lol )

 

the icv's definately work for sure so if u install 1 then u know its ur maf mate ?

 

the icv's are normally 20 each from breakers in my experience dealing with andy at subaru spares in hebden bridge ? so i would say its a good'un lol 60% sure that the maf works but as i said not entirely ?

 

sounds like a good deal for me mate contact you tomorrow bud many thanks ricky.