Here goes.
Attempted my first service on my 93wrx, oil pugs & filter, nothing to ambitious.
job in itself went ok with lots of reading and searching on here (cheers peeps)

fired her up to find it runs like a bag of sh1te!

back on here bit more searching,
CEl check = nackerd Maf
new MAF = still runs like a bag of
CEL check = all good
changed coil packs

still no good !

symptoms..
lousy idle between 1000 and nearly stalling
but whilst accelerating nothing at all picks up sweet, but try and maintain a constant speed lurching and juddery

pops & bangs like a good un on de-sel

so any ideas much appreciated, my next thought is perhaps lambda but don't want to just keep buying bits on the off chance
also have a small hole in the down pipe right at the back (don't think this would cause the problem though.

so chuck us you thoughts and cheers in advance..

 

start the car, then whilst started.... unplug the maf sensor...

if the car totally concs out, the problem may be elsewhere!

i still think it seems like a maf problem.

 

Why do people insist on unpluging a sensor while it is talking to the ecu! did you replace maf new if not could be faulty to check maf properly try one of another car (same maf) as dodgy mafs do not always cel also there is sometimes a patern to a failing maf as in one that was not totally dead but fooling ecu(running lean)after replacing maf then ended up replacing lambda too do a search sure there are a few have same probs

 

If car was running ok before service ,i'd double check your plugs and coil packs

 

Maybe just check plugs noticed you changed coil packs !

 

i had same kind of problem it was showing a maf fault so i got a second hand one from a subaru breakers,put it on and had exactly the same problem. I ended up buying a new maf from Roger Clark Motorsport £200 and the car is sweet again.

 

an air leak??

 

Perhaps you damaged a plug when fitting? If all you done was plugs an filter, it's got to be in that area.

Worth checking!

 

I've had the plugs back out and checked gaps and nipples all ok
done the unplug whilst running and the car died didn't with old one (but yes it is a second hand 1 from Grade A.

an air leak??
where and how do i check had a good look at all the pipes and conections seem ok

 

just outta interest which plugs you put in it mate,just took some blitz irridiums out of mine and put ngk in and its made the world of difference-wont be buying irridium again.

 

NGK platinum.

 

ecu re-set?

 

I think so, done the bit with the wires but don't know how that works so disconected the battery tonight and try again tomorrow.

 

Oh right, just re-read 1st post.... Your saying its only the idle that is affected and it actually accelerates fine, yeah.

In that case i would agree with reno, more than likely knocked a small pipe off somewhere.

Try keeping it running at the lowest possibe rpm and listen for vacuum hiss.

 

Start by checking that the plug leads are connected in the right sequence.
With the engine running then look for a lead not properly connected or with leakage.
If that draws a blank, start checking all the vacum pipework looking for a pipe off or a leak.
Chances are you have disturbed something during the service and it just takes patience and systematic examination to find it.
If all that fails, let it tick over and falter for a minute or two and remove the plugs again to ID the problem cylinder to narrow your search/investigation.

 

I did all the plugs and coil packs 1 by 1 so as not to mix them up

spent a hour with my head under the bonnet this morning listening and feeling round pipes and still no joy

so must still be fualty Maf i think

 

Sounds like an air leak.I assume youve had the air box offf check and double check all the vacum pipes are re connected.