KareenaBaby

hi there guys i would like your help to find out why my revs are being funny. i have a version 3 sti with an air filter, dump valve & exhaust. recently after driving the car when i turn it off & turn it back on the revs sit normal just below 1000rpm but then suddenly it drops all the way down to 0.1 but the car does not stall. but after that it drives perfectly.

any idea what could be causing the issue? ive been told it may be the maf.

THANKS xx

APIDavid

iTrader: (4)

Maf is certainly the best guess. Try to borrow one off a mate with a good car the same as yours before buying, as they aren't cheap and if it isn't the MAF you'll have wasted a couple of hundred quid.

Where are you in the country ? And how technical minded are you? As you can do an on board ECu check yourself if you have some knowledge.

David Api

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KareenaBaby

i am in south london, well i work as an IT technician lol so i am abit technical minded i suppose. if the ecu check thing is easy then im sure i could give it a shot.

how does it work btw?

thanks

myblackwrx

iTrader: (1)

Check the voltage across the MAF.
Ecu check can be done manually look here Scoobypedia | Trusted knowledge for everything Subaru | Scoobypedia / Scoobypedia under the 'ECU' heading or unplug the MAF whilst the car is running and it should stall (not a foolproof test though)

KareenaBaby

thank you very much babe,

so if the car does not stall that means the maf is faulty. my boyfriend told me it could be cleaned with card cleaner, is that worth doing?

KareenaBaby

sorry wer abouts on the engine bay is the ICV located? what does it look like

myblackwrx

iTrader: (1)

Personally i'v never cleaned a MAF so can't say if it works or not even if yit does work i think it would be only temporary but not sure.

MAF stall = faulty

This is what it looks like but on your car (mine is an early wrx) it's somewhere else (not helpful sorry)

KareenaBaby

that is help ful thank u very much, i also came across a helpful guide on JGM site

KareenaBaby

the thing is the car does not shake while that happens or no engine light comes on. this happened twice in one day. before that the car had no issues, i thought i should ask all the kind people on here just to be on the safe side.

KareenaBaby

what do u reckon guys ICV or MAF

99greenwagon

iTrader: (39)

hummmmmmmmmmmmmmm let me think

myblackwrx

iTrader: (1)

it could be an air leak though.
How long has it done it for?
Although we can suggest everything internet diagnosis is not the best way to find out what's wrong.
Try and clean 1 sensor first and see if it sorts it if not clean the other.

www.slowboy-racing.co.uk these guys are in London so may be worth paying them a visit

KareenaBaby

it only happened yesterday. i went out stopped my car turned it off, got back to my car started it and the car idled at normal then it made its way down. but bearing in mind the car did not stall shake etc. this only happened on two ocassions.

oye & i was on reserve tank with about 7miles left in the tank if that helps

APIDavid

iTrader: (4)

OK, NEVER run a Subaru low on fuel you'll do heaps of damage to the engine try to trat 1/4 as empty and never let it go below there.

The MAF is not usually troublesome on that age of car. I'd go for the ICV which is simple enough to pull to bits, clean and replace. It is a mechanical thing that gets gummed up with carbon, so a wire brush job.

If you look at the marks on the icv adjuster where the screws clamp it to the inlet manifold you will have a shiny spot . Just make sure you put it back on to the shiny spot when you refit it.

If still a bit off for tickover then move it a very small amount up or down the scale and you'll see /hear the idle change.

David APi

myblackwrx

iTrader: (1)

May i ask how?

APIDavid

iTrader: (4)

The one ended fuel rail system tends to starve no.3 cylinder at the best of times. lf you have low fuel, you pick up air instead of fuel and it makes the No. 3 cylinder problem worse.

Driving it hard on low fuel is Russian roulette. It is not surprising therefore, if l tell you that most of the cars that come in here with busted engines have no fuel in them. We most often have to put a tenner or twenty quid of fuel in just to road test them when we're finished.

David

myblackwrx

iTrader: (1)

Thank you very much for that.

KareenaBaby

thank you very much david, i done the maf test and the car did stall. im going to have a go at cleaning the icv.

by the way david do u map?