steven bass

Sorry for posting about this again but....

My 95 wrx idles at 1500 and running rich. Ive cleaned the iacv with brake cleaner, changed the o2 sensor for a brand new one. Ive put a multimeter on the maf, tps, and iacv and all seems ok. I can adjust the tps and iacv to lower the revs but its rough and still at 1200. Ive ohms tested the ecu temp sensor and that drops ok. I cant find a vacuum leak and dont think i have one as the idle is stable and doesnt fluctuate.

Any suggestions?

Can the sensors still be faulty even tho the volt and ohms tests are good?

Also when i take off the iacv (mine is on intake manifold and not on TB) but leave the connector on, i turn the ignition on....is the valve meant to be fully open or shut? Or do i watch the valve for movement while someone turns the key on n off?

spuker1

Could it be the knock sensor? I have a faulty one in my car and sometimes it reckons that my engine is about to stall when it isn't so it makes it rev at idle up to 2000-2500rpm sometimes even but as you say it's stable 'normal' idle. That wouldn't explain running rich though...

steven bass

Well i can find things on google that say a knock sensor can cause lower mpg so i guess running rich but i cant find anything that says it causes a high idle, maybe a low idle but not high.

spuker1

I can tell you first hand that my knock sensor makes my car idle high and sometimes it makes the engine drop revs very slowly on deceleration. That could be it. Put your ECU into service mode (or whatever mode it is when you connect those two black connectors over your footwell) and check if it doesn't throw any errors. If it's 22 it's your knock sensor.

steven bass

Yh i did that and got 32....o2 sensor. Since that got replaced i have no ecu codes at all. Done the blacks.. then greens.. then both together. No codes at all. When decelerating it pops like mad so defo running rich. Plus my exhaust is black at the back.

Would like to know how the iacv is supposed to act though when unbolted. Not sure what is meant to happen to the valve when the ignition is turned on?!

Sometimes tho...when i stop the revs have now and again dropped to 800 (lumpy n struggling) then raises to 1500 over n over again until i tap the accelerator. This has only happend 3 or 4 times.

tjmatt

iTrader: (1)

Have you tried adjusting the screw on the throttle stop to see if its just that the throttle isn't being allowed to shut enough? The idle control valve might be at its minimum setting but still give a high idle if the throttle isn't allowed to close enough. The rich issue *may* be something else. Really you need live ssm diagnostics to see if the ecu has set the idle control valve fully shut when its got a high hot idle. It would also help diagnose the rich condition, if indeed it is rich.

tjmatt

iTrader: (1)

You updated just as I posted, it does sound like its rich if its doing that. To be honest nasty idles are quite symptomatic of failing MAF. You could try cleaning but would be worth borrowing a known good one of someone to test really. You can't test a failing MAF unless you know exactly what voltages you would expect for any given load, and I can't imagine you have the voltmeter hooked up as you drive along.

tjmatt

iTrader: (1)

Does it idle or drive better with the MAF disconnected? (only off boost)

steven bass

yeh ive loosened the throttle cable right off with no improvement. The car just cuts out with the MAF disconnected, so this as i gather means its ok?! I found some volt results somewhere and checked my MAF to them. I cant remember exactly what they where but im sure on idle it should read 0.5v then up so much with certain throttle. Maybe this is false info? not sure.

steven bass

sorry i was wrong about volts. its 4.7 on idle.....[url]http://www.rs25.com/forums/f190/t111628-throttle-position-sensor.html ...this is the link. I just checked mine and its 4.7 on idle.

steven bass

well ive had my iacv off again! i left the connector on and turned the ignition. the valve inside moved but it just twitched, it didnt move to open or closed and stayed there, as i say it twitched. Does this mean its knackered?

scooby1982

iTrader: (4)

Couple of things have you checked thg you have the correct icv on your car mate as mayb someone changed it before you bought it? (Depending on how long you had car obvs) also my uk ( not wrx) when you disconnect maf it will start and still idle ok and drive do this could be possible that yours is faulty perhaps??

steven bass

yes mate ive checked it, its the correct valve. I did read just now that on these iacv's, if you undo the two screws holding on the sensor to the valve and then twist (like i did) then the idle should go up or down depending, but always correct itself to the right place so back to good idle. Mine doesnt do this, mine just stays up or down depending which way i twist. does anyone know if that statement is correct?

Im suprised at your car running with the maf disconnected as ive read it should cut out?! I'll have to double check that

madscoob

iTrader: (3)

sounds like unmetered air , i had same symptoms it was a air leak between maf and turbo

steven bass

well after cleaning both throttle body and iacv again, reinstalled as everything was before and my idle went up to 2500rpm, i had to turn the iacv all the way anti clockwise to get the revs down and now getting fault code for iacv. Why would this happen after just cleaning it? all pipes are good with no leaks?! Just wish i had another scoob around to get the iacv off n try it on mine before i part with more money

steven bass

Well put a working iacv on today. No change! The guy i saw is a mechanic n only drives scoobies. He seems to think that when the new dials got put in (from kph to mph) the rpm counter spring was probably bent! Because he thinks it idles ok to listen to. The engine does sound like it n hes not the first to say it. That doesnt explain running rich n the car occasionaly dying when clutch pushed in. It also needs a few second revs to keep it from stalling on cold start

steven bass

Been for an mot and car is running "EXTREMELY" rich. I Cant remember the readings n dont have a print out but i remember the guy saying something is meant to be below 200 n mines 1000! I have changed the iacv twice, once for a yellow label n no different. The maf has been cleaned n the car cuts out when unplugged so is there something else wrong like ecu?! Will a vac leak cause crazy over fuelling?

steven bass

Also i noticed when i had my exhaust manifold off, 2 of the exhaust ports/holes on the head were sooty. Standing at the front looking at the car its the two on the right