scoobylav

I seem to have a problem occassionally after a hard long run. If I have been driving hard and come to a fairly sudden stop (i.e Traffic Lights) When the revs drop to idle sometimes they drop to around 500RPM, judging by the tacho. Too low. It does not hunt for idle just drops to that level and stays there unless I blip the throttle then it will return to normal.

MY97 - Any ideas, the car runs perfectly apart from this.

timmyjmy93wrx

I have same problem with my93 wrx!
i'm not having much luck with mine at the moment, nothings going right!
not found cause yet, think its the idle control valve thing replace or needs cleaning.
Hopefully someone will reply to help!

drb5

iTrader: (4)

do either of you have a atmospheric dv fitted? or could it be a MAF problem?

scoobylav

I have atmospheric dv and an induction kit (k&N)

[Edited by scoobylav - 1/19/2004 12:04:23 PM]

timmyjmy93wrx

I had a bailey but took it off but do have a K&N induction kit
Have tried using original airbox, still does it, but MAF seems OK and is clean!

scoobylav

timmy do you have an afr gauge fitted ??

timmyjmy93wrx

No but it is on the list as soon as possible!

scoobylav

Anyone any other ideas ??

drb5

iTrader: (4)

dunno why my last post never went up, but scoobylav...can u try replacing the standard dv? if it doesn't help, both of you could try getting a hold of another MAF to see if it makes a difference

scoobylav

I don't think it will be the dv as that has been fitted for years. The induction kit has only been fitted for about 6 months. The problem has only reared its head twice first time just after christmas and then again at the weekend.

drb5

iTrader: (4)

no pipes missing from it anywhere?

Mal26

Mine (1995wrx) does exactly the same. My garage checked the lamda(oxygen) sensor which they said was on the way out. I now have purchased a new one but not fitted yet but I would say lamda is your culprit!

scoobylav

It does appear to run rich most of the time i.e lots of pops and bangs from the rear.

drb5

iTrader: (4)

the pops and bangs have nothing to do with the lambda sensor, but the induction kit and atmospheric dv.

Dark Blue Mark

If your 02 (lambda sensor) is shot, you will probably have crap fuel consumption, as your engine uses this sensor off boost.

If it was MY99 / 00 then your MAF is the most likely culprit. Pre 99 MAF's are pretty good it wouls seem, so I would look elsewhere.

1st check is the throttle position sensor, which is on the throttle body. With the ignition on, but engine off, you need to check the output from the sensor. Disconnect the sensor plug, and stick a multimeter on it. Middle pin is earth, and use the outer one as the signal. Set the multimeter to Ohms.

You should get about 0 when the pedal is at rest, and about 5 when flat on the floor, and it should be linear. 2 man job as someone has to push the pedal

Also spay some WD all over the trottle spring area for good measure.


Next culprit is the Idle valve. Its on the right hand side, just down from the intercooler, and has A B C written on the lid, which is a cream colour. There's a pipe running to it from the airbox. Try and squirt some brake cleaner in there with someone giving the car 3k revs. Or you could use both hands and pull the throttle cable

If you do a search you can find out how to strip it down.

Do an ECU fault check too

MB

Dark Blue Mark

DRB5,

The pops could well be caused by an overfuel from the 02 sensor.

But a DV will also cause that on lift off.

MB

drb5

iTrader: (4)

ah, cool

scoobylav

Thanks for those ideas MB I will have a play at the weekend and see what happens. Maybe a stupid question but how do I do an ECU fault check ??

Dark Blue Mark

Use the search facility and type "ecu fault codes"

The check / reset is quite easy.

MB

StevieB

Scoobylav,

Just to confirm what DBM has said about Throttle position sensor..... I asked a similar question on here a week or so ago where I suspected the MAF with an idle problem with CEL a couple of times. Select monitor traced this to Throttle position sensor which DBM also suggested

Steve (MY98)

Dark Blue Mark

Steve,

Did you replace yours or just clean it? Is it fixed?

MB

StevieB

DBM,

Only had it diagnosed on Select Monitor so far and an ECU reset. Doubt this will clear the underlying fault .....so will clean and check with your instructions above

Thanks
Steve

Dark Blue Mark

Ok,

If you do a search, there are better instructions for actually dismantling the offending sensors. You have to be careful you dont move any adjusters when removing them, it would seem. I had a look at the weekend, and the intercooler needs to come off to get at them, but thats a very quick job.

MB

scoobylav

MB - I have been having a read up on ECU fault reading and resets. It appears to me that if I have a fault showing on the ECU I would have had the CEL light on at some point ?? I haven't at all not even a flicker !!!

Thanks for your help so far can you confirm the above ??

Dark Blue Mark

Possibly - or maybe not. I had a CEL that only came on for a few seconds while I was sat in traffic. If id been pushing it, I wouldn't have noticed. There may be ones on there from before you owned it too. Worth checking what they are, then resetting it to see if they re-appear a week or so later.

The codes are a little tricky to work out at first, as its a bit like morse code. But after about 5 goes at it you will work them out! Best to use a bit of paper and use morse code type symbols

MB

STI_TYPE_RA

get your ecu mapped properly and sort out your ignition timing