Hi guys, not been on here for a while but i'm back now as I've Just bought impreza number 2. I'm having problems getting it to idle it'S a 99 turbo with full serv history from subaru. I've fitted new plugs and cleaned out the idle air control valve but the idle still rises and falls. The engine managment light hasn't been on and she drives fine appart from the poor idle. Any ideas???

 

Water temp sensor?
Caused dodgy idle on mine (my93wrx)

 

Thanx m8 do you know of any way of checking the coolant sensor?

 

Have you checked the Maf sensor?

Prone to failure on my 99/00....

 

No not checked maf any ideas what readings i should be getting?

 

Lambda sensor - mine does this and i know my lambda sensor needs replacing

 

Unfortunately i don't know how to check the sensor i took mine to my local specialist and they put in a new one as a test and it was fine after that.

 

SOUNDS LIKE MAF SENSOR, do the revs go up and down on their own?

 

Failing MAF. About £80 for the actual sensor from Subaru.

If it's failing, the check engine light won't come on......


Only know this through my own experiences. (many thanks to Tony at the time for helping out!! )

Dan

 

Most likely the MAF .... get it changed!!

These should be included in the service schedule on MY99/00 cars .... can fail at any time, and the consequences can be anything from poor idling to blown engine!!

£75 from Extreme Scoobies for an original part and 10mins to fit!

 

Drive off boost till you get it sorted, failing mafs usually cause the car to run lean, possibly leading to disasterous consequences if you put your foot down.

Ns04

 

At first glance I thought this thread was some sort of SOS from Eric Idle!

 

If the problem is only at idle and off-boost it is most likely a lambda/02 sensor that is buggered. yOU WILL need to buy a new one. The lambda sensor will only make a difference off boost.

Otherwise it could be the MAF sensor.

 

Its quoted at the top though that its idle only .... car drives fine otherwise .... would that not make it the MAF??

I thought, when driving, the MAF affects WOT and the lambda partial throttle .... but the idle would most likely be affected by the MAF??

Either way though, I would change the MAF anyway, particularly if it has never (or recently) been changed .... £75 isnt a lot for a bit of peace of mind!!

 

AFAIK, closed loop fueling i.e. off boost, is regulated by Lambda, open loop fueling i.e. on-boost, not just WOT, is regulated by MAF. One of the symptoms of a dodgy maf is an erratic idle though, sometimes you also get a slight hesitation at around 4k rpm. The car may be "going particularly strongly" with a failed maf, due to it running lean. If you have any suspicion about your maf get it to a specialist to check it and your lamda (takes 5mins) The maf is a known weakness with the MY99/00 and can cause engine failure. It's simply not worth the risk.

Ns04

 

Thanx guys managed to order a maf sensor this afternoon. Spoke to the guy from subaru and they were really helpfull so its coming tomorrow and will keep you posted
Cheers again

 

dont suppose there is an aftermarket dump valve fitted is there?

 

No car is totaly standard not had a chance to do any mods want to get it running right first

 

ok mate, had one fitted to mine, it caused irratic idle

 

Same problem on my MY99 a while back
A new MAF cured it
Now i have a spare for the next time

 

I've had the idling problem on both a MY99 Impreza and a MY01 Forester, both resolved with a new MAF sensor.

 

That sounds good makes me feel a bit better splashing out £70 on a stab in the dark

 

if your fitting it yourself you will need a security torx screwdriver, cant remember the size off the top of my head, possibly T-10

Mine did this for a while, and was the MAF, the easiest way to check if its the MAF is with the engine running, unplug the MAF, if it continues with erratic idle it is the MAF, if the engine cuts out then the MAF is ok

Lambda is usually loss in power as well, at least mine was, but gradual over a period of a few months, Lambdas afaik should be changed every 3 years, as they have a finite life, again from what I can remember

(this is *Sonic* btw lol)

 

Hi guys. fitted the new maf and she runs like dream now thanks to all who helped.

 

dan