Attention GTB/B4 gurus! GTB Idle/stalling problems

[Guest]

Hi guys, my 2001 GTB e-tune wagon has a weird idle problem.

When its cold its fine, but as it warms it hunts real bad and goes up and down until it goes so low it stalls.

It does this most of the time its warm, but sometimes it behaves 'normally' and idles ok at 850rpm ish.

Also, it covers the back of itself in black soot it runs so rich, and it is low on power and has a shakey power delivery.

Would AFM be a most likely cause? Or oxygen sensor?

I have cleaned idle controller out, and the codes the ECU pulls are 'twin turbo system' and 'differential pressure sensor' which I dont believe are idle related. I have checked everywhere for vaccum leaks and found none.

Any ideas where to start??

[Hailz]

Hmmm if thats the codes it's comming up with take it to your nearest Subaru authorised workshop I'd say as from what I've heard that code is not a good one to have, good luck!

[log1call]

Those codes could be set if the mixture is so far out that the motor can't rev properly, so I'd try and figure/cure the idle problem before I fixed that code.

How is the air filter?

Can you check your fuel pressure and fuel pressure regulator?

Can you use a digital multimeter(voltmeter), to check the O2 sensor? It's easy if you have and know how to use a multimeter.

[Guest]

check your vacume lines on the manifold make shore northing has come off. and i also second on the O2 sensor.. then would be checking the AFM.

[D-Style]

sounds like problem I had, check Temp sensor, (cheapest out of a new O2 and AFM)

[Guest]

How do you check the AFM ? and O2 sensor ? I aslo have a simular problem. But mine just wont idle when cold or hot, just misses , but sweet when driving

[log1call]

You test an O2 sensor by connecting a volt gauge to it, while it's still attached/plugged in to the car and the car is warm and running. The easiest way to do that is to solder two wires to two pins, then poke the pins inot the back of the connector where the sensor connects to the wiring loom of the car. When the motor is warm and idling the voltage should be constantly fluctuating between about 100 and 900 millivolts. If everything is in good order the voltage will really only swing between about 300 and 700, but they can go to the higher figures too. The really important thing is that it's fluctuating. The fluctuating is it detecting a rich mixture and telling the ecu to lean the mixture, then it detects a lean mixture and tells the ecu to richen it again, and so it goes on. If it's just at one end of the range there is no feed-back happening or there is something wrong preventing the mixture from changing... like air leaks or flooding because of faulty fuel pressure regulator for instance.

The MAf should have about one volt on two of it's wires when it's idling. It goes up near five volts at revs but you can't really check that without connecting a laptop to it. If it's one volt at idle it will probably be right.

There are specs and test procedures in a pdf called "diagnostics" here...

http://tinyurl.com/yktuyro

[Guest]

thanks for your help and advice. I will test the o2 sensor, however would that come up on the codes if it was faulty?

im thinking of trying a mates idel control solenoid in the car to see if it makes a difference to its behaviour.

also, D-style, what temp sensor are you reffering to? water temp?

cheers