White smoke + rough idle and hesitation.

[evljat]

I feel like I’m making another one of these threads every week…

The car is a V3 STI The last few times I’ve driven my car I’ve noticed that the idle has been a bit rough. It wasn’t fluctuating but I could feel vibrations through the steering wheel. I didn’t think much about this.

Today everything turned to shit. I went to grab something from the local dairy and the car was running fine until then. When I started it up it wouldn’t idle, going up 1500 rpm then dropping right down. I let it set there for a while hoping that it would steady but then whitish/bluish smoke started puffing out.

The car was hesitating and wouldn’t accelerate properly but I could hear the turbo spooling. It began to puff black smoke if I gave it too much throttle. After about 3000 rpm it would run fine and have no hesitations. Every time I approached lights the idle would go crazy again and it starts puffing whitish smoke.

Also, the car hasn’t been boosting right for a few weeks. It hits about 9 psi then slowly goes up to 11. It has a Greddy Type S boost controller.

So in summary:

• idle fluctuating and rough

• Smoke puffing out at idle

• Hesitation

• Low vacuum at idle

Could it be a bad AFM or a vac leak?

Cheers guys, hopefully it’s something simple.

[94 Leone]

Looks like bov leak symptoms.

[slystiguy]

have you got an afm you can swap for a test?

Have you plugged the black plugs under dash in to check for error codes?

[evljat]

I don\'t have a spare afm.

I\'m getting error code 23 Air flow meter or circuit (exc. Justy); Pressure sensor (Justy). (http://www.troublecodes.net/Subaru/)

I\'ll be taking it down to Highbrooke Automotive first thing tomorrow to get it checked out. I spoke to Alex (I think) over the phone and he thinks its the AFM also.

Weird thing is that I took it for a drive around my home after disconnecting the AFM and it drove fine. And when I plugged the afm back in it drove fine for a short while too. Then started acting up again.

[slystiguy]

pretty sure it will be the AFM, someone can confirm? White smoke sounds odd though... Possibly a leaking IACV as well? Might be worth the 5$ gasket to check and clean/replace. The more I read the more it sounds like a combination of problems. Low vac could be a boost leak and possibly the reason for the idle problems. Generally with these old cars its either

coils

afm

fuel pump

boost leak/intake leak/exhaust leak

what colour afm and what area you in? maybe someone locally can source something for you for cheap?

[94 Leone]

White smoke is overfuelling iirc. AFM or if on boost, boost leak: and maybe o2 sensor aswell, as they can still be reading: but giving poor information: causing it to overfuel: thus white smoke. So new AFM, clear codes, if still white smoke (off boost) replace o2 sensor if white smoke is on boost: check for a turbo-intercooler-inlet leak, I.e. tighten up hose clamps etc.

[Guest]

Coils normally noticed under load when they get bad enough at idle also. Try restting the codes before you replace afm or take it anywhere see if it clears itself up.

[evljat]

I\'m a bit unsure on how to reset the codes. Do I just plug in both the green and black connectors and keep the speed above 11km/h?

[Guest]

Classic (JECS) ECU Reset

Ensure engine is at normal operating temperature, turn engine off

Locate the two ECU connectors, located under the steering column and consist of a black plastic male and female connector, and a green male female connector

With the ignition OFF connect black to black and green to green.

Turn on ignition, do not start the engine, depress the accelerator pedal to full throttle, then return it to the half-throttle position and hold for a few seconds, and then release

Engine Check lamp turns on

Start engine and then drive for at least one minute, keeping road speed above 11 Km/h.

ECU is now re-set.

At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be professionally checked for necessary repairs.

Stop the car and turn off the engine.

Disconnect the black and green connectors.

Job complete

[font=]Pressure sensor /

Pressure exchange solenoid[font=]Abnormal signal from pressure sensor or

pressure exchange solenoid inoperative

[evljat]

Thanks for that I\'ll give it a go in the morning.

[Timmah]

 evljat said:

Weird thing is that I took it for a drive around my home after disconnecting the AFM and it drove fine. And when I plugged the afm back in it drove fine for a short while too. Then started acting up again.

So with AFM unplugged, all symptoms appear to stop? Money is on AFM being the primary cause.

[rex-leggy]

Ya cars running like a ass becase thats what it does when a codes logged... Limp mode for lack of a better term.

Its you car tring to save its self from self implosion.

Get it fixed and dont thrash it in this state