Legacy idle plus more issues

[kris_pran]

Hey guys

Ive come across a problem on a mates 99 B4 automatic that was purchased not long ago.

The problem was first discovered when we got in to start the car after a drive 2 hours ago which went completely fine. When we started it the revs dropped from 1500rpm to 800rpm then to 300rpm, sometimes it stalled completely.

After a few searches on the internet and over here as well regarding similar symptoms i decided to do these things.

1. Check AFM for buildup of dirt.

2. Check TPS

3. Check ICV

4. Check for leaks/ lose vacuum hoses

The AFM looked fine and didn\'t have any buildup of dirt of any sort, regardless we gave it a wack of contact cleaner. After checking and cleaning the above three sensors/valves we fired up the car and it ran perfect for 2 mins just as the problem was never there then the revs started to drop to 200-300rpm again and this time black smoke started pouring out of the exhaust. This lead me to the conclusion that it might be something to do with air or spark.

The next day we pulled the spark plugs out and it didn\'t seem to be worn out, because it was on a sunday at 5pm we didn\'t get the chance to purchase replacement plugs so we cleaned the current ones with petrol and tested the leads and plugs that a healthy spark was being produced before putting everything back together. Started it up and ended up being the same as the day before low revs/stalling at idle/black smoke.

Next day we put in a brand new genuine afm and reset the ecu. Started it up and noticed the black smoke coming from the exhaust before was gone but the idle issue remained. Now ive noticed the idle literally sits at 100-300rpm and the motor does not jerk at all as someone would expect from such low idle levels although it does stall at times. So we took it for a moderate drive and the turbo is really hesitant to come on boost and jerks really hard at around 3000ish rpm. We immediately stopped testing because we didn\'t want to risk blowing anything lol.

The next day i started it up hoping for some magical thing might have happened that the car went back to normal lol when the key is turned to on there is a noise that sounds like an aftermarket fuel pump (current car is completely stock) coming from somewhere above the centre diff. the car hesitates while trying to rev it the slightest bit and even if i get it to 2000rpm and held it there the revs would just drop by itself and come back up and drop and come back up again even though i kept the pedal at the same place.

Its really confusing because now i honestly have no idea what might be causing the issue, could it be something to do with the fuel delivery? Car always ran on bp98

Also is there a check engine light on these model legacys because i cannot see one when the dash lights up before starting.

Any input would be appreciated

[tebbyj]

Hi,

It could be the fuel pump or fuel preasure regulator might be the cause as black smoke usually indicates to rich mixture.

Do you know anyone with a OBD II scanner? Really need to get it on one and see what that puts out.

Also does the idle change according to engine temp? ie: Idles fine when cold but then goes lumpy once warmed up? If so would be checking your Front O2 sensor voltage, the ECU reliles heavily on this sesnor to calcualte mixture once engine is warm, It should be Fluctating between 0.1-0.9v ish. They often get worn out and carboned up and need replacing, just dont go to subaru for one theyll charge you an arm and a leg, a Bosch universal one will work just fine.

[soopersubaru]

possible injector fault...Staying open at times.

[Joker]

check your coolant temp sensor, I think that was the cause of my last Auto that was stalling

[kris_pran]

Yea ive got a hold off a Obd2 connection with the free ssm software but unfortunately the software responds back with \'\'no or invalid answer from ecu\'\'. Checked the connection again and the obd connection is hooked up correctly. ???

The black smoke i mentioned has gone away since the new afm was installed.

tebbyj - Yea the idle does stay normal when its cold but once the temperature gauge gets to normal and a bit of slight revving the revs go down to 300rpm.

[tebbyj]

I dont know about the ssm software or how it works so i cant help you there sorry.

You can pull the codes manually by connecting the black terminals under the dash together, there are how to\'s all over the net.

You can check the O2 sensor buy finding its connector (from memory its the bottom one on the bank of connections between battery and the washer bottle) unplug it and see if the car idles/runs better, and to double check back probe the wires and check for the 0.1-1v signal.

Bosch recommends replacing the O2 sensor every 50-80,000ks anyway. :

[kris_pran]

Ok so the scanner has started working and it came up with TPS code.

Took it out cleaned it, spring seems to be working fine as well. While putting it back in i noticed you could adjust from left to right while the screws are intact. I dont know how to adjust these in back correctly and if its just a bit out of place its makes a buzzing sound so I\'ve positioned it so that the sound doesn\'t come on when the key is turned to ON.

Checked for codes again and nothing came up. but while i shift the gear to D i can hear that buzzing noise coming from the TPS for a quick 2-3seconds then it goes away.

While driving it at 30km/h+ it suddenly feels like someone has applied the brake and the car starts slowing down and revs start falling by itself despite me not removing my foot from the accelerator pedal and then it comes back on again. Happens repeatedly

Has this got something to do with the TPS not adjusted properly?

The idle issue has been fixed i guess revs stay constantly at 500-600ish.

[Marky]

The TPS adjustment is very fiddly and yes is quite likely the cause of the symptoms you are describing

I can\'t remember the voltages you are meant to see, from memory you want it to be putting out about 0.45V at idle?

If it is out of alignment the ECU thinks the throttle is open when it\'s not... or closed when it\'s open, and tries to drive to suit - goes all horribly wrong.

To be blunt I can\'t google it for you right now, just do a quick search for "subaru B4 TPS adjustment" or something and you\'ll find it

[kris_pran]

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing1.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing2.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg

These are what i found after a quick search. Could someone give me the green light whether this is the correct procedure for the car so i can go ahead and conduct a test.