2007 Outback stalling

[89Ru]

2007 Outback 2.5L 5-speed wagon, 130 k miles. Running rough, stumbling at low speeds and stalling at idle when rolling to stops. Power is normal, I can't tell any differences on the highway. Was getting cylinder misfire codes. Just put on new NGK spark plug wires, swapped all NGK spark plugs and both O2 sensors with spares and no change.  Idles slow, rough and stalls when it warms up. No misfire or any other codes since pulling the battery for plug swap. Carbon dust on plugs and O2 sensors, like its running rich? I have a virtually identical 2008 2.5L Outback auto to swap parts from. Where to start? Has aftermarket knock sensor, and both O2 sensors are aftermarket Denso. O2 sensors checked out ok with an ohm meter. 

[el_freddo]

Check out the idle air control valve. On my sister’s EJ251 it can cause stalling issues as it’s either not operating properly or the rubber bung on the end isn’t sealing properly as it should. Or it’s dirty, causing less air than intended to get through when needed. 

Cheers 

Bennie 

[montana tom]

I agree, check the IAC valve.   It is different between automatics and 5 speeds.

For your 5 speed I would remove it and carefully clean inside with a q-tip and alcohol.

I've had about a 50% success with that.  New ones are not cheap.  

[89Ru]

Ok will check that out. Good to know I can't just swap it over from the auto.

[89Ru]

Where is the IAC? It's not listed in my FSM.  Idle control appears to be electronic, controlled by the ECM.

From Factory manual, troubleshooting guide

1. Engine stalls during idling.

1) Manifold absolute pressure sensor

2) Mass air flow and intake air temperature sensor

3) Ignition parts (*1)

4) Engine coolant temperature sensor (*2)

5) Crankshaft position sensor (*3)

6) Camshaft position sensor (*3)

7) Fuel injection parts (*4)

 

2. Rough idling

1) Manifold absolute pressure sensor

2) Mass air flow and intake air temperature sensor

3) Engine coolant temperature sensor (*2)

4) Ignition parts (*1)

5) Air intake system (*5)

6) Fuel injection parts (*4)

7) Electronic throttle control

8) Crankshaft position sensor (*3)

9) Camshaft position sensor (*3)

10) Oxygen sensor

11) Fuel pump and fuel pump relay

12) EGR valve

 

3. Engine does not return to idle.

1) Engine coolant temperature sensor

2) Electronic throttle control

3) Manifold absolute pressure sensor

4) Mass air flow and intake air temperature sensor

5) EGR valve

[idosubaru]

It’s always very close to the throttle body, on those I think it’s attached right on top drivers side of the throttle body. Small plunger, two bolts.  There’s a couple varieties over the years, I could be confused. 

Cleaning sometimes works but if you’re uncertain and have a parts car with usable part that’s an easier “test”.

If you replaced parts with no change in symptoms then that basically rules out any of those parts even if, for example, an aftermarket knock sensor isn’t ideal or as good as OEM.  I’ve installed 5-10 aftermarket knock sensors with no issues.

Edited December 26, 2020 by idosubaru

[el_freddo]

If you have electronic throttle control you might not have an idle air control valve as the ECU should be able to manipulate the throttle for appropriate idle speed. 

It could be worth checking to see if the throttle body is clean. 

All the best 

Bennie

[1 Lucky Texan]

Is this car an Outback Sport?

Imprezas had dbw in '07, not sure when legacy outback got it. dbw does not have IACV, the ecu holds the throttle open for idle air or something I think.

any CEL codes stored? early DBW had some bad throttle pedal asemblies - pr maybe the car has lost its zero calibration?

exhaust smell rich? gas smell?

Edited December 27, 2020 by 1 Lucky Texan

[brus brother]

Here's the link to sequence for relearning/recalibration. Or this link.

If you are still having trouble and haven't cleaned the throttle body, follow the link below.

Here's a link for cleaning the throttle body.

 

 

Edited December 27, 2020 by brus brother

[89Ru]

All makes sense. Car is an Outback wagon 2.5L manual, base model. No new codes so far. Just idles like crap. Will clean throttle body and perform the idle relearn sequence. Videos are helpful and show how much crud can build up on the backside of the throttle blade. I typed up the two procedures, without changes, credits to original author, to save some time.

1. Clean throttle body (disconnect battery now if you plan to do the idle relearn procedure)
   1. From time to time you will need to clean your throttle body. Over time carbon and oil deposits form on the throttle blade and bore and restrict airflow. This procedure is more important to do regularly on 05+ models with electric throttle bodies. These vehicles use the throttle body alone to regulate idle speed and don't use an Idle Air Control valve or servo.
   2. Remove airbox. Use a lint free rag, old toothbrush, brake cleaner, can open the throttle body blade manually to get behind it, use a long handled brush. For additional cleaning, take apart. Clamp cooling lines off with rubber hose pliers and remove. Disconnect electrical connections. Remove four rear facing bolts. Clean backside of throttle blade. Reassemble. Can reuse throttle body gasket but should have one on hand anyway. On reassembly, retorque bolts x4 to 6 ft lbs.
2. Execute idle relearn procedure
   1. Disconnect battery for 10-30 min, and reconnect
   2. Turn key on for 10-15 seconds, throttle body motor will go through sweep procedure
   3. Start engine w/o any additional electrical loads (radio, A/C, blower, etc)
   4. Idle engine for 10 minutes w/o any loads, do not touch accelerator pedal
   5. Shut engine off, leave key in off position for 20 seconds
   6. Turn key to on position for 10-15 seconds
   7. Start engine, idle for 5 minutes
   8. Turn off engine, wait 20 seconds
   9. Test drive, idle relearn complete

 

[brus brother]

Before you go breaking anything... least is always best.

See if just executing the relearn procedure solves your issues. Just a few minutes of your time and a few turns of the key, no wrenches or grease rags needed.

Then if problem still exists, ask someone to hold your ankles as you dive in deeper.

I ran into the same issue on my 05 OB Auto. I cleared the P0420 persistent code and forgot the patience part of relearning. Hopped in the car and drove away. Until I did the relearn, ran poorly and stalled as you describe.

You did say you disconnected the battery (same as me clearing codes with a code reader) so you may have also not allowed the normal relearn sequence?

Edited December 27, 2020 by brus brother

[89Ru]

Not detecting any fuel vapors as far I can tell. I'm sure I didn't allow the proper idle relearn sequence after disconnecting the battery for the plug change. I wonder if this is something that has to be done every time the battery is disconnected?

Today I cleaned the throttle body, see pic of thick gunk on intake side of the throttle blade after separating the throttle body from the intake. Probably saved me from a future problem. Did the idle relearn procedure as written, ran rough as before, like its missing, as the idle slowed down as the engine warmed up. Didn't touch the gas at all, per procedure. Didn't stall. On the 5 minute idle, got misfire codes in cylinders 1,2 and 3. With it running rough/misfiring, I'm assuming that the ECM relearned the idle as best as it can with another problem on board. I may have to repeat this step. So for now, its back to the troubleshooting chart above. I recall the previous occasions of stalling happened after I touched the gas, which dropped the rpm's. Probably some time late next week I'll start swapping parts from the 2008 auto, starting with the MAF and manifold pressure sensor because they are easier to change, and the coil pack.  I have a freeze frame from my new code reader that doesn't appear like anything is obviously broken, to my untrained eye.

[el_freddo]

That’s a crazy amount of gunk on that throttle body! 

Have you tried running a can of upper engine cleaner through the engine? Follow the instructions to a T and keep the revs up as you spray the remainder of the bottle in. 

I’d say you have some very dirty intake valves - the back side of them. This could be causing issues with the air fuel mixture entering the cylinder. 

What sort of compression are you getting on each cylinder? 

Cheers 

Bennie

[1 Lucky Texan]

6 hours ago, el_freddo said:

That’s a crazy amount of gunk on that throttle body! 

Have you tried running a can of upper engine cleaner through the engine? Follow the instructions to a T and keep the revs up as you spray the remainder of the bottle in. 

I’d say you have some very dirty intake valves - the back side of them. This could be causing issues with the air fuel mixture entering the cylinder. 

What sort of compression are you getting on each cylinder? 

Cheers 

Bennie

 

yeah, I can't help wondering what issue has been going on to lead to that? Bad PCV valve? or bad temp sensor or knock sensor or ??? throwing off the fueling/ignition for a long time???

wonder what the valves look like?

maybe that SeaFoam spray with the u-turn nozzle could help here?

Edited December 28, 2020 by 1 Lucky Texan

[89Ru]

Compression test 20k miles ago while diagnosing clogged cat. Has some oil filler cap blowby, but adequate power.

cylinder 1 205 psi
cylinder 2 180 psi
cylinder 3 165 psi
cylinder 4 185 psi

Pcv replaced with oem a year ago, was aftermarket. Has newer aftermarket knock sensor that I installed to try to correct preignition, that didn't help. Still knocking under load. Coolant temps report at low 180's typically on highway. I can try to seafoam the intake, will lookup the process. How to control the rpm while sucking cleaner in the intake since this car has no throttle cable on the intake like 2004 and older?

 

[el_freddo]

7 hours ago, 89Ru said:

How to control the rpm while sucking cleaner in the intake since this car has no throttle cable on the intake like 2004 and older?

Someone has a foot on the throttle to hold revs where they’re needed? 

Cheers 

Bennie

[89Ru]

Ran seafoam into the open intake. 

1. Remove the air box/snorkel, after disconnecting the MAF connector.
2. Run the engine until warm, CEL will illuminate for MAF code(s).
3. Spray 1/2 can of sea foam into the intake, slowly
4. The engine will slow with each spray, I did this step at idle. Probably done better with someone on the gas pedal.
5. Engine stalled when I sprayed a bit much.
6. Let sit for 5-30 minutes
7. Start engine - for me would not run well, or at all, until I reconnected the airbox.
8. With airbox reconnected, clear CEL codes, and run at 2k rpm until tailpipe smoke clears

So the car still idles low and rough. I also put a whole bottle in the gas tank. Test drive revealed worse preignition, probably from extra carbon nasties in the combustion chamber, that might have gotten a bit better at the end of the drive. I might repeat seafoam spray and/or get the kit from Subaru: SOA868V9341, containing three items: Top Engine Cleaner, Fuel Injection cleaner, Throttle Plate and Induction Cleaner

Of note, the car didn't run any different with the MAF (and airbox) disconnected, still idled rough during the entire seafoam step. So perhaps that eliminates the MAF as a suspect. Probably worth changing the oil after all is done to remove any contaminants that find their way into the crankcase. 

[89Ru]

Did another can of Seafoam spray into the intake, this time by the book, so I left the airbox on the entire time and used the hose with the 180 degree turn that came the can, that loops over the lip into the throttle body so the airbox can stay put. Spray took about 10 minutes while running the engine at 1400 rpm. Let it sit for 20 minutes. No codes. Didn't run any better afterwards, after letting all the smoke out. On the test drive, saw four pending cylinder misfires, and a new pending code P0172 "system too rich" that didn't make it to an official code flagged, instead two misfire codes were flagged cyl 3 and 4.  Oh and I got the same pre ignition noise that seemed to improve by the drive end. Had changed the knock sensor for a spare, that didn't seem to make a difference. This is getting downright interesting. Got the intake cleaner combo kit from Subaru but I kind of doubt it is going to make much difference now. Coolant temp cycles up to 212-214 until the fans turn on while sitting in neutral, and down to normal operating temps on the road. 

Going to have to dig into the P0172 code to see why this is running rich. Never had this code before. Could it be from a leak in the air snorkel from the seafoam tube?  

[brus brother]

Are you the original owner or did you inherit a headache?

Check coil? Are the wires routing correctly? Any arcing if you mist water around coil or wires?

Did you do/change anything that precipitated the current status?

Swapping parts is good diagnostic technique IF you are sure they are working donors.

[1 Lucky Texan]

cyls 3 and 4 share half the coil.....

[89Ru]

14 hours ago, brus brother said:

Are you the original owner or did you inherit a headache?  

Have owned it for about 2.5 years. Have had a boatload of trouble with this ride, more than any other subie, its my training vehicle I like to call it, for wrenching. Bought it from a manager of an auto shop. Never will do that again. He sold me a real creampuff.

 

Check coil? Are the wires routing correctly? Any arcing if you mist water around coil or wires?

Has new wires, not touching each other. Going to swap coils hopefully today.

 

Did you do/change anything that precipitated the current status?

Dunno. Not that I'm aware of.  Has a lot of new parts over the past 2.5 years including entire exhaust system and both O2 sensors, mainly due to clogged 2nd cat and rusty flanges, and head gaskets. Pistons were covered in flaky crispy carbon as I recall. I have pics. That work was done 1-2 years ago which fixed the intended problems. It's never run right since I bought it, with regard to pre-ignition. So maybe it's been running rich for a long time, creating havoc. 

 

Swapping parts is good diagnostic technique IF you are sure they are working donors.

I swapped out the knock sensor a while back to "fix" the pre ignition under load (was also having cyl 3 and 4 misfires), without changes, so presume it's a functional sensor although I don't recall explicit "knock sensing" as in flagging CEL and pulling back the timing, unless it happens without operator knowledge, either with the old sensor ( I think OEM, or the new aftermarket one).  So perhaps both are bad.

 

[brus brother]

Try swapping coil and verify that some yutz didn't "misplace" the wires leading to cylinders firing out of order.

Probably less noticeable on a V8 than on a 4 banger where fire would be shooting out of your nostrils.

[89Ru]

2 hours ago, brus brother said:

Try swapping coil and verify that some yutz didn't "misplace" the wires leading to cylinders firing out of order.

Probably less noticeable on a V8 than on a 4 banger where fire would be shooting out of your nostrils.

No fire from any orifices thankfully. Wires were correctly installed. Coil swap from a 2008 (my daughter's car) didn't change anything except some glaring looks from her teenage face haha. Car still searching for idle speed all over 600-800 rpm and rough.  The MAF is different so couldn't swap that. So I pulled the MAP connector from the throttle body and started it and it flagged a CEL immediately, BUT, NO MORE WANDERING IDLE!

Pulled the MAP sensor from the '08, swapped it, reset codes, and voila, its purring like a kitten. I live essentially in a flat plain without major altitude changes so I may be able to run like this until I can get a replacement. Maybe some vaporized crud in the intake found its way into the sensor. Sprayed some electrical contact cleaner into the MAP sensor cavity, but maybe best to replace with OEM?

[brus brother]

well done!

[idosubaru]

4 hours ago, 89Ru said:

No fire from any orifices thankfully. Wires were correctly installed. Coil swap from a 2008 (my daughter's car) didn't change anything except some glaring looks from her teenage face haha. Car still searching for idle speed all over 600-800 rpm and rough.  The MAF is different so couldn't swap that. So I pulled the MAP connector from the throttle body and started it and it flagged a CEL immediately, BUT, NO MORE WANDERING IDLE!

Pulled the MAP sensor from the '08, swapped it, reset codes, and voila, its purring like a kitten. I live essentially in a flat plain without major altitude changes so I may be able to run like this until I can get a replacement. Maybe some vaporized crud in the intake found its way into the sensor. Sprayed some electrical contact cleaner into the MAP sensor cavity, but maybe best to replace with OEM?

That’s awesome.  I’ve never seen MAP sensor failure so I have no idea.  They seem rare, I’d install a used OEM one.  Glad you knocked it out.

Thanks heaps for posting back. My Tribeca is running poorly with no codes - it’s drivable but slow pedal response and lack of power and poor gas mileage.  Hate to guess but I might look into the MAP since it’s so easy.