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Forester Occasionally Stalls at Stops

('03-'05) 
29K views 13 replies 9 participants last post by  Eagan01 
#1 · (Edited)
This car belongs to a friend of mine

2006 Forester
N/A (Not Turbo)
Automatic
26,000 Miles
Drive By Wire
NO CHECK ENGINE LIGHT
Never been in any accidents
Never had any major work (pretty much just oil changes)

Problem:
The car will die when you come to a complete stop. It is very infrequent. Sometimes it’ll do it 4 times in a row. Sometimes it’ll go a few days without stalling. But on average I’d say every 1 in 10 stops it’ll stall out.

Stalling:
You don’t even realize the engine turned off. There is no shudder, no bouncing idle, nothing. The needle just continues it decent down the tach until it touches the bottom peg. It starts right back up though.

Conditions:
Have no effect. The engine can be cold or hot. Outside temp doesn’t matter either (40’s to 70’s). Has done it after backing out of the garage as well as coming to a stop light after a 50 mile commute. You can come to a quick stop or a slow one (not idle slow of course). When left in Neutral it has never stalled.

Tests:
Took it to the dealership and they cleaned the fuel system/throttle body. That didn’t work so they said nothings wrong with it and therefore, nothing they can do to fix it. I’ve plugged in my computer and read O2, RPM’s, fuel pressure, throttle position, coolant temp, intake temp, etc. and I’m not an expert on what I should be seeing but everything appears to be functioning as it should.

Vehicle Condition:
Very well taken care of. Low mileage. Apart from stalling the car runs like it’s new. No engine bogging or rough shifts.

I personally think it’s something with the transmission, not sure what. Could be something sticking, some debris stuck, or a sensor/solenoid going out. I dunno, I’m not real good with the inner workings of an automatic. I do not think it’s engine related. I’m kind of leaning towards replacing the valve body but as you can see by me posting this for help, I’m not real sure. Planning on a transmission flush before winter gets here.


I’ve also read online about bad 02 sensors causing this but never throw a code, as well as a bad MAF, coolant temp sensor, torque converter lockup solenoid, etc. But a few things lean me away from those. 1) The mileage/year 2) How infrequent the problem is. 3) The computer read out (unless a sensor is sending bad info, but how can you tell? Just change it?)

Thanks for sticking through a long read. Anyone have any ideas or further testing I can do?
 
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#2 ·
aha i have your answer

This happened on my friends skyline.
2 things: check the Air Flow Meter is working by having the car running and while in idle disconnect the sensor. it will be on the intake normally near to the throttle sensor. dont get these mixed up. when disconnected the ecu will revert to its base line and you will hear a change in the engine. if you dont hear a change it could mean that the sensor is broken. these are cheap anyway. secondly if your foz is turbo it could also be a boost leak. meaning somewhere between your turbo and intake is not sealed and after coming to a stop your car is starving for oxygen. Cant see it being anything else, pm me how you get on with this

nate
 
#6 · (Edited)
You guys, I appologize. I made a mistake and feel like an idiot.

It's a 2006 and it's Drive By Wire.

I'll change what I can to the initial post.

As far as cleaning goes. Subaru put through their pressurized bottle of BK44 or whatever that stuff is called. It went straight into the where the fuel line connects at the intake manifold (they by passed the tank/pump and all that). I cleaned the MAF and throttle body. He's put in fuel injector/system cleaner straight into the tank a few times. He's switch to higher octane fuel (90 is the highest we get).

The car will run with the MAF unplugged. I plugged it back in while running and the car died. I've gotten mixed advice online to whether or not that means the MAF is bad or good, so I decided to go with good, maybe next time the coin will land on tails (kidding).

But all kidding aside, I've been around subaru's for about 7 years, I've changed transmissions, suspensions, brakes, rear diff's, head gaskets, engines, timing belts, turbo's, installed auto starts (on a manual - I was very impressed with myself), but this has really got me stumped.

I appriciate feed back so far, thank you guys. Correct me if I'm wrong but because I put the wrong year in, nothing from above applies to Drive By Wire right? Is there anything else I can try?

Thanks again
 
#8 ·
Intermittent failures are really difficult to track down. Sounds like you need to maybe track values of the MAF on OBD. If you can get access to one, note what thevalues are wen it does idle and maybe then get a value when it stalls.

GM's had this issue (stalling at idle) with dirty EGR valves. I don't know if Subaru uses an EGR valve. Ij suspect they do.

Maybe bite the bullet and replace the MAF
 
#9 ·
Hi subydaddy,

I have got the same model and year car you have. My car acts exactly same as yours. And it is worse when you stop the car on sloped ground. 80% of the time the engine will stall. You can have a test on your car. I have been check a lot of components on the engine, and couldn't fix the problem. I think it can be the auto transmission.
 
#11 ·
Test the ignition coil.

Test the ignition coil. I believe this car has a DIS ignition system -waste spark. The primary side should be 0.5 to 2.0 OHMs. I am not sure about the secondary. Check the repair manual. If it checks out OK have a shop check it with an Oscilloscope. In fact, any good shop that knows how to use an Oscilloscope, there are many that do not, can qualify all of the sensors. You might not "catch" the ignition coil in the act of failing. However, you can eliminate other possible suspects without expensively replacing them. A car that stalls is dangerous.
 
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