stalling when stopped... dealer says there's no problem?!

For a few months now I've been having a problem with my 2008 automatic legacy (65k) stalling when rolling up to a parking spot, stop light, intersection, whatever. At first a few months back it would shudder pretty violently when I started to roll up to a stop, but didn't stall. Now it just full out stalls, sometimes several times a day. When it doesn't, it feels like it's on the verge of stalling. It seems to be much worst right at start up when the car is still cold, and really bad when the weather is cold. A few nights ago it stalled three times in one trip. It was pretty chilly (15ish degrees) and there was a lot of stopping and starting (city driving). I can avoid the problem if I shift into neutral before coming to a stop, but obviously that's not a solution. A few weeks back I went to pull into busy traffic and the damn thing just shut off... nearly right in front of oncoming cars. So it's definitely dangerous.

 

I'm unsure if these two other issues are related or not, but the car also seems to have a difficult time accelerating... it will speed up, but when it shifts, I can feel the car slow, then speed back up again... like it's working harder to get into the next gear.

Again, I'm not sure if this is related, but it also surges really violently in certain circumstances. If I come to a stop really quickly, then try to accelerate quickly, the gas won't respond for a second or two, then it will LAUNCH forward REALLY roughly - so hard that it will throw my head back against the headrest. It's extremely scary, to be honest. During all of this, the CEL doesn't come on.

 

I took it to the dealership where I got it. They said the computer showed no problems. They test drove it and said nothing was wrong when they drove it, so there's no problem - please fork over $200 to NOT diagnose a problem and NOT fix it.

 

For background, I got into a bad accident about six months ago that crushed my radiator, AC, headlight, hood, radiator support, etc. The shop that "fixed" it did a $%#^ing awful job (steel hood instead of aluminum, no paint primer so the paint is peeling off everywhere, headlight from taiwan held together with DOUBLE STICK TAPE) so I'm suing them for the $4,500 I paid, so I honestly have no confidence that these geniuses didn't f**k something up that is now causing these problems, given I NEVER had these issues before the accident and they started almost immediately after I got the car back. I doubt that helps much but I feel like it's pertinent... and if these morons did something to cause this problem, they're going to pay for it. :mad:

 

Anybody have any ideas? I am taking it to a shop soon but want to suggest what might be wrong... I thought a vacuum leak, but who knows. I have lost all confidence all mechanics given the completely terrible service I've gotten from the last three, including the dealership, so I really want to just tell the next shop, "please check this, this, this and this."

throttle position sensor (TPS), the car may not be acting to the amount of pedal your applying, or reacting inappropriately. No CEL's is odd though. There must be stored codes in there.....

could it be something in the transmission, like the torque converter got jarred during the collision? I'm not really 100% sure what the torque converter does, but it seems like maybe it's something physical as opposed to electrical, which is why they can't get a code. But it is BS to charge you just to say, nah your car is fine.....

 

Good Luck solving the problem...

Start with a MAF cleaning. Then check that there aren't any hose loose between the MAF and throttle.

 

Considering that you have had morons under the hood you should really check that the hoses are correctly routed. Swapping two hoses isn't good.

 

It can of course be a simple thing too - like the PCV valve stuck open. Not everything that goes wrong with a car causes a CEL or a code.

 

And bad cam timing can also be the cause. If you have twin cam heads then it's not easy to get it right on all cams combined with the crank. I did it on a STi engine outside the car and it was bad enough. Be aware that cam position sensors goes on intake cams but not on exhaust cams so if an exhaust cam is off it can be the cause - and not give you any code.

Were you able to replicate the problem for the dealership? It's not really diagnostic, but does a hard reset aka disconnecting the battery for a bit help?

Were you able to replicate the problem for the dealership? It's not really diagnostic, but does a hard reset aka disconnecting the battery for a bit help?

 

 

The dealership claimed they could not replicate the problem and had no issues driving the car... they kept it overnight in order to start it up cold and said even then they didn't find anything. They said they sprayed some coil with water (I don't remember the exact terms they used) because they thought moisture might be causing the problem but no dice. $200 bucks for nothing... As for your hard reset suggestion, I have not tried that. What might that do?

I have had very similar issues with my "new to me" '08 LGT with about 54K miles. I took it to the dealership and was told that the transmission fluid needed to be changed. I did that myself (with genuine Subie fluid). The transmission shifted a little smoother, but it still wanted to die at idle and was very sluggish after each upshift. Last week I pulled the MAF wondering "what if" and low and behold: it was filthy. I cleaned it with some CRC Mass Air Flow cleaner and the problem was much better, but not perfect. This weekend I cleaned the throttle body, which was also quite dirty, and ran a tankfull of seafoam through it. It's driving like new now, idling smoothly and accelerating properly. For what it's worth, mine never threw the first code either.

I have had very similar issues with my "new to me" '08 LGT with about 54K miles. I took it to the dealership and was told that the transmission fluid needed to be changed. I did that myself (with genuine Subie fluid). The transmission shifted a little smoother, but it still wanted to die at idle and was very sluggish after each upshift. Last week I pulled the MAF wondering "what if" and low and behold: it was filthy. I cleaned it with some CRC Mass Air Flow cleaner and the problem was much better, but not perfect. This weekend I cleaned the throttle body, which was also quite dirty, and ran a tankfull of seafoam through it. It's driving like new now, idling smoothly and accelerating properly. For what it's worth, mine never threw the first code either.

 

Thanks for your suggestions. I'm going to check the transmission fluid first thing when I get out of work today. I'm really hoping it's a simple fix like that, or a MAF needing a good clean. I have an appt. at a shop but scheduled it for next week to see if I can't figure this out myself.

 

This is probably a stupid question, but what is seafoam..?

The dealership claimed they could not replicate the problem and had no issues driving the car... they kept it overnight in order to start it up cold and said even then they didn't find anything. They said they sprayed some coil with water (I don't remember the exact terms they used) because they thought moisture might be causing the problem but no dice. $200 bucks for nothing... As for your hard reset suggestion, I have not tried that. What might that do?

 

I had an 05 impreza that would occasionally have no throttle response, and a very weird idle. Disconnecting the battery to allow the computer to reset would fix the problem temporarily which indicated a computer problem and not a mechanical problem.

i have a similar issue with my mt though. its not stalling but violently shakes like its about to die.

This is probably a stupid question, but what is seafoam..?

 

Not stupid at all. We're all on these forums to learn right? Seafoam is an engine oil / fuel additive that supposedly cleans gum, varnish, and carbon deposits. Like most of these products, I tend to view it as "snake oil" but it is highly recommended on most automotive forums. In my limited use of it, I've put in the "can't hurt" category. You can find more info by doing a search but basically you add a can to a tankful of gas to clean the fuel delivery and combustion components of the engine. It can also be added to the crankcase or delivered directly into the downstream side of the throttle body. Use as directed, don't take my word for it :-)

Not stupid at all. We're all on these forums to learn right? Seafoam is an engine oil / fuel additive that supposedly cleans gum, varnish, and carbon deposits. Like most of these products, I tend to view it as "snake oil" but it is highly recommended on most automotive forums. In my limited use of it, I've put in the "can't hurt" category. You can find more info by doing a search but basically you add a can to a tankful of gas to clean the fuel delivery and combustion components of the engine. It can also be added to the crankcase or delivered directly into the downstream side of the throttle body. Use as directed, don't take my word for it :-)

 

Thanks for the explanation. I'll give it a try... maybe it won't do anything but it's worth giving it a shot!

I had an 05 impreza that would occasionally have no throttle response, and a very weird idle. Disconnecting the battery to allow the computer to reset would fix the problem temporarily which indicated a computer problem and not a mechanical problem.

 

 

D/c the battery resets the ECU, the ECU then goes into learning mode until ~200miles of driving. During this time the ECU is very lenient to changes, so the car may feel 'fixed' until it's done collecting data from all the sensors, and your driving style, throttle response etc...

I was thinking torque converter too. If it locks at low speed, it will cause a stall situation.

D/c the battery resets the ECU, the ECU then goes into learning mode until ~200miles of driving. During this time the ECU is very lenient to changes, so the car may feel 'fixed' until it's done collecting data from all the sensors, and your driving style, throttle response etc...

 

The problem would go away for a few thousand miles, it turned out to be a computer problem that the dealer fixed on their second try... This doesn't sound the same, but subaru's computer systems are some of the pickiest I have experienced.

Check your BOV and make sure it is re-circulating and not venting to atmosphere. Make sure the hose clamps are on right and the recirc hose isn't damaged.

my car also idles a bit rough when warming up from a cold start, doesn't stall though. :/ drives fine besides the idle until it's fully warmed up.

samething happened to my car...ive looked at everything and even got a mechanic to check for a leak and no leak whatsoever...after weeks of looking, it was the air filter, once i changed it and got the correct one and reset the battery everything was good. The air filter i had previous had just a bit smaller measurement all around not by much but enough to have effect which was releasing too much air was getting into the system...casuing the car to work harder...hope it helps let me know if you have other questions!! good luck!

i have an 06 gt 5eat by the way

Just started experiencing these idling problems as well, and I'm really glad that this forum is available. I too have an 06 5EAT but with a reflashed ECU. I have an extended warranty but I'm thinking, should I start cleaning the MAF first, or should I just take it to the dealer and hope that they won't blame the whole issue on the reflash? Suggestions?

Just started experiencing these idling problems as well, and I'm really glad that this forum is available. I too have an 06 5EAT but with a reflashed ECU. I have an extended warranty but I'm thinking, should I start cleaning the MAF first, or should I just take it to the dealer and hope that they won't blame the whole issue on the reflash? Suggestions?

 

The dealer cannot detect the aftermarket flash unless they send the ecu to SOA- which they won't do. They may reflash it though- to a newer subaru ecu version if the program, Subaru Service Manager, pulls up an update for your VIN when the tech connects them.

Oil Control Valves, check those first.

Oil Control Valves, check those first.

 

Thanks for the replies. I guess I was lucky. I brought it to the workshop by my place, they sprayed some CRC cleaner stuff (purpose was to clean and check for leaks/bubbling), and found one of the hoses that was loose. We didn't go through the whole ordeal of trying to figure out the purpose of that hose, but it was one of those hoses that connect just below the factory top mount intercooler. There was no clamp on this hose and I don't think it fell off because the hose was not disconnected when we found it, just not "all the way in". Total damage ended up being $60 as opposed to who know how much at the dealership and my car is idling way smoother now, like when I just got it. Perhaps the hose had been loose for a while now.

Mine was having rough idle issues during warm up at cold temps. I found a forum relating the issue to the o-rings between the intake and tumbler valves. After replacing them, its been running smooth.

 

http://legacygt.com/forums/showthread.php/diy-rough-idle-cold-start-cold-temps-lgt-07-09-155325.html

arms akimbo? chuck?

 

first off, do you have a turbo Legacy? or is it non turbo? (hoodscoop / no hoodscoop). also, is this your first winter with the car?

 

there are some threads around with people that have the same issue as you. I used to have the problem (car stalls completely when coming to stop right after starting it up and it's cold out) but it hasn't showed up this year. I think I may have had an intake leak when the issue was happening to me.

 

If you can find those threads that this was discussed in, there were a number of solutions people tried. Some worked for some people, but not for others. This is definitely a real problem, though, and Subaru has denied it to everyone who tried to take it to the dealer.