Rough idle and stalling constantly 05 LGT

My 05 Legacy GT with the DOHC 5 speed manual has been running pretty rough lately whenever i start it and TRY to drive it as soon as i give it any throttle and let off it will stutter and die but will start right back up like nothing is wrong. I plugged in my OBD2 scanner and it is pulling up a bunch of misfire codes.

Here is a list of what i have replaced so far,

- new 02 sensors

- new timing belt

- new turbo

- new clutch

- new spark plugs

 

the only thing that i can think of that may be causing this issue is possibly the injectors? ik that the injectors on the 05 generation were known to have some problems.

 

or possibly the coil packs? the car has only 120,000 miles on it but it sat for a few years in my neighbors yard before i purchased it.

 

Any advice is greatly appreciated im pretty new to subaru and am not very experienced with them and have no idea what a lot of the common problems are.

Can you please provide a full list of DTCs?

Do you have access to live data, preferably with BtSsm?

I was having a very similar issue with my car too. Rough idle, stalling when returning to idle, ect. It turned out to be the OCV's (Oil Control Valve). Essentially, the engine uses oil pressure to open 2 valves (one on each side of the motor) to change the valve timing to be more aggressive for the top end. If one of these valves gets stuck open, the engine is trying to idle on an aggressive timing, and stutters and stalls. Here are a couple other threads about the OCV's:

http://legacygt.com/forums/showthread.php/p0011-p0021-missfire-ocv-oil-flow-control-valve-141880.html?t=141880&highlight=ocv

http://legacygt.com/forums/showpost.php?p=1943328&postcount=8

It might not be your issue, but it sounds awfully familiar to me.

Hope this helps!

The simple things first. Clean MAF, clean throttle body, check/replace donut gaskets, make sure all hoses are on properly, check PCV, check valve clearance (sucks), check fuel pressure, make sure the timing belt is correctly installed - one or two teeth off can cause problems.

 

Coil problems usually locates the misfires to one cylinder.

 

Get the injectors cleaned and checked, uneven injector flow can burn valves.

And make sure that you got the right spark plugs. The turbo engines have a longer thread than the NA engine plugs.

Have you taken your intercooler off recently? If so, perhaps your throttlebody to intercooler hose did not reseat properly.

 

If you haven't taken your I/C off recently, then perhaps you have a tear in that coupler.

So, i tried to start it again today to try to diagnose this problem or problems. While it was running i noticed that i can smell unused fuel coming out of the exhaust like it is running very rich or something and i did go back in and double check all of the intercooler hoses etc and they were all correct fully seated. Along with when i replaced the spark plugs i made sure to get the ngk iridium ones that were for the DOHC. And as for the oil control valve i have been doing some research but im not really sure what this valve is for or how it would effect the engine in the way mine is currently running.

Can you list the codes that the scanner is displaying?

P0302, P0301, P0304 im just receiving a bunch of misfire codes and have been getting these codes since ive owned the car even though i have no idea what could be causing them to fire so inconsistently because when i replaces the spark plugs and cleared the codes and drove the car for a bit they all come back and then the motor began to run like shit as usual.

So, i tried to start it again today to try to diagnose this problem or problems. While it was running i noticed that i can smell unused fuel coming out of the exhaust like it is running very rich or something and i did go back in and double check all of the intercooler hoses etc and they were all correct fully seated. Along with when i replaced the spark plugs i made sure to get the ngk iridium ones that were for the DOHC. And as for the oil control valve i have been doing some research but im not really sure what this valve is for or how it would effect the engine in the way mine is currently running.

What exact spark plugs did you buy though? Did the end of the part number have "-11"? If so, the gap is wrong.

 

Did you plug the coil packs in fully? White connectors to front cylinders and black connectors to back cylinders?

Diagnosing this problem requires live data - fuel trims, misfire counts at various RPM ranges, etc. A great tool is BtSsm with an OBDLink dongle. Total cost is not much more than a set of pointlessly replaced spark plugs. Get that and post your learned values, and the folks here can point you in the right direction.

A cheaper and full-featured tool is FreeSSM with a $10 VAG-COM cable from eBay.

What exact spark plugs did you buy though? Did the end of the part number have "-11"? If so, the gap is wrong.

 

If it's just the gap it can be adjusted, but the turbo engines also have a different thread length and that's a lot worse if it's wrong.

If it's just the gap it can be adjusted, but the turbo engines also have a different thread length and that's a lot worse if it's wrong.

Agreed. That's why it would be nice if the OP gave a part number.

I have an OBD2 scanner, however i left it at my place in Colorado where im going to school. I did do some maintenance to it today and here is what i have found based off what i have heard on this thread so far,

 

As for the OCV i pulled both of them and checked them with a 12V source and they engage and disengage freely and smoothly along with they were coated in good clean oil, no dirt or anything stuck to them. So i ruled those out of the picture.

 

Then i moved to the spark plugs and pulled the ones i put in to check which kind i used and the part number on them is NGK 7913. I even checked the gap on them all just to be sure that they were all correct and they were all at the correct .030".

 

After that i reset the ECU to try to get it to start so i could look around/listen for odd noises and it fired right up and purred like a kitten at first. But when i try to give it any throttle is sounds like its going to cut out the instant i press on the accelerator but then it will start to go and it will rev no higher than 3000 rpms along with the turbo was sounding like it was spooling up and then blowing off randomly like it needs to be adjusted to the throttle or something. Im at a loss on what to do at this point.

Rag or other obstruction in your inlet?

 

Edit: nvm should have read earlier posts

That sounds like you need to do the idle relearn. Plenty of info about that. It is something that needs to be done every time the ECU is reset or battery is pulled.

I've had this issue for the last year or so. I've tried quite a few things, cleaning the throttle body, retune, etc. Anyways over the weekend I replaced my Power Steering Pump. During which I noticed my positive battery terminal was pretty heavily corroded - I spent some time with a wire brush/coke can and cleaned it up and re-seated it. Also replaced the air filter at the same time. Anyways now when I do long pull and pop it in neutral - no cut off. Even when its cold. Before this you could watch the RPMs bounce off 0 and studder trying to get up to idle.

So maybe it was a relearn that helped, not sure but I wanted to share here b/c it's a pretty bad problem to have in traffic. Hopefully it stays fixed and I wont' have to comment back

I had this issue recently as well. For me at least it was the PVC connection on the inlet that was loose when the new inlet was installed.