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2011 WRX Power Loss - Intermittent

12K views 14 replies 5 participants last post by  yox 
#1 ·
My first major issue with my 2011 WRX since I bought it new. I only have 37,000 miles on it and I don't drive it hard at all.
I am accelerating linearly and the car loses power for 1/10 second then regains full power, then loss again....basically pulsates until I reach my cruising speed.
It happens in any gear. It happens no matter if I accelerate hard or moderately. But it doesn't happen all of the time.
The RPM's don't drop with this power loss.
My car is under a 7 year bumper to bumper warranty no deductible. The dealer will fix it, but they have to know what is wrong first....understandable!!!
Every time I bring it in to the dealer, it doesn't act up.
I was told to bring it in when it does act up, so I am waiting to be around the dealer when I notice this issue.
Any thoughts about my car's problem would be greatly appreciated.
Thank you.
 
#2 ·
I had a similar issue with a toyota dealership when my clutch was shot, they refused to find the issue until 500ish miles over the 60k warranty.

We need more info. Only after a "cold start" or does it also happen after driving for an hour? Does the gas station you use make a difference? What RPM range does it happen in? Are you going WOT? Any mods?

You have a DBW throttle which means the gas pedal is an input sensor that reads TPS and tells the throttle body how much to open. If that pedal sensor gets wet or damaged it could cause similar issues. That's just the first thing that comes to mind.

Again more info is needed to help diag. I worked for Toytoa, went to automotive school (4.0GPA in all labs), and do almost all my own work on my 02 wrx.
 
#3 ·
Wow, that's an interesting puzzle!

Does it happen when you accelerate without going into boost? (light throttle)

This would eliminate anything boost control related (if it does it without going into boost). In which case it would point toward sensors or dirty fuel system components or something in that direction.

If it only happens when you go into boost (even light boost), I'd be thinking boost leak which is very common on our gen. Besides that issues with boost control could cause this type of behavior.

Any CELs in your dash?

When you say loses power, is it more like fluctuating power, like it accelerates unevenly... or like straight brickwall loses power (complete power cut with jerking / hesitation).
 
#4 ·
Hey there.....sorry for the delay in answering your questions.
A couple of things....
The only mod I have is a short throw shifter....installed when brand new by the dealer.
The slight loss of power happens both during boost and also with slight acceleration. The dealer said he checked any leaking from the turbo...and there were none.
It is not complete loss of power....just a jerking feeling of losing some power.
This issue seemed to start happening this past winter. Here is the scenario...I put the car into reverse and happen to be on a patch of solid ice and the traction control prevented my wheels from spinning. I certainly didn't over rev the car, but then I felt this power issue right after that happened. What could have happened? Any thoughts would be great appreciated. I really enjoy my car and I want to keep it a long time, but this problem really keeps me from enjoying right now.
Thank you for your time.
 
#5 ·
That's still not enough info. VSC/TCS will not cause things like this unless a sensor is damaged, and most of those sensors are inside the car. So back to what was asked before, how long after you start the car does this happen? Did you get fuel shortly before? What scheduled maintenance has you skipped? When you say partial throttle, do you mean 1/4 or 3/4 or everything between?

Are you using 91oct or 93oct? Fuel can do things like this, especially if there's water in the tank. Do you use fuel additives? I kinda have a hard time believing you have a turbo car and don't have fun with it (hence your "I don't drive it hard at all").

Know anyone with a 2011+ wrx and an APv3/Tactrix cable you can use to datalog?
 
#6 ·
Starts to have the power loss within 1 minute of driving. The power loss is intermittent. Not every acceleration run do I feel the issue. Seems to be occurring more often now.
The tank was 1/2 full since it happened in the middle of the week and I get gas on the weekend.
Octane rating of the gas I use is 93.
I change the oil (always synthetic) every 6 months....usually having driven 2-3000 miles. That's pretty much all of the maintenance I have done.
Never used a fuel additive.
When I say, "partial throttle" I mean just slightly accelerating...maybe 1/8-1/4 throttle.
I do have fun with my car, just don't run it hard all the time.
Do you think it has anything to do with the clutch slipping?
Thanks again for taking the time to help me. I really appreciate it.
 
#7 ·
I can tell you that it has nothing to do with your clutch. I also think your clutch slips due to driving style over any other reason :).

Does the car have a noticeably louder turbo spool type sounds?

I once again go back to something like a boost leak or some other leak before the turbo (or even a vacuum leak farther down in the manifold somewhere). When I have a boost leak, it definitely makes the car not accelerate smooth as the air fuel ratio gets confused due to lost air. The problem is that the air usually isn't lost all the time, but only under specific conditions and so it goes back and forth on power sometimes. But one specific sign is you can usually hear a boost leak from inside the car.

It would be very beneficial to connect to an access port or tactrix cable to log the data so we could see what your car is doing underneath. I understand this is an expensive and/or technically complicated task for a lot of people (the logging part).
 
#9 ·
This is interesting.

I have 2016 WRX 6MT bone stock except for short throw shift, and I have a little more than 15k miles on it.

I have experienced intermittent power loss (although i wouldn't describe as a loss, more like leak of power) during mild acceleration.

It does not occur frequently: over the 15k miles maybe I've experienced it 2 or 3 times.

I know nothing about cars, but I did notice that this slight loss of power occur in higher gears (5th accelerating to 6th or on 6th accelerating). I wanted to look at the turbo gauge when it happens but it is very transient so it's hard to do that.

Assuming that everything in my car is working correctly (low miles and I don't abuse my car), I thought it might be a sudden drop in air pressure in front of the car and turbo responding to it (although I am not sure how likely this is). Sorta like how airplanes go through a vacuum while flying, causing the plane to dive a little...

If anyone can figure this out that'd be great...I just hope it's nothing with the car...
 
#10 ·
May I suggest starting a new post for this issue? This way we can stay on topic of the problem the op of this thread has and also help you out in yours.

Also, your car is quite different from the 2011 and has a totally different engine with different types of sensors on it too.
 
#11 ·
The problem seems to be occurring more often. I will bring it back to the dealer soon and let them drive it for a while. It's still under the extended warranty with a zero deductible, so I'll try to let Subaru fix it for free.
I truly don't hear any difference with the turbo than before this problem. If the problem was a turbo boost leak, wouldn't the RPM's fluctuate? My tachometer never bounces when I get this slight loss of power.
You also mentioned a "local tuner." What type of shop is this?
Thanks again for helping me with your posts. I do appreciate it.
 
#12 ·
RPMs only fluctuate if the clutch is slipping.

Google "Subaru performance shops near me", browse the forums for a reputable tuner, and talk to them to decide who you want to trust with your car. WARNING, this will void your warranty.

And yes, with an aftermarket/performance turbo inlet you need a tune. You're allowing airflow to move easier and bring more air in than stock.

Try to find someone with a stock inlet and test it out before going to the dealer if you can. Otherwise take it in, leave overnight and have them try it a few time a day for a couple days. Just don't get your hopes up.
 
#13 ·
The power fluctuates during a boost leak (you can feel the boost being uneven) but that does not mean your RPM jumps around. Also you can hear the turbo sound change and it can be very subtle or very noticeable depending on where the boost leak is and how big it is.... for example, if you just have a small hose off somewhere then you're losing a pretty constant amount of power, if you have a hose loose, that only is able to let out (but a lot of it) after you reach a certain boost level, you will feel a slight dip in power as you build up boost pressure and from there on you will hear all sorts of little noises as the ECU tries to get the boost under control. Or sometimes you will hear a high pitched squeaky sound (like taking a balloon and squeezing the neck as you let sound out).

I'll say it again, all sorts of things can happen depending on the type of boost leak. I've had many different types of boost leaks, especially when I was pushing above 20psi on a VF39 with stock connectors and it would pop them off until I replaced all connectors/clamps to much beefier ones).
 
#14 ·
All of you have been very kind to give me possible solutions. Thank you.
With those suggestions, I'll drop it off at the dealer again (for free) and see what they can do. Letting them drive it for a while hopefully helps.
I'll post something when I get more information about my car.
Thanks again.
 
#15 ·
After 6 months, my WRX is finally fixed.
I brought it to my dealer where I purchased the car. They kept it for a week, and reflashed the computer. They gave it back to me and nothing was fixed. They indicated what rpm's I should be running the car. That kind of annoyed me since I have been driving that car for more than 5 years, and I know its shifting points. I also have been driving stick shift for 25 years.
Then they kept it for 3....yes 3 weeks in June. They installed a valve AY air bypass.....and gave it back to me.....again, nothing was fixed. The loss of power was so obvious. Did they think when giving it back to me that I would just accept the issue????!!!!
I gave up on them. I brought it to Grand Subaru in Bensenville, IL and they kept it for 5 days and FIXED it.
The culprit.... erroneous output from the MAF Sensor. It was fixed under warranty. Glad I purchased the 7 year warranty.
While they were working on it, they noticed that the AC condensor was leaking....replaced that under warranty as well. I'm so happy with Grand Subaru.
It's good to have my WRX running like new.
 
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