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undulating power going up hills/ stepping on it

4K views 7 replies 4 participants last post by  GSMNZ 
#1 ·
Hi all,
Im new here, and fairly new to the subi world.
My 2006 Wrx has been losing power (not to the point of stopping) and giving me some undulating power going up hills and when i get on it... so really only ever under load.
Ive had this happen in the summer in the middle of nowhere and it seemed to work itself out within 600 miles.
I figured that was some bad gas or something and it went through the system.
It just happened again yesterday, i caught it and filled up again and threw a half a can of seafoam in there, perhaps a little difference over the next 2 passes and 90 miles to home base.. but you could still feel some hesitation.
My question is.. are these engines very picky about their gas? ( i only run 91 because its cheap for the now)
or is there something else going on here?
ive never had bad gas experiences here before but then again i drove a tank of a surburban.
No codes are flashing, and my accessport isnt showing anything wrong (then again what should i look for?)
Keep in mind i know some mechanics... but am not at all at a professional level (obviously because i wouldn't be asking for help)
Thank you!
 
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#2 ·
Hey Hannah (I hope that's your name, I'm basing on your username)

Welcome to the forums!

No, this is not a normal behavior, even if running lower grade gas (which I would recommend not doing because it can leave your motor more prone to knocking (ie detination) which over time can kill the motor). In particular if you have any sort of non-stock tune or mods.

(Edited out because I didn't read your post all the way).

Do you have an Access Port or Tactrix to monitor your ECU? It would be benefitial to be able to look at what the computer is doing to cause this.

Is the power all of a sudden cutting out after being there (sporadically) or is the power not coming in at all as it should?

I would go ahead and check to make sure the wastegate flapper and actuator are not sticking. This happened to me a few times which causes the turbo to not spool (or worse, gets stuck closed causing overboost).

Welcome again, post pix of your car!
 
#3 ·
What modifications have been done to your car? Anything that would have to do with Air in, boost, fuel, exhaust etc. (not cosmetic, tires, transmission or suspension related)

I would log an event if possible un upload here. Your going to want to make sure you are logging DAM (dynamic Advance Multiplier), AFR (Air/Fuel Ratio) sensor 1 and 2, TPS (Throttle Position sensor), Boost, and Target Boost.

I would do a log going up hill and one on a straight away.

I wouldn't put in any more sea foam. Run 93 if possible.

Could be a boost leak or bad plugs.
 
#4 ·
Hey RUSO,
I do have an accessport v2. The power is pretty sporadic. Noticed it quite a bit this morning on my way to work. I would be at a constant 25 mph then get a quick jolt (similar to your heart skipping one or two beats) then goes back to normal.
I've noticed it more at 2.5 to 3 rpm which if I'm correct is where the turbo is spooling. @GSMNZ I don't think there is anything besides stock under the hood. I have a stage one tune but nothing to my knowledge has been upgraded. I will try to log that today but lord knows it won't do it when I need it to hahaha

Sent from my SM-G920V using Tapatalk
 
#5 ·
Take a look at the turbo wastegate actuator (when the car is cold so you don't burn yourself). Try to move it by hand (pulling the rod left (toward the firewall/downpipe side) will allow it to open the wastegate.

See if it's sticky, also if it's rubbing on the hole. If it creaks or makes noises, it's ok, UNLESS it moves sporadically.

I am not sure if this has anything to do with it though but it's probably the simplest check you can do.
 
#6 ·
Sounds like you're running out of fuel/overboosting and the ecu is compensating by cutting ignition to attempt to prevent detonation. My bugeye does this and I have crap injectors combined with a full exhaust, so now she sits. Also FYI winter blend fuels have more additive than normal so running 91 in the summer might not be as bad, but always use 93 even if you are tuned on 91 (protune using 91, then running 93 after that). OTS maps should be use for nothing more than a base map or short term use.

And I second the question about your intake/exhaust setup as any flow changes (besides a cat-back) will cause fueling issues unless you get a protune. You're running the ej255 so I'd make one of 2 choices: Stop driving your car until you get it checked and fixed, or start using 93 combined with light driving until you figured out the issue(s). All turbo 2.5 EJs are known for pistons crapping out (even on OEM tunes) from stuff like bad gas, poor tuning, mods w/out tuning, and more. But hey if you want to risk needing a new engine keep driving in boost.

Get some logs and post them up. Btw if you can hear the rumble more than just a bit you might have an aftermarket DP
 
#7 ·
Robotuner-
They do not sell 93 up where I live... the highest I can get at the only costco for 200 miles is 92.
I haven't been able to log anything these past few days, we just got a crap ton of snow.

This is starting to sound like something above my level of expertise/pay grade. I'll see if I can get a shop around here.

Sent from my SM-G920V using Tapatalk
 
#8 ·
If you can only get 91 that's ok. What tune are running on your Cobb AP? Stage 1? Still stock?

Cobb has some videos on Youtube on their AP if you want to learn more. It will help you out tons if your new to it.
 
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