Wrx sputtering hesitation when boosting.

[Gamaraye]

Deleted

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[drifter001]

I hate to bring back an old thread, but my 05 wrx just did similar....did a quick pull under wot coming onto the freeway and was fine...about 20 mins later, did a pull after an interchange and sputtered from about 4000=4500 rpm then pulled through and boosted fine. I have been having an issue with my battery terminal cables. MAF sensor is new and no check engine light on


*update
Ive reset the ecu and for the time being, it seems like the issue has resolved itself. i have found out that I'm overdue for new spark plugs so gonna replace those soon as well

[romeoridgee]

has the problem been solved? m0nkey

[prohispano]

Im having something related, had already 4 months with new NGK 1 Step colder Iridium plugs, that solve this sputtering wot, but now at 15 psi vf39, it again sputtering at 5k Rpm and its very Hard hessitation, all the car shakes and rpm bounce at those rpm, could be coil or dirty MAF?

[prohispano]

Please some one help me

[05SilverDadWagon]

My car was doing this, ended up being a boost leak. My throttle body coupler was bad.

[prohispano]

How can i check if i have boost leak there?

[danger1138]

^^Remove coupler , inspect it for any tears. Especially the part where the hose clamps sit.

[prohispano]

Okk i will check for leaks, i will lower my boost from 16psi to 12psi, and see if u have bucking.

[prohispano]

Ok theres no more hesitation at 11psi, my wrx its an 02 so im using turbo XS manual boost controller , it can be coils? or dirty maf or dirty or bad gapped sparks?
Today ill be cleaning MAF, i will report later the results.!

[prohispano]

Sorry but ive to update my last post for results! well now i clean my maf everything its okay, boosting 16 psi solid as a rock till redline! Thanks for the people who read this

[thesirmario]

Yet another possible cause of this: i had the same problem, my cause was the stock bpv wasn't able to vent enough air fast enough. My solution: gfb Mach 2. I tweakerfied with the adjustment screw when it was all the way down then slowly (1 turn at each time) decreased the spring pressure while listening for the fluttering sound after I let off the gas. So, if you have an upgraded turbo, and that wot-> seems like car is unable to handle the air that's coming thru your engine but rpms increase, check on that stock bpv, it might not be venting enough air and it's causing compressor surging activity

[IITurboMikeII]

I was a little hesitant to necro this thread when I found it, but then saw it has been necroed a couple of times.

I have an 03 WRX with similar issues. Off boost performance is fine, Once boost comes on, its fine to about 10psi, then has seems to lose power. I can hear the turbo, but the farther I press the pedal, the more it seems to slow down. I took a log with my Accessport, but I don't exactly know what I'm looking for. Anybody help me out?

THe whole log Here.

About my car, 03 WRX, SPT intake, VF39, STI TMIC (from the same donor car as the turbo), and the "blue" STI injectors, 565cc if I remember right...

EDIT: may have to open the pic in a new tab, its not showing on my end.

[JDMJEDI]

I experienced the same problem for a while it was a combination of things mainly my intake to throttle body coupling replaced it with a new oem dealer one and also changed my knock sensor and bcs

[cdcee]

Bump. Just installed a new AEM 320lph pump. First drive was fine
2nd drive today wasn't. Felt much hesitation when getting into boost. Any idea what's going on?

[monkeyposeur]

I always tell people to check their grounds and battery terminal connections. The battery terminal connections can get loose and will vibrate causing symptoms similar to fuel cut.

[kannamoar]

Hey there, 05 WRX here, same issues: Stuttering/hesitation on acceleration, only under load, especially up long inclines. Keeps throwing a p0301 CEL (cylinder 1 misfire). So far I have:

... cleaned the MAF sensor (it was visibly dirty)
... changed spark plugs
... put in a new battery (possibly unrelated, but was failing most tests)

Over the next week I will be checking grounds and looking for boost leaks. I'll try my best to update this post with what things did and did not work for me.

** EDIT 1 **

So today I was just doing some more visual inspection when I found a seemingly gnarly problem...
First off, I'm barely a month into owning a Subaru, and even then, I'm admittedly no mechanic. This car is an entirely foreign beast to me...
Anyways...

So I'm doing my best to trace the flow of air and finally make it to what I'm pretty sure is the 'turbo inlet hose'. It looks dirty and kind of lose. I think 'maybe I'll just try to get another half a turn on this hose clamp'. So I reach an extended 10mm socket down there, and the whole clamp spins around the hose! This thing wasn't even finger tight..

a little background info that may help...
So the kid I bought this car from recently had some relatively serious work done to it. He had a new clutch put in, new head gasket, new timing belt, new radiator, new plugs, and all necessary gaskets for having the engine taken apart that far. He had this work done at a dealership, and my best guess is they put it all back together either hurriedly, or just wrong, or both..

Back to the story..
So I got the clamp aligned and tightened down, but now the hose seems warped. I'm obviously going to replace it when I can, but I'm wondering if this would have caused the symptoms mentioned at the top of my post? I did a couple test drives around the block, and the pulls were a ton smoother. Still seems a bit luggish in low gears at low RPM's, but the turbo spools and stays spooled, which was not happening before.

I had already found a couple other places where hoses should have been clamped, but were not. Eventually I'd like to go over every single clamp on every hose, because this makes me nervous that they forgot others too. Should I take it back to that dealership (have receipts) and make them do a full inspection on the hoses? My gut says to stay away from that dealership and take it somewhere else, anywhere else really..

Anyways, thanks in advance for any advice. I'm excited to have joined this family of Subi owners and look forward to being more active in the community as I learn about these wondrous beasts.

Pictures AFTER tightening the clamp:

http://i.imgur.com/7IG7WZC.jpg

http://i.imgur.com/wIUqxF0.jpg

[Shiftace420]

The clamp will cut through those inlet tubes no problem. IF it was not ruined already it is now. They are crap from the factory and will not last long.

Get a quality aftermarket inlet tube. Your MAF readings lower because of a leaking inlet causing a lean condition. It WILL BLOW UP your motor if you do not fix it. Stay out of boost until you get a new one. Really.

It is very important there are no leaks on a Subaru. Smoke test and or boost leak test it to be sure. Visual inspection is not enough.

[kannamoar]

So I took the car in to a local Subaru specialist shop for a compression and leak down test. They had the smoker hooked up within about 5 minutes, and smoke was pouring out of the turbo inlet hose.

I figured I would just pay the shop to do the turbo inlet, as I've watched videos and read threads about what a major, major PITA it is. So they ran comp tests and every cylinder came out to 120 (this was like receiving a phone call about test results from the hospital..). This was great news to know that the engine hadn't been significantly damaged.

At this point I should thank Shiftace420 for the advice on staying out of turbo, and basically driving like an 80 year old. It wasn't any fun, but I managed to get to and back from work safely, without causing any significant damage.

The shop also mentioned that while it isn't necessary to take off the intake manifold, that if I wanted they could do so and do the TGV deletes, while making the turbo inlet install easier. I figured what the hell. This baby is bone stock, and I'm not planning on going crazy with it either, so the deletes may not have been worth it, we'll see.

Anyway, car should be ready by the weekend and I'll (very cautiously) take her for a few spins and report back.

To those here with hesitation or sputtering problems, be sure to check the turbo inlet hose, especially if its oem like Shiftace420 mentioned. I know I didn't help with my tightening the clamp so much, but either way it was toast. Also, get right on it with a smoke test, I wish I'd done that earlier, just didn't feel like building one.

[envygreenlantern]

Lazarus here.... I was having the same problem very mildy. After getting my up pipe done the problem was much more pronounced... my Y pipe was not seated correctly on the turbo...I fixed the issue. A week later I noticed my y pipe was also cracked. After a little duct tape everything was fine.

Edit, nothing is fixed, I changed the y pipe and the fuel pump so far. I'm at about 20 psi at vacuum... I'm lost

[ukranianization]

Just logged on after a four year hiatus from NASIOC and saw that I was subscribed to this thread. Not sure if this is frowned upon, but decided to bring it back from the dead in case there were others who still haven't been able to solve this problem.

Long story short, I bought my '03 WRX with the only mod being an axle-back exhaust. After some time, I ended up having hesitation issues with it. As soon as it would start hitting boost, it would hesitate and sputter and barely have any power.

After trying what I thought was everything, I ended up taking the uppipe off as a last resort and found that the cat had come loose and was just bouncing around inside there.
As a temporary fix, I used a drill and shredded the cat to pieces until it all fell apart and came out. Cleaned it all out, installed it and the problem was fixed.

Essentially, I ordered a new uppipe along with a new turboback exhaust.

[Innkeepr]

Looking for help - sorry if the thread is old but didnt want to start a new one just incase.

Backstory - 2004 WRX - complete engine rebuild at 224K - now has 13K on new build.

Car has following mods - (NOTE - opensource tune ran great for last 13K )
ALL new sensors - cam/crank/knock/maf/o2s
new Coils - running BRK7E plugs gap to 26.
Invidia catless up pipe
VF29 running 18lbs boost ( on stock tmic )
aftermarket intake
Suabru SPT short ram
TurboXS bellmouth DP - catted hi flow
Borla cat back 3 inch SS exhaust
New STI blue injectors (565?)
Walboro 255 pump
New fuel pressure regulator
IAG AOS
independent gauges ( oil temp /press. H2O, fuel pres, boost gauge AEM wideband )
Grimspeed 3 port EBC
eliminated EGT during tune

SO, that was a lot of fun for me and my son - now here is the issue.

Started getting random misfire codes, CAT threshold, and knock.

Replaced all 4 coils and plugs - no change ( gap to 28 by others recommendation )
Further inspection - cheap ass intake showed oil actually from the BPV to turbo
Time for more upgrades, the VF29 seals are shot- so here is what we changed

Blouch 16XGT turbo - new oil line per Blouch
Perrin intake
Process West TMIC with splitter

Tried to tune today with no luck. Car ran great prior to the new additions, and my Tuner who has 17 yrs experience with turbo builds - is stumped.
We called it a night to search for answers.

Car drives fine up to 3500 rpm - then spool hits and its almost like the wastegate is fluttering, dumping pressure - then spiking, just nasty, bucking, missfire (no codes) scary actually, acts like limp mode going up hills.

We wiped the tune and threw a stock map on - no change
Installed the tune for the first mods ( vf29 ) - no change
Custom maps flashed - no change.
Car only threw a MAF code in the 20 miles of tuning, then I got a KNOCK code about a mile from home.

Vacuum is siting at 19.5 - 20 at idle. So I dont think its a leak.
Data logger shows MAF voltage at 4.8

Before I pull the manifold and replace gaskets ( last resort ) - or buy ANOTHER MAF - I have also read that my ECU may be in its death throes. Any ideas before I lose my mind ?

Thank you in advance for the help
Best wishes,
"E"

[03jdmlegacy]

Originally Posted by Innkeepr

Looking for help - sorry if the thread is old but didnt want to start a new one just incase.

Backstory - 2004 WRX - complete engine rebuild at 224K - now has 13K on new build.

Car has following mods - (NOTE - opensource tune ran great for last 13K )
ALL new sensors - cam/crank/knock/maf/o2s
new Coils - running BRK7E plugs gap to 26.
Invidia catless up pipe
VF29 running 18lbs boost ( on stock tmic )
aftermarket intake
Suabru SPT short ram
TurboXS bellmouth DP - catted hi flow
Borla cat back 3 inch SS exhaust
New STI blue injectors (565?)
Walboro 255 pump
New fuel pressure regulator
IAG AOS
independent gauges ( oil temp /press. H2O, fuel pres, boost gauge AEM wideband )
Grimspeed 3 port EBC
eliminated EGT during tune

SO, that was a lot of fun for me and my son - now here is the issue.

Started getting random misfire codes, CAT threshold, and knock.

Replaced all 4 coils and plugs - no change ( gap to 28 by others recommendation )
Further inspection - cheap ass intake showed oil actually from the BPV to turbo
Time for more upgrades, the VF29 seals are shot- so here is what we changed

Blouch 16XGT turbo - new oil line per Blouch
Perrin intake
Process West TMIC with splitter

Tried to tune today with no luck. Car ran great prior to the new additions, and my Tuner who has 17 yrs experience with turbo builds - is stumped.
We called it a night to search for answers.

Car drives fine up to 3500 rpm - then spool hits and its almost like the wastegate is fluttering, dumping pressure - then spiking, just nasty, bucking, missfire (no codes) scary actually, acts like limp mode going up hills.

We wiped the tune and threw a stock map on - no change
Installed the tune for the first mods ( vf29 ) - no change
Custom maps flashed - no change.
Car only threw a MAF code in the 20 miles of tuning, then I got a KNOCK code about a mile from home.

Vacuum is siting at 19.5 - 20 at idle. So I dont think its a leak.
Data logger shows MAF voltage at 4.8

Before I pull the manifold and replace gaskets ( last resort ) - or buy ANOTHER MAF - I have also read that my ECU may be in its death throes. Any ideas before I lose my mind ?

Thank you in advance for the help
Best wishes,
"E"

Did you figure anything out? My car is doing much the same as what you've said. I just started digging into finding the problem. Engine seems to run really well with the maf unplugged, does that rule out a lot of other issues?

[Innkeepr]

03JDM

I did get things fixed - here are the 2 changes.

1. Added another ground strap to the engine.
2. Changed MAF ! - the NEW MAF box part number was correct - the part inside was not !
The part in the box was for a 04 NA impreza - not a WRX. GRRR sometimes I hate online shopping.
Got it dialed in and did some MAF scaling - adjusted duty cycle of the EBC - now runs 21lb of boost - shifting at 7K.

[subaru_gc8]

for the coils did you use oem or did you buy some aftermarket ones