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The Stumble/Stutter Thread


eightballrj

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2008 Subaru Legacy GT lim

Intermintantly has rough shutter at full open throttle

 

All stock other then turbo has Subaru OE VF52 done 3000 miles ago

No tune at all

 

Used to have misfire codes for cylinders 1,3,4 intermintantly

 

Checked gas for water content, checked sensors couldn't find anything. Loose or disconnected, did real time diagnostic with snap-on scanner all sensors working in proper voltages and peramiters

 

Maitnance/repairs

Spark plugs replaced 3000 miles ago

Timing kit done 1000 miles ago

Maff cleaned

New turbo oil feed lines

New transmission replaced bad one

Used royal purple max automizer fuel injector cleaner helped smooth out idle

Does not stutter or surge under full open throttle anymore been about 50 miles since

 

Still has shutter for a second intermintantly right before car comes to a dead stop still starts and shutters or shuts off after firing up then do a few key Cycles And fires up and runs just fine

Edited by 08legacygtturbo
Missed some info
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I don't actually want to be here, but... my vehicle qualifies. This is the first time I have posted about this despite doing as much research as possible.

 

I have owned a 2005 LGT 5MT for about a year now. Purchased in Florida and transplanted up into Ohio/Michigan area. I didn't notice the stutter/stumble when I first got it, no CEL either. Over time it has progressed to a point that I was/am sure that there was a true intermittent misfire occurring. The owner stated all maintenance was done at a Subaru dealer, and there was papers to prove that. Stage 2 parts and tuned, supposedly. With 15 psi max. It is my first turbo car so it was a fair amount of adjustment.

 

The stutter was getting worse and I was fed up. Purchased AP v3, installed over the weekend. It discovers it has a Cobb tune on it already. I install the Stage 1 tune that similarly runs 15 psi; I'm trying to be cautious, right? I'm aware of the ringland problems and fear the worst. So lets get into it, I guess..

 

TYPE OF STUTTER/STUMBLE

Steady throttle/Increasing throttle/Both: Steady throttle, very minor increase

 

MODS

Intake: Stock

Exhaust: Stock

Other: Aftermarket header, catless up pipe, down pipe

Fuel: 91

Turbo: Stock?

Engine Management: AP

Tuner and revision of tune(if you don't mind): Stage 1 Cobb

 

MAINTENANCE

Sensors changed: None

Plugs changed: None (but soon to come)

Coil Packs changed: None

Other: Cleaned MAF, it was super dirty, nearly impossible to get clean, checked yesterday, dirty once again

 

OTHER SYMPTOMS

Check Engine Light: Yes, P0303

Etc: and EGT?

 

RESULTS

What has and hasn't worked for you: MAF cleaning

If something worked, how long has it been working for: N/A

 

To continue (I know this is long), since installing the new Stage 1 tune and clearing out the previous map, the CEL now comes on with a cylinder 3 misfire after driving under certain conditions (see next paragraph). Not really surprised. Whenever I felt the stutter/stumble I thought "that feels like a misfire, but no CEL.. what the hell." Now I have somewhere to look and datalogging capabilities to assist.

 

However, I am new to this datalogging thing, but I want to learn what is necessary to be successful with it. I have found cylinder 3 has recurring knock and roughness. Significant under 0.55 load and around 2000-2500 rpm. Not to say it doesn't occur under similar load around 3200, but it is less severe and less frequent in occurrence. And at times at idle under hot conditions.

 

So, I will be compression testing (oh god, fingers crossed) and changing plugs, checking results. If not successful, swapping coils. If not successful, swapping injectors..

Edited by LegaLude
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However, I am new to this datalogging thing, but I want to learn what is necessary to be successful with it. I have found cylinder 3 has recurring knock and roughness. Significant under 0.55 load and around 2000-2500 rpm. Not to say it doesn't occur under similar load around 3200, but it is less severe and less frequent in occurrence. And at times at idle under hot conditions.

 

So, I will be compression testing (oh god, fingers crossed) and changing plugs, checking results. If not successful, swapping coils. If not successful, swapping injectors..

 

The first post in my misfire thread is a long read but it may give you ideas on things to try.

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The first post in my misfire thread is a long read but it may give you ideas on things to try.

 

I have seen this thread and read it, but this was before I had a better understanding of my own car's issue. I will read it more thoroughly again. Thank you!

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If it helps, contact my Tuner www.tuningalliance.com he's a great Tuner. He can answer all your questions and send you a better map if you need.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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  • 2 months later...

TYPE OF STUTTER/STUMBLE

Steady throttle/Increasing throttle/Both:

 

MODS

Intake:Cobb SF

Exhaust:Catless DP/ Straight pipe, no mufflers.

Fuel:Stock

Turbo:stock

Engine Management:Cobb Stage II OTS

Tuner and revision of tune(if you don't mind):

 

MAINTENANCE

Sensors changed:

Plugs changed:

Coil Packs changed:Plugs just changed 15NOV2015 / 71k. Front AF / 02 sensor ordered ( rolling dice ).

 

OTHER SYMPTOMS

Check Engine Light:

Etc: No check engine light non what so ever. Misfire early in morning. Ordered o rings for upper intake manifold. only CEL i have gotten ever was a P0244. Maybe it might be a tuning issue? I dont know. I know its a touchy car right now. But she climbs hard 3-4 now that updated the cobb AP with the up to date firmware. have not checked boost levels now.

 

When engine has reached operating temperature, sporadic engine stall when coming to a stop sign or light. If you blip the throttle as per video, it wants to stall but rebounds. Other than cleaning the OCV, TPS, ordering new front 02, then replacing on a hunch a #4 coil, then #4 injector, im at a loss.

 

RESULTS

What has and hasn't worked for you:

If something worked, how long has it been working for: Ive only had the car for a week and a half / 2 weeks. Inherited someone elses troubles i guess you could say. It is what it is. it is my car now though. But Seems to be a very common problem though. I just wish it would spit out a CEL for me, then i would know what to do. Here are two videos for reference. First video is of the morning start up. It is misfiring. Orings for upper intake manifold????Maybe. Ill let you all know.

 

2nd video was just a little bit ago. Blipping throttle. You can hear and see it wanting to fall on its face but then quickly rebounding.

 

 

1/

http://i72.photobucket.com/albums/i171/Crucifix79/Mobile%20Uploads/th_20151117_063038_zpsxiz7qikw.mp4

 

2/

http://i72.photobucket.com/albums/i171/Crucifix79/Mobile%20Uploads/th_20151117_164852_zpsw4pauspp.mp4

 

Edited by RaGe

OTM.

Sorry I didn't mean to start a war which mainly forum people is all about ;).
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^ Your issue is not what others in this thread are/have been experiencing. Your issues sound a vacuum leak. Possibly a BOV lifting at idle.

 

On a side note... we have done some extensive testing on the 2015/16 STi and have come to a solution that eliminates the stumble 99.9%. It takes a mechanical change and a tuning change. Eliminate the "water hammer effect", eliminate the fluctuation in fpr reference vacuum, modify specific cells of the map, modify specific learning attributes to specific cells in the map. I say 99.9% because on pump gas you can barely feel it every once in a while. You have to be "testing" for it. No passengers have ever detected it. On e85, it is smooth as glass.

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Just put on a new BOV ( GFB ) too when i installed the perrin Top mount. Ill go back out and take it off and re-check everything.

OTM.

Sorry I didn't mean to start a war which mainly forum people is all about ;).
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  • 2 weeks later...

My friends car:

1995 Legacy AWD 5speed with hill holder. EJ22 Engine.

 

TYPE OF STUTTER/STUMBLE:

Stuttering/hesitation randomly for a few seconds while foot is on the throttle, then it's fine. Sometimes it stalls while coasting in neutral or clutch is pressed.

 

MODS: None

 

MAINTENANCE:

New spark plugs.

Inspected the Mass Air Flow Sensor visually but not electrically.

New front oxygen sensor.

New fuel pump and sump filter when the pump failed recently, new engine compartment fuel filter as a precaution, the stuttering/hesitation was there before and after the replacements.

 

No check engine lights.

 

We hooked a multimeter to the fuel pump to watch how much current it was pulling to let us know if it was shutting off, current stayed steady while hesitation occurred while driving.

 

Hooked a wire to one of the spark plug wires and ran it inside the car, when the hesitation occurred while driving we brought the wire 1mm away from a grounded part of the car and saw the arcs, meaning the coil was firing just fine during the hesitation, ignition is not the cause of the hesitation.

 

Then we hooked an oscilloscope to one of the fuel injector wires and watched the pulses while driving and sure enough we saw the pulses cut down to almost non-existent when the hesitation occurred.

 

Something is telling the engine computer to kill fuel delivery to a very small amount while foot is still heavy on the throttle.

 

Throttle position sensor?

Mass air flow sensor?

Coolant sensor?

Loose wire somewhere?

 

I don't see a knock sensor or MAP sensor anywhere on the engine or in the shop manual.

 

Swapped the front oxygen sensor with the rear one and it didn't fix the hesitation. Then he bought a new oxygen sensor for the front and it still didn't fix the problem.

Edited by White95legacy
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  • 3 weeks later...

TYPE OF STUTTER/STUMBLE

Steady throttle/Increasing throttle/Both:

 

MODS

Intake:Stock W BLITZ filter

Exhaust:Stock

Fuel:Stock

Turbo:stock less than 30K

Engine Management: stock

Tuner and revision of tune(if you don't mind):

 

MAINTENANCE

Sensors changed:

Plugs changed: changed spark plugs and VGC's about 1k ago

 

 

OTHER SYMPTOMS:

Only had this car for a few months so I'm still getting a feel for it. The best fuel I can get here is 91. I recieved the car with what I think was a few gallons of 87 and the surge in acceleration was terrible. After getting it filled with only 91 the surge greatly smoothed out but at times I still feel a very light surge/stutter around 75%-WOT. It seems to increase progressively in colder temperatures (30-20° here recently) and occasionally occurs in normal driving at these temps. Assumed ECU pulling timing in response to knock. (normal driving for me has been described by passengers as rather aggressive though so…). Thoughts?

 

These symptoms have been consistent with one acception, I work on cars for a living and this situation quite confused me, here we go:

Stopped at a gas station abou a mile away from my shop for some snacks on lunch. Turn of car go in come back try to start car, car starts to turn over and quits... Ok try again, starts to turn over stops... Ok make sure my lights (HID's) are off and any other electrical draws are off. Turn key, car fires up as if nothing even happened just like normal, but something felt different, so what does any responsible rational car owner do? Light it up. The weird part was that the little stutter it has on its way to redline was completely gone, and it pulled harder than I'd ever felt it before. Wired right or am I just missing something obvious. Al startups since have been normal.

Edited by BAD-WOLF
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These symptoms have been consistent with one acception, I work on cars for a living and this situation quite confused me, here we go:

Stopped at a gas station abou a mile away from my shop for some snacks on lunch. Turn of car go in come back try to start car, car starts to turn over and quits... Ok try again, starts to turn over stops... Ok make sure my lights (HID's) are off and any other electrical draws are off. Turn key, car fires up as if nothing even happened just like normal, but something felt different, so what does any responsible rational car owner do? Light it up. The weird part was that the little stutter it has on its way to redline was completely gone, and it pulled harder than I'd ever felt it before. Wired right or am I just missing something obvious. Al startups since have been normal.

 

This sounds like the ECU reset and forgot any of its long term trims. Whenever mine resets (happens after a battery disconnect mostly) it idles funny for a few minutes. Maybe your ECU had been pulling timing due to the 87 the previous owner used, and now it's not?

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This sounds like the ECU reset and forgot any of its long term trims. Whenever mine resets (happens after a battery disconnect mostly) it idles funny for a few minutes. Maybe your ECU had been pulling timing due to the 87 the previous owner used, and now it's not?

 

Yes that was my initial assumption, good to see I'm not the only one who thinks so. I told that to one of the senior mechanics at my shop and he just laughed at me, I didn't think it seemed too far fetched but he's one of those Subaruphobes so I don't expect him to know much about my car.

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One thing to check....

 

I just went out and found the throttle body hose is wrapped up and around. I found this by blowing on the bpv hose ( small hose ) and nothing but air was heard.

 

I still have to peel the upper intake manifold off and install new gaskets to totally seal it but you might want to run your fingers along here and see if it flipped, or take that small hose off of your blow off valve and blow in it and if you are able to fully blow in it with no resistance, then you need to trace it down.

 

car has 71K on it too btw.

1950234928_crawford002.jpg.2d51689d4da605bdd0f4c713dc2dedcc.jpg

OTM.

Sorry I didn't mean to start a war which mainly forum people is all about ;).
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  • 3 weeks later...

Ok so since my last post car has been putting out some hazy smoke time to time took off my tmic to see that even after the new turbo I am still getting quite a bit of kiln going through my engine but it has either coolant or moisture mixing with it and it pools up In the hose right at the throttle body and that's what it causing my engine to shutter when braiding if there is enough built up it sloshes over the throttle body last oil change I went 3,400 miles and had lost 2 and one a half quarts of oil within that time added the oil as needed coolant level perfect has never been changed since I got the car in 2013 so my question is seems how I have a new turbo that may or may not have a leaking seal if it does not leak at a seal what are other places that oil could be coming from that can go into the intake is there and crank case pipes that could have oil pushed or sucked up into the intake like a pvc Valve or anything I don't have a ton of knowledge or experience with boxer engines and their systems any help to what might be the culprit would be greatly apriciated

 

If I can figure out how to post pics I'll add some of what it looks like inside the turbo and hose for throttle body

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Ok so since my last post car has been putting out some hazy smoke time to time took off my tmic to see that even after the new turbo I am still getting quite a bit of kiln going through my engine but it has either coolant or moisture mixing with it and it pools up In the hose right at the throttle body and that's what it causing my engine to shutter when braiding if there is enough built up it sloshes over the throttle body last oil change I went 3,400 miles and had lost 2 and one a half quarts of oil within that time added the oil as needed coolant level perfect has never been changed since I got the car in 2013 so my question is seems how I have a new turbo that may or may not have a leaking seal if it does not leak at a seal what are other places that oil could be coming from that can go into the intake is there and crank case pipes that could have oil pushed or sucked up into the intake like a pvc Valve or anything I don't have a ton of knowledge or experience with boxer engines and their systems any help to what might be the culprit would be greatly apriciated

 

If I can figure out how to post pics I'll add some of what it looks like inside the turbo and hose for throttle body

 

Ok, I'll bite. I'll help make your question(s) easier to understand. You won't get any answers here though, you'll need to post in the correct section. Don't take offense, I'm just trying to be helpful. I recommend creating a new thread in the Turbo Powertrains section. That would be the perfect place to discuss your unique problem, and a really great place to show us pictures of exactly what you're talking about.

 

Since I last posted, my car has occasionally been putting out some hazy smoke.

 

I took off my TMIC, and even after getting a new turbo it looks like there is still quite a bit of fluid going through my engine. It looks like it's either coolant or moisture. It pools up in the hose right at the throttle body. When enough liquid build up sometimes it sloshes over the throttle body during braking.

 

My last oil change interval was 3,400 miles, and it had lost 2.5 quarts of oil during that time. I added the oil as needed, and the coolant level has been perfect (it's stayed full since I got the car in 2013).

 

Here's my question: Is there a leaking seal in my new turbo? If there isn't a seal that could be leaking, what are some other places that oil could be coming from to go into the intake? Are there crank case pipes that could be letting oil get pushed or sucked into the intake? Like a PCV valve?

I don't have a ton of knowledge or experience with boxer engines and their systems. Any help figuring this out would be greatly appreciated!

 

If I can figure out how to post pics I'll add some of the turbo and throttle body hose.

Edited by StkmltS
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TYPE OF STUTTER/STUMBLE

Steady throttle/Increasing throttle/Both:

 

MODS

Intake:Stock W BLITZ filter

Exhaust:Stock

Fuel:Stock

Turbo:stock less than 30K

Engine Management: stock

Tuner and revision of tune(if you don't mind):

 

MAINTENANCE

Sensors changed:

Plugs changed: changed spark plugs and VGC's about 1k ago

 

 

OTHER SYMPTOMS:

Only had this car for a few months so I'm still getting a feel for it. The best fuel I can get here is 91. I recieved the car with what I think was a few gallons of 87 and the surge in acceleration was terrible. After getting it filled with only 91 the surge greatly smoothed out but at times I still feel a very light surge/stutter around 75%-WOT. It seems to increase progressively in colder temperatures (30-20° here recently) and occasionally occurs in normal driving at these temps. Assumed ECU pulling timing in response to knock. (normal driving for me has been described by passengers as rather aggressive though so…). Thoughts?

 

These symptoms have been consistent with one acception, I work on cars for a living and this situation quite confused me, here we go:

Stopped at a gas station abou a mile away from my shop for some snacks on lunch. Turn of car go in come back try to start car, car starts to turn over and quits... Ok try again, starts to turn over stops... Ok make sure my lights (HID's) are off and any other electrical draws are off. Turn key, car fires up as if nothing even happened just like normal, but something felt different, so what does any responsible rational car owner do? Light it up. The weird part was that the little stutter it has on its way to redline was completely gone, and it pulled harder than I'd ever felt it before. Wired right or am I just missing something obvious. Al startups since have been normal.

 

 

I know its been a few weeks, How is the car running ?

 

You really should have the tuned to clean up the stock timing issues.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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  • 2 weeks later...
TYPE OF STUTTER/STUMBLE

Steady throttle: Steady slight stumble at idle. Car has stalled in slow traffic and one time in parking lot with car in drive and foot on the gas(simulated traffic).

 

MODS

Exhaust: SPT cans and CNT Highflow Cat DP

Fuel: 93

Turbo: VF52

Tuner and revision of tune(if you don't mind): Road Tune

 

MAINTENANCE

Sensors changed: Rear O2

Plugs changed: OEM

 

OTHER SYMPTOMS

Check Engine Light: Rear O2 sensor (P0420)

 

RESULTS

What has or hasn't worked for you:

Carb cleaner tested vacuum lines/Intake Mani/Injectors, Cleaned MAF sensor, Changed air filter, SeaFoamed fuel system

Replacing the O2 sensor removed P0420

 

Timed the car to get a better sense of when things were happening. The timeframe below happens each time(0:00 to 4:40).

 

Started timer

0:30 Almost stalled twice(had batt unplugged)

3:56 Almost stalled/big stumble

4:30 Started hunting for idle (possibly from entering closed loop)

4:40 Slight stumbles are constant/no code/rpms remain at a constant 800

18:00 Carb cleaner tested vac lines, intake manifold, and injectors(no _______change in rpm

25:00 Shut the car off

 

Drove the car for well over 30 minutes. Gave her the beans and everything. Power is all there still. Stumble is felt during low idle, i.e. sitting in parking lot or slow traffic. Low on funds right now so can't really get it diagnosed. Possible front O2? Gunked up throttle? I can at least afford a nother bottle of Seafoam for the intake. Any other ideas for an empty wallet guy?

 

Oil light started coming on. Took it in and found that the oil pump was on it's last legs. Also had the gas pedal replaced. Apparently the sensor at the pedal was dying. No problems since replacement. Been about 500 miles.

VF-52 and all associated bits tuned by Tuning Alliance.

:cool:

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  • 1 month later...
Oil light started coming on. Took it in and found that the oil pump was on it's last legs. Also had the gas pedal replaced. Apparently the sensor at the pedal was dying. No problems since replacement. Been about 500 miles.

 

UPDATE: Problem came back with force. I was driving apx 50mph and the car lost power and throttle response for a few seconds. CEL came on and car regained throttle response. P0340 for the camshaft circuit. Took it in and they tested the circuit and found that one of the signal lines was showing something like 10Mohms of resistance. This is probably what was causing my issues from the get go, but it never threw the code. Having them test the harnesses to see if it is only the one wire. Hopefully it doesn't decrease the weight of my wallet too much.

VF-52 and all associated bits tuned by Tuning Alliance.

:cool:

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  • 2 weeks later...

Stock injectors should be fine on a stock VF46. I imagine you'll have trouble hitting 22psi with a stock boost controller, you might want to upgrade to an EBCS. For reference, I have a JmP Custom VF46, and my tune targets around 19psi with a GS EBCS, using max wastegate duties of around 70-75% on the stock wastegate spring.

 

I assume you're planning on getting an actual tune done, and not using a Cobb OTS tune? You should not be running an intake without getting a proper tune, and until you do, I'd stay out of boost. You can likely get an e-tune done from a decent tuner without a wideband, but getting a wideband will speed up and improve the process, for sure.

 

Plenty of e-tuners on the forum here. I'll go ahead and jump in before Max Capacity does (:lol:) and recommend Tuning Alliance for your tuning needs.

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