m sprank Posted June 6, 2013 Share Posted June 6, 2013 From the very first post (which is referencing an 05) "Let's define stumble/stutter as any form of hesitation at part throttle at either steady throttle input or increasing throttle input." For many cars this "hesitation" can be attributed to the transition from closed loop to open loop. Link to comment Share on other sites More sharing options...
heiche Posted June 6, 2013 Share Posted June 6, 2013 So "the cause" that I asked about is the transition from closed loop to open loop? BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT Link to comment Share on other sites More sharing options...
m sprank Posted June 6, 2013 Share Posted June 6, 2013 Sometimes. For some it has never been figured out. Hence threads like this one. But usually a tune helps tremendously. Link to comment Share on other sites More sharing options...
heiche Posted June 6, 2013 Share Posted June 6, 2013 ok thanks! BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT Link to comment Share on other sites More sharing options...
Scooby2.5 Posted June 9, 2013 Share Posted June 9, 2013 (edited) TYPE OF STUTTER/STUMBLE Steady throttle/Increasing throttle/Both: MODS Intake: AVO Exhaust: Autospeed Fuel: 93 and E85 Turbo: AVO380 Engine Management: Cobb AP Tuner and revision of tune(if you don't mind): Calvin Dotson Cobb Plano Protuned MAINTENANCE Sensors changed: MAF no difference Plugs changed: 25K on plugs Coil Packs changed: OTHER SYMPTOMS Check Engine Light: NO Etc: RESULTS What has and hasn't worked for you: Nothings worked If something worked, how long has it been working for: My car is doing this as well. I noticed that if I ever so slightly push on the pedal and watch the Throttle position on the AP it actually goes down for a split second before it increases. For example at idle with no input it is sitting at say 6. As soon as I just barely press on the pedal it goes to like a 3-4 before going up and the AFR goes a bit rich and then it hunts for a second. Myself and KCwagon have the same exact issue. Once it goes rich like that as the throttle position number goes down then it is out of whack for a bit until it settles in. Both of us were tuned at Cobb Plano, but I would think this portion of the tune was not touched. Sometimes I wonder if its an issue at the throttle body or the sensor on the pedel causing this, but its weird that both of us are having the same issue. If I hold the throttle at the point when the TP number goes down a bit the car really starts idling rough and will almost die. Its like it does not like this partial throttle and who knows what the number going down does. Anyone else have this or can test it? I just went on the AP monitor section and monitored throttle position while pushing the pedal ever so slightly with my hand. Car is fixed. Swapped OCV for the AVCS today and car is running great!!! Mine was mostly a stuble stutter when first taking off. Didn't do it all the time and in the winter it was better, not perfect but better. I finally got around to getting my ATR software going with my AP and monitored some ECU parameters. Found the AVCS ALL OVER THE PLACE. I sometimes would get crazy numbers like 40 sitting still at an idle just reving up the motor a bit. The two banks were not the same at times and my idle at times was terrible. So today I put new plugs in, and the old ones looked real good. But the real change was new OCV for the AVCS. Once I put these in my car it is running great. Those dang things affected my fuel trims B and C, had some knock once and a while, some roughness cylinder in each cylinder once in a while. I found that when I had these problems (very intermittent) the AVCS was all whacked out. Edited June 10, 2013 by Scooby2.5 Link to comment Share on other sites More sharing options...
m sprank Posted June 9, 2013 Share Posted June 9, 2013 Info posted in the product description on our website Oil Control Valves http://www.infamousperformance.net/servlet/the-1136/Subaru-Legacy-GT-Oil/Detail Oil Control Valve is the term for the solenoid valves that regulate the oil pressure driving the intake cam sprockets to clock themselves relative to the camshaft. In one position the OCVs will pressurize the system to advance the cam timing, another position to retard the timing, and the final position to lock the sprocket in place. Common symptoms that may be a sign that these need to be replaced include: -a P0011 / P0021 fault code -rough idle -stumbling at low rpm -stalling Link to comment Share on other sites More sharing options...
cfaber Posted June 10, 2013 Share Posted June 10, 2013 how deep in the engine is this valve? Winning the internet Link to comment Share on other sites More sharing options...
ssbtech Posted June 10, 2013 Share Posted June 10, 2013 how deep in the engine is this valve? http://legacygt.com/forums/showpost.php?p=1943328&postcount=8 Link to comment Share on other sites More sharing options...
cfaber Posted June 10, 2013 Share Posted June 10, 2013 This might be worth a shot.. Winning the internet Link to comment Share on other sites More sharing options...
CHLAXN Posted June 10, 2013 Share Posted June 10, 2013 A couple of weeks ago, I had the traction light come on, the check engine light came on, and the cruise light started blinking all at once. I turned around and drove straight to the dealer. Back in February, when this happened, it turned out to be the Oil Control Valve. The dealer made mention that they would go ahead and replace the Oil Pressure Switch, because this always seems to go bad after having the Oil Control Valve replaced. I guess they were right and apparently they never changed the switch because they determined that this was the problem and confirmed that they had only replaced the Oil Control Valve the first time. They said the car was safe to drive and they had to order the part. After I left the dealer, I started having problems with the car acting like it was going to stall when stopped at traffic lights. I parked it and waited for the part to come in. Replace it myself in about 5 minutes (dealer wanted $200 labor). Reset the computer and still had the same problem. The next day, I tried to drive it to work and it died at a light and when slowing down to pull into a gas station just after this. Ended up that the car just needed the trottle plate cleaned of carbon residue. Seriously?!?!?! Oh, and of course they charged me $150 to do the cleaning! Anyways, the car is running great again... I hope this may help some of you other guys that are having similar issues. Good luck!!! Link to comment Share on other sites More sharing options...
Scooby2.5 Posted June 10, 2013 Share Posted June 10, 2013 Yea yours is a 2.5i. They have a valve and a pressure switch. 2005 Turbos just have the OCV Link to comment Share on other sites More sharing options...
CHLAXN Posted June 10, 2013 Share Posted June 10, 2013 Ahhh... good to know. Well, the throttle plate cleaning should still apply... right? Link to comment Share on other sites More sharing options...
Enraged Posted September 14, 2013 Share Posted September 14, 2013 (edited) Maybe you guys can help me out. My car is an 05 LGT. There is a stumble at idle and at heavy throttle. I bought the car last year, it had a burnt valve and the dealership rebuild both heads before I purchased it. I plugged in my laptop and ran Romraider to log. #2 cylinder has roughness, usually maxing out around 10. No codes are showing. Cleaned the MAF sensor awhile ago. Car is stock aside from an AEM dryflow intake filter replacement. New battery and had the alternator rebuilt 2 weeks ago. I just swapped coils between cylinder #2 and #3. Roughness stayed on cylinder #2, so I figure it's likely not the coils then. What should I do next? Replace the spark plugs? I don't know if the dealer put new ones in when they rebuilt the heads. Otherwise, is the next likely cause the injector? I can swap those between cylinders to see if it moves. Any help would be appreciated, this is frustrating. Aside from the stumble, the car runs well. Doesn't burn oil between changes, same gas mileage as it has always been. Edited September 14, 2013 by Enraged Link to comment Share on other sites More sharing options...
ssbtech Posted September 14, 2013 Share Posted September 14, 2013 Post up a log. Where are you seeing the knock count increase? Light load? Heavy load? Part or full throttle? I'm still trying to figure out why some people say the knock sum isn't something to fret about. Link to comment Share on other sites More sharing options...
Enraged Posted September 14, 2013 Share Posted September 14, 2013 I'll try to get a log this weekend. Usually it's only noticable at idle and heavy load/full throttle. I haven't driven the car hard since it started, and if I feel a misfire I back off on the throttle. Driving around town is fine. What should I log? Knock count/sum, roughness, anything else? Link to comment Share on other sites More sharing options...
ssbtech Posted September 14, 2013 Share Posted September 14, 2013 I know nothing about this but this is what I was told to log when trying to figure out what was wrong. Eventually the engine came out for new valves too! Engine speed Knock sum Throttle opening % Engine load Feedback Knock Correction Fine Learning Knock Correction IAM Ignition Total Timing Manifold relative pressure Primary Wastegate duty cycle Boost error Link to comment Share on other sites More sharing options...
adrenalinecrisis Posted November 4, 2013 Share Posted November 4, 2013 TYPE OF STUTTER/STUMBLE Steady throttle/Increasing throttle/Both: stuttering from 2-3k, nearly every throttle position MODS Intake: Cobb short ram intake Exhaust: Catless up-pipe, catted downpipe, catback Engine: EJ257 Swap w/ CP pistons; 10k on build. Fuel: stock Turbo: stock Engine Management: Cobb stage 2 map (OTS map w/intake) Tuner and revision of tune(if you don't mind): n/a MAINTENANCE Sensors changed:knock sensor (no change) Plugs changed: plugs changed; were very white from a lean condition. from leaking turbo inlet? (no change) Coil Packs changed: n/a OTHER SYMPTOMS Check Engine Light: none Etc: Found torn inlet, leaking bpv and tmic. Replaced inlet w/OEM, replaced bpv w/OEM, bulletproofed tmic which fixed the minor leak. pressure tested to 10psi with no leaks. RESULTS What has and hasn't worked for you: The torn inlet was a big problem, but stuttering still is present. Nothing has worked at this point. I am experiencing a lot of feedback knock at low throttle/low rpm which doesn't make sense. I have no knocking under WOT. I've check probably a half dozen times for something loose or bouncing around to cause the knock, but I haven't found anything. If something worked, how long has it been working for: Nothing has worked at this point. I've been suggested to replaced my upstream o2 sensor regardless of having no codes; does that seem like a good idea? please help! Link to comment Share on other sites More sharing options...
mwiener2 Posted November 19, 2013 Share Posted November 19, 2013 Filled my driveshaft hanger bushing with Windo-Weld Polyurethane. Significant improvement in surging issues and overall driveline slack. Been meaning to do this for 5 years. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
1SIKLGT Posted November 20, 2013 Share Posted November 20, 2013 TYPE OF STUTTER/STUMBLE Steady throttle/Increasing throttle/Both: stuttering from 2-3k, nearly every throttle position MODS Intake: Cobb short ram intake Exhaust: Catless up-pipe, catted downpipe, catback Engine: EJ257 Swap w/ CP pistons; 10k on build. Fuel: stock Turbo: stock Engine Management: Cobb stage 2 map (OTS map w/intake) Tuner and revision of tune(if you don't mind): n/a MAINTENANCE Sensors changed:knock sensor (no change) Plugs changed: plugs changed; were very white from a lean condition. from leaking turbo inlet? (no change) Coil Packs changed: n/a OTHER SYMPTOMS Check Engine Light: none Etc: Found torn inlet, leaking bpv and tmic. Replaced inlet w/OEM, replaced bpv w/OEM, bulletproofed tmic which fixed the minor leak. pressure tested to 10psi with no leaks. RESULTS What has and hasn't worked for you: The torn inlet was a big problem, but stuttering still is present. Nothing has worked at this point. I am experiencing a lot of feedback knock at low throttle/low rpm which doesn't make sense. I have no knocking under WOT. I've check probably a half dozen times for something loose or bouncing around to cause the knock, but I haven't found anything. If something worked, how long has it been working for: Nothing has worked at this point. I've been suggested to replaced my upstream o2 sensor regardless of having no codes; does that seem like a good idea? please help! Clean your throttle body. It worked for me. Sent from my LG-E970 using Tapatalk 2 Link to comment Share on other sites More sharing options...
SeeeeeYa Posted November 20, 2013 Share Posted November 20, 2013 Filled my driveshaft hanger bushing with Windo-Weld Polyurethane. Significant improvement in surging issues and overall driveline slack. Been meaning to do this for 5 years. That is impressive, and one of the better pieces of ingenuity you've provided. Wish I'd have thought of it. I used that poly to fill my '05's diff bushings, with a considerable improvement before there were "kits." I also used it to fill the rear LCA bushing, with similar improvements. I've used it elsewhere with success. But I never thought of that one. Link to comment Share on other sites More sharing options...
mwiener2 Posted November 20, 2013 Share Posted November 20, 2013 I might go to town with that stuff and fill my whole car. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
chimera Posted November 21, 2013 Share Posted November 21, 2013 (edited) TYPE OF STUTTER/STUMBLE Steady throttle/Increasing throttle/Both: Pretty much at or just around 5,000 RPM exactly, at WOT, never happened outside this range and only happens in 3rd and 4th (its 5EAT) - but then not always (if it happens in 1st and 2nd, I don't feel it) Generally can reproduce it if I floor it from 1st and take it right up the rev range through all gears. Hit about 5,000rpm's in 3rd and its like someone's turned off the fuel line for a split second. Its an '07 LGT 5EAT MODS Intake: none Exhaust: Catted DP Fuel: 98 Octane (about US 95 equivalent) Turbo: Stock (VF44 I think) Engine Management: Stock ECU Tuner and revision of tune(if you don't mind): Cryo, stage 2. Final revision. MAINTENANCE Sensors changed: Changed O2 sensor Plugs changed: 10,000km's ago Coil Packs changed: Not tried OTHER SYMPTOMS Check Engine Light: Never Etc: Car runs perfectly otherwise RESULTS What has and hasn't worked for you: O2 sensor replaced. That *seemed* to work for a while, but then came back straight after flashing an ECU revision. May have been coincidence. Reverting the revision did not sort it (although possibly cooked the O2 sensor again? Unlikely?) Its in getting a service right now and the auto electrician just rang said that their diagnostic tool showed a error code on the TCU - he reset it, in-case it caused an issue. Unsure what the error was, but I'll try driving again when I pick it up. I'm not confident that it will resolve though. Edited November 21, 2013 by chimera Link to comment Share on other sites More sharing options...
cryo Posted November 21, 2013 Share Posted November 21, 2013 I remember catalyst had a very similar issue and it turned out to be his silicone intake collapsing at about 5200rpms causing a huge power surge like you describe. The TCU thing is interesting based on what we were seeing with the weird rpm behavior during the pulls. Dave [sIGPIC][/sIGPIC] Providing unmatched customer service and a Premium level of Dyno/E-tuning to the Community cryotuneperformance@yahoo.com facebook.com/cryotuneperformance. Link to comment Share on other sites More sharing options...
adrenalinecrisis Posted November 21, 2013 Share Posted November 21, 2013 Update: I cleaned my throttle body and no improvement Link to comment Share on other sites More sharing options...
heiche Posted November 21, 2013 Share Posted November 21, 2013 Filled my driveshaft hanger bushing with Windo-Weld Polyurethane. Significant improvement in surging issues and overall driveline slack. Been meaning to do this for 5 years. good idea! have you noticed any increase in nvh? any pics? BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT Link to comment Share on other sites More sharing options...
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