Phillip J. Fry Posted May 11, 2016 Share Posted May 11, 2016 Could be, if auto it could be shifting past the stumble before you notice it, or if auto is choppy anyway. At first I didn't get the stumble either, it took me finding an uphill road (plenty of them here) and forcefully keeping RPM's at 2.5-3k, since I usually am at 2k rpm thus below the stumble zone. next time i come up the hill from the ferry dock i will try this . 2500-3000rpm. does gear matter? Link to comment Share on other sites More sharing options...
covertrussian Posted May 11, 2016 Share Posted May 11, 2016 Usually it was in 2nd gear for me, there is also a load range that's still unknown (I think this is why hills where able to trigger it for me). 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
m sprank Posted May 12, 2016 Share Posted May 12, 2016 Its an RPM/load. 2.5k to 3k with a slight incline usually triggers it. None of my own cars have ever shown the stumble. But I have lots of logs showing it happen in customers cars. Link to comment Share on other sites More sharing options...
xtea Posted May 12, 2016 Share Posted May 12, 2016 Its an RPM/load. 2.5k to 3k with a slight incline usually triggers it. None of my own cars have ever shown the stumble. But I have lots of logs showing it happen in customers cars. Before my engine blew this is exactly how I would have described it. Hoping the new engine comes without this quirk. Link to comment Share on other sites More sharing options...
Phillip J. Fry Posted May 12, 2016 Share Posted May 12, 2016 Before my engine blew this is exactly how I would have described it. Hoping the new engine comes without this quirk. id argue its not the engine itself. the long block i mean. something auxiliary. aka the fpr some are saying. theoretically if it is something auxiliary and it gets taken from the old engine and installed onto the new one you may have the same issue. Link to comment Share on other sites More sharing options...
Nightmaresmk Posted May 12, 2016 Share Posted May 12, 2016 Mine did it with the factory fuel system on a stg2 protune by Bren. new system with iag rails, pulse dampeners, id1k and aeromotive FPR zero stumble. Link to comment Share on other sites More sharing options...
Max Capacity Posted May 12, 2016 Share Posted May 12, 2016 (edited) My 09 Spec B has it on the highway climbing hills. Very slightly. No one else in the car can feel it, only me when the rpms at 2400-2600. It goes away about 3000rpm. Edited June 7, 2016 by Max Capacity 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 Link to comment Share on other sites More sharing options...
oncesir Posted May 14, 2016 Share Posted May 14, 2016 It will always come back as the ECM learns. The trick is to stop the ECM learning in the specific blocks required. You need to extend the fuel lines and source a manifold reference point for the FPR (not a single runner, but the plenum). No need to replace the FPR. Took your advice and ran a plenum source for the fpr. I didn't reset the Ecu and went for a drive. Immediately I noticed less of the stumble. How do you stop the Ecu from relearning the stumble? I have the sti fpr right next to me and it's tempting to install just for simplicity sake. TIA Link to comment Share on other sites More sharing options...
heiche Posted May 14, 2016 Share Posted May 14, 2016 Took your advice and ran a plenum source for the fpr. I didn't reset the Ecu and went for a drive. Immediately I noticed less of the stumble. How do you stop the Ecu from relearning the stumble? I have the sti fpr right next to me and it's tempting to install just for simplicity sake. TIA If you install the sti fpr along with your relocated fpr signal to the plenum, you may not have a stumble to worry about ymmv 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 May 14, 2016 Share Posted May 14, 2016 Took your advice and ran a plenum source for the fpr. I didn't reset the Ecu and went for a drive. Immediately I noticed less of the stumble. How do you stop the Ecu from relearning the stumble? I have the sti fpr right next to me and it's tempting to install just for simplicity sake. TIA I would recommend contacting a professional tuner for assistance in that matter. But, there is free software that can be used to do it. I have had some cars where the owners no longer felt any stumble with just the mechanical fixes. We got into the tuning side of the fix quite a bit after the mechanical side as it seemed to work for many customers. Link to comment Share on other sites More sharing options...
oncesir Posted May 14, 2016 Share Posted May 14, 2016 I would recommend contacting a professional tuner for assistance in that matter. But, there is free software that can be used to do it. I have had some cars where the owners no longer felt any stumble with just the mechanical fixes. We got into the tuning side of the fix quite a bit after the mechanical side as it seemed to work for many customers. The car was etuned by Cryotune last yr. I decided I'm going to put some miles on the reset Ecu and see what happens. I'll report back shortly. Thanks guys. Link to comment Share on other sites More sharing options...
NSFW Posted May 31, 2016 Share Posted May 31, 2016 Its an RPM/load. 2.5k to 3k with a slight incline usually triggers it. None of my own cars have ever shown the stumble. But I have lots of logs showing it happen in customers cars. Which parameter(s) show the stumble in logs? My car had a tiny amount of stumble so I didn't look into it much. But I see so much discussion of it, I can't help but be curious. Mine went away completely with a new motor but that's a prohibitively expensive way to tackle the problem. Link to comment Share on other sites More sharing options...
m sprank Posted June 1, 2016 Share Posted June 1, 2016 You can catch it in the fuel trims if you know what you are looking for. When the car attempts to learn around the stumble then it becomes much more evident. Link to comment Share on other sites More sharing options...
covertrussian Posted June 1, 2016 Share Posted June 1, 2016 Now that I was paying attention I did notice a stumble, but now at 2k rpm only. I'll do a log next time and see if it's trying to learn around it. 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
quick4dr Posted June 1, 2016 Share Posted June 1, 2016 The car was etuned by Cryotune last yr. I decided I'm going to put some miles on the reset Ecu and see what happens. I'll report back shortly. Thanks guys. any progress? Link to comment Share on other sites More sharing options...
oncesir Posted June 3, 2016 Share Posted June 3, 2016 any progress? Nope. Stumble is still there. Gonna try the Sti FPR and see how it does. Ill update shortly. Link to comment Share on other sites More sharing options...
oncesir Posted June 17, 2016 Share Posted June 17, 2016 Installed the Sti FPR and reset the ecu about a week ago. Ive been driving around hoping that the stumble didnt return and so far so good. Sending logs to Dave @ Cryotune shortly and will report back. Overall the car feels so much smoother at the usual stumble rpm of 2500-3000. I did notice that the Sti FPR is a bit noisey on startup for some reason. It goes away once the engine is revved fwiw. Not concerned about a bit of noise for smooth driveability though. One thing I noticed and experimented with was that after I installed the Sti FPR I didnt reset the ecu. The stumble was still noticeable. After resetting everything the car has actually gotten smoother as I have put miles on it. Granted, there is a small stumble from time to time but this is a Subaru after all... Overall I'm happy with things. A huge thanks to all those involved in this thread. Link to comment Share on other sites More sharing options...
heiche Posted June 17, 2016 Share Posted June 17, 2016 I noticed that noise a little too. Sort of like you can hear the fuel whooshing through the regulator at idle. Seems like it only happens when the fuel pump is at 33% duty cycle (idle for example), as soon as you hit the throttle it disappears. But like you, I think it was a minor inconvenience, and because racecar (palindrome) and all that. 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...
FJuan Posted June 20, 2016 Share Posted June 20, 2016 I took off the upper fuel line before and added a larger fuel line. Did notice better response without major stumble, a little better than before. The only problem I had is the fuel line would blow off because I didn't had it connected over the crimped side of the fuel rail line. Going to give it a try again tonight with securing the front and back of the crimp line to help secure it better. Getting tired of my car going in/out of "limp" mode because of it. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
FJuan Posted June 21, 2016 Share Posted June 21, 2016 Install a new fuel line and this time I pushed over the crimped side and clamped it on both sides. Ran it around last night and felt better, smoother. This morning it ran even better when it popped out of "limp" mode. If the "limp" mode comes back in a week, I know it's related to something else. Otherwise, the car ran great with very very little stumble. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
Max Capacity Posted October 12, 2016 Share Posted October 12, 2016 Bump to the top. 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 Link to comment Share on other sites More sharing options...
kzr750r1 Posted October 12, 2016 Share Posted October 12, 2016 I had completely forgotten about this mod. Since the rebuild I have yet to experience this stumble. Was usually feeling it running up hill on the freeway. Not clear yet if it's the new HW or the current tune. Only fuel change made was the new DW65C pump. Link to comment Share on other sites More sharing options...
Max Capacity Posted October 12, 2016 Share Posted October 12, 2016 Here's pic's of what I did. Here's the area we're talking about, http://i185.photobucket.com/albums/x40/92Si/DSCN7065_zpsnuqhll3d.jpg Here's my take. http://i185.photobucket.com/albums/x40/92Si/DSCN7341_zpsroninchk.jpg http://i185.photobucket.com/albums/x40/92Si/DSCN7339_zpsizg2evto.jpg Updating this because of photobucket... 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 Link to comment Share on other sites More sharing options...
heiche Posted October 12, 2016 Share Posted October 12, 2016 Looks good, Max. Much smoother signal to the FPR this way, rather than the pulsations of the stock location. 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...
GTEASER Posted October 12, 2016 Share Posted October 12, 2016 Max, so you just ran the FPR vac line from the FPR to the BPV signal hose instead of the stock location on the manifold? GTEASER's 2012 Legacy GT - Sold GTEASER's 2009 XTeaser - Sold GTEASER's 1992 Legacy SS - Sold Link to comment Share on other sites More sharing options...
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