tallen702 Posted December 5, 2016 Share Posted December 5, 2016 Hello everyone. I recently went through the hell of dealing with the 16-90-13R and 16-95-15 TSBs with my 2012 Legacy 2.5i Premium w/ CVT. I had the stall issue start just before the transmission squeal noise kicked in at 110k miles and spend the better part of 2 months dealing with two dealerships and an indpendent factory-trained mechanic to finally get the answers I needed to get everything squared away. Ultimately, I wound up putting a new-model torque converter and new solenoid valve body onto a used 40k mile CVT transmission core and had it put in. No more transmission squeal, no stalling at hard stops, and you can sense when the TC unlocks right around 20mph when slowing down. That seems to be done and dusted, but I'm having an issue where sometimes, on a slight incline at a specific stoplight near me, the engine idle will roughen up a bit and the tach will drop to near the 500rpm mark for a split second before recovering. It's not the torque converter issue because it doesn't happen as I'm coming to a stop, but rather 30 seconds to a full minute afterwards. I figure it's something with the engine management system and not the transmission, but could the torque converter be trying to lock up while at idle? Or are there systems other than just the signal from the Transmission Control Module that control when it decides to lock and unlock? Lastly, anyone have a similar experience and have a cure? Dealers are stumped (of course, it took one dealer 2 weeks to finally come to the conclusion that yes, my CVT chain was indeed slipping on the pulleys) and independent mechanic hasn't heard of a similar issue at this time after a full transmission replacement. Thanks in advance! Link to comment Share on other sites More sharing options...
GTEASER Posted December 5, 2016 Share Posted December 5, 2016 Are you sure it's not the AC compressor kicking on? 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...
tallen702 Posted December 5, 2016 Author Share Posted December 5, 2016 Are you sure it's not the AC compressor kicking on? Yeah, neither the AC or the Defrost have been on during at least one of the time. It's very similar to the same kind of drag I get if at idle and try locking all the doors when they're already locked. It seems to happen after short runs (probably 3-4 miles) after having sat for a bit before driving. My thought was to have the dealership re-flash the TCM/ECU just to be on the safe side? Link to comment Share on other sites More sharing options...
GTEASER Posted December 5, 2016 Share Posted December 5, 2016 A reflash wouldn't be a bad idea. 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...
Golferdude1087 Posted December 5, 2016 Share Posted December 5, 2016 Could the throttle body be exceptionally dirty? I mean after the car has gone 100k miles there will be carbon buildup and most likely during the work they removed the battery longe enough to force an ECU reset. Over time the ECU can adjust for the change but right away its going to choke because its expecting ideal conditions. I just had this happen with my wifes 07 impreza and we weren't expecting it at all so it was a surprise when she started stalling on slight inclines randomly. Link to comment Share on other sites More sharing options...
ehsnils Posted December 6, 2016 Share Posted December 6, 2016 An old engine means a lot of stuff that can get gummed up, also check the PCV valve. A data log might also help understanding the issue. Link to comment Share on other sites More sharing options...
dgoodhue Posted December 6, 2016 Share Posted December 6, 2016 I don't know how long you have had your car, but my 2.5i since new has occasionally had a stumble when slowing down at idle. It seem to be more prevalent at different times of the year. If you look at the tach when it happens it seems to drop about 25rpm or so during the incident but it 'feels' like its dropping a lot more than that. If you search on the subject, their are other owner '10-12 (2.5i EJ253 motor) with this issue. I think its more ECM calibration that Subaru chose an idle speed as low as possible. Their is no fix that I am aware of. Link to comment Share on other sites More sharing options...
tallen702 Posted December 6, 2016 Author Share Posted December 6, 2016 Yeah, dirty throttle body was a thought for me. It's had about 1500 miles put on it since the transmission swap though, I'd have thought that would be enough for the ECU to re-learn everything, but maybe not? The car is paid off in a couple more months, so I think I'll see what happens between now and then, and then have my local mechanic (the Subie specialist who did the swap) give her a good run-down. Thanks for the replies everyone! Link to comment Share on other sites More sharing options...
tallen702 Posted December 6, 2016 Author Share Posted December 6, 2016 I don't know how long you have had your car, but my 2.5i since new has occasionally had a stumble when slowing down at idle. It seem to be more prevalent at different times of the year. If you look at the tach when it happens it seems to drop about 25rpm or so during the incident but it 'feels' like its dropping a lot more than that. If you search on the subject, their are other owner '10-12 (2.5i EJ253 motor) with this issue. I think its more ECM calibration that Subaru chose an idle speed as low as possible. Their is no fix that I am aware of. Yeah, it's not necessarily a new thing. It had happened in the past as well, but I chalked that up to the bad TC since the early symptoms of that going are a similar rough-idle/near stall as well. I guess I'm being overly suspicious due to having just dropped 4k into the sucker for repairs due to a bad design on Subaru's part with the TC. Apparently I'm a lightning rod for bad Subies. My '03 2.5RS came from the factory with a transmission shaft bearing packed in grease instead of gear oil. 3rd gear coming down Snowshoe Mountain in WV with only 300 miles on the car when I hear a loud bang and suddenly hear grinding metal from under my feet. Subaru repaired that (new transmission and drive shaft). Then my folks had an outback with the head gasket issue. Now this transmission failure and low/rough idle issue. Ugh.... Link to comment Share on other sites More sharing options...
nads Posted December 6, 2016 Share Posted December 6, 2016 Tune up? Have you changed the plugs, inspected the coil packs, PCV (as stated earlier) cleaned the battery terminals and wire ends, checked the alternator, water pump, ac and idlers for excessive drag, replaced air fliter, cleaned MAF sensor, possible cleaned the air idle control valve (if the engine has one). Is the engine fully warm when this happens? Link to comment Share on other sites More sharing options...
brandon.mol Posted December 6, 2016 Share Posted December 6, 2016 My car was doing something similar.. in my case it was the rad fans kicking on. Increasing my idle RPM by just 25 RPM completely resolved it. YMMV Link to comment Share on other sites More sharing options...
tallen702 Posted December 8, 2016 Author Share Posted December 8, 2016 Tune up? Have you changed the plugs, inspected the coil packs, PCV (as stated earlier) cleaned the battery terminals and wire ends, checked the alternator, water pump, ac and idlers for excessive drag, replaced air fliter, cleaned MAF sensor, possible cleaned the air idle control valve (if the engine has one). Is the engine fully warm when this happens? Plugs, coil pakcs, battery terminals and wire ends, alternator all checked recently. Water pump, tensioners and belts all replaced just a few thousand agao. Air filter is new, MAF likely needs cleaned. PCV hasnt' been check that I know of. Did the 105k maintenance just 5k ago. Link to comment Share on other sites More sharing options...
tallen702 Posted December 8, 2016 Author Share Posted December 8, 2016 My car was doing something similar.. in my case it was the rad fans kicking on. Increasing my idle RPM by just 25 RPM completely resolved it. YMMV I think this actually might be part of it. As I said earlier, it seems to happen after a short drive when the car has been sitting for just a bit. Probably load on the engine combined with the low idle and likely some gunked/dirty parts/sensors given the mileage. Link to comment Share on other sites More sharing options...
nads Posted December 9, 2016 Share Posted December 9, 2016 So you good on maintenance. The cooling fans are a good call, could possibly be one going south and its dragging the system down. Link to comment Share on other sites More sharing options...
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