rts Posted May 31, 2005 Share Posted May 31, 2005 Did not find anything on this subject searching the forums. I have a '05 Legacy 2.5i Ltd wagon with automatic transmission. My question. At highway speeds, say 70mph, if you encounter a grade that requires the car to downshift my car seems to bump up revs slightly, say from around 2500 rpm to 3000 rpm briefly (don't know if this is really a downshift or not) then it will downshift into third gear and jump to around 4000 rpm (at about 70 mph). Fine, no problem. The car can take most grades at 70 mph at this rpm which is well below the redline. What worries me is that on occasion ( I guess when the grade is even greater) the car seems to downshift into third gear briefly and then downshifts again, pegging the tach momentarily just under 6000 rpm ( almost red line) and then shifts back down to 4000 rpm almost immediately. Is it normal for this transmission to downshift this aggressively. I guess it is downshifting briefly into second gear when it does this. This seems to happen when cruise control is engaged. I've tried driving these mountain interstates in the sport mode thinking if I manually downshifted it that this would eliminate the brief, high rev, downshift it does on it's own. For the most part this helps but on occasion the car has overridden the manual mode and downshifted itself as explained above. I hope this makes at least some sense. Any thoughts or advice? I guess that since it doesn't actually throw the rpm's into redline it shouldn't be doing any damage but why does it do this when it immediately shifts back to around 4000 rpm and can take the hill easily in this gear at this rpm. Doesn't seem necessary for it to be so aggressive with downshifts under certain conditions. Link to comment Share on other sites More sharing options...
Xantium Posted May 31, 2005 Share Posted May 31, 2005 My sedan does the same thing, the auto tranny is mentally handicapped for lack of a better term, i unplug my battery all the time to make it "forget" what its learned about how i drive.. i usually keep it in tiptronic just so i can control what the car is doing, worst auto ive ever owned. It thinks too much. Link to comment Share on other sites More sharing options...
rts Posted May 31, 2005 Author Share Posted May 31, 2005 Does disconnecting the battery help the aggressive downshifts? Is this something the car "learned", perhaps after doing it once. I don't really understand what or how the car adapts to the driver and how you drive. Besides, every time I would disconnect the battery I would have to re-do the annoying seat belt chime disable thing. What a pain. Link to comment Share on other sites More sharing options...
Edvig Posted May 31, 2005 Share Posted May 31, 2005 The 2.5i has a pretty slow tranny. That combined with the 4 speed gearing, it can get a little jerky on the highway. Link to comment Share on other sites More sharing options...
fbi012 Posted May 31, 2005 Share Posted May 31, 2005 same problem here. and since we're talking about shifting, when Im on tiptronic, do I have to take my foot off gas and shift or doesnt matter? Link to comment Share on other sites More sharing options...
rts Posted May 31, 2005 Author Share Posted May 31, 2005 I don't lift off the gas as you would do with a manual, just bump it up or down a gear. All in all I don't mind the performance of the transmission, I just worry about it downshifting, evidentally two gears, and popping the rpm's up to 6K especially since it is not needed. Downshifting into third will pull any grade I am likely to be on at 70 mph. I don't know if 6K is just what the rpm's are in second gear at 70 mph or if it is the rev limiter kicking in to keep it at 6K. My guess, and it is just a guess, is that since this happens mostly when using cruise control, when the car hits a steep grade the tranny panicks, trying to maintain the set speed. As soon as the engine hits 6K it realizes that is not the answer and shifts into third which is where it should be to begin with. I guess just another addition to the growing list of Subaru's quirky behavior. Link to comment Share on other sites More sharing options...
Xantium Posted May 31, 2005 Share Posted May 31, 2005 I know im not supposed to as the throttle is electronically feathered, but i always lift off the gas when i press up or downshift, doesn't feel right keeping it pinned. Link to comment Share on other sites More sharing options...
Helfrick Posted May 31, 2005 Share Posted May 31, 2005 I always drive in manual mode. I actually try to rev-match mine on the downshift. If you time it right, it is a very smooth transition. In normal auto or sport mode I find the shifting to be too jerky for my tastes. I've never encountered the aggressive downshifting as mentioned in the parent post, but we don't have many grades to worry about down here. Link to comment Share on other sites More sharing options...
mtnsubie Posted June 2, 2005 Share Posted June 2, 2005 i think the manual suggests putting it into sport mode when in the cruise control for hills. otherwise, it's better to put it into manual and use 3rd. this depends on the grade of the hill. this has worked for me. this auto is just ok. it would've been great if it were a 5 spd, of course, but then the price would also reflect that. Link to comment Share on other sites More sharing options...
rts Posted June 2, 2005 Author Share Posted June 2, 2005 These are some pretty good grades. Don't know what % they are but I also have a supercharged Bonneville SSEi that has enough horsepower and touque that it normally never even thinks of downshifting, but it does on a few of these hills. I was just wondering why subaru would design the tranny to downshift two gears under certain conditions. Third has more than enough to pull these hills comfortably at the posted 70 mph so why even go into second even if just for a second before upshifting back onto third. Strange. Last time through there I did use the sport mode with more success, however there are still conditions where the car will override the sport mode and shift anyway. Link to comment Share on other sites More sharing options...
fbi012 Posted June 2, 2005 Share Posted June 2, 2005 I know im not supposed to as the throttle is electronically feathered, but i always lift off the gas when i press up or downshift, doesn't feel right keeping it pinned. but what I meant was when u upshift.. Link to comment Share on other sites More sharing options...
rts Posted September 24, 2005 Author Share Posted September 24, 2005 i think the manual suggests putting it into sport mode when in the cruise control for hills. otherwise, it's better to put it into manual and use 3rd. this depends on the grade of the hill. this has worked for me. this auto is just ok. it would've been great if it were a 5 spd, of course, but then the price would also reflect that. I will be driving the stretch of interstate I have this problem on in about two weeks. I will try the sport mode as well as the manual mode and see if this eliminates the problem I mentioned this problem when I scheduled my last oil change. When the car was done there wasn't anything on the repair order about it. I asked the service manager about this ( the Subaru tech that worked on my car was in the room too) They both said this situation was "normal" and that they "all do that" Now, to me that is no answer. I am concerned that the car redlining itself may damage the engine or at a minimum put undue strain and wear on it. I get no technical explanation as to why this is "normal" or why it won't damage the engine. Anyway, I asked that they reprint my repair order showing my complaint and to put in writing that it is normal. They looked at me as if I were nuts but I persisted and they did do this. Considering I spent the money for a seven year 100,000 warranty I want to be able to show them if the thing blows itself up that I had made them aware of the problem. If I notice this again on my upcoming trip I will ask for it to be checked again when I get my car serviced next. If I still get "they all do it" I think I will contact SOA and see if they feel it is normal. Link to comment Share on other sites More sharing options...
GeorgeB Posted September 29, 2005 Share Posted September 29, 2005 on gears change the engine slighty revs. i noticed this also on my forester 2.5XT . it is kindda normal , so that you get an extra boost for the next gear. Link to comment Share on other sites More sharing options...
eamiller Posted September 29, 2005 Share Posted September 29, 2005 Sounds like pretty normal automatic transmission behavior. Whether you're using the cruise control or not, the pedal position (or what's needed to maintain speed) tells the ECU the requested engine load (usually calculated as a %). It will then calculate the gear/rpm the engine should be at to maintain that load. Depending on the software, the tranny may hold the gear, or be very responsive to downshifting (influenced by sport mode on the Legacy as well). Also, if you're controlling the pedal, you may have a tendency to back off the throttle when you get the 2nd downshift, which will cause the tranny to immediately upshift because you reduced the load request.. This is why auto transmissions and I don't get along. I tend to want the tranny to hold the gear longer and only downshift as a last resort (used to manual transmissions). It seems especially worse on lesser powered cars. The transmissions seems to be programmed to thrash the engine to keep speed up. Link to comment Share on other sites More sharing options...
rts Posted September 29, 2005 Author Share Posted September 29, 2005 Sounds like pretty normal automatic transmission behavior. Whether you're using the cruise control or not, the pedal position (or what's needed to maintain speed) tells the ECU the requested engine load (usually calculated as a %). It will then calculate the gear/rpm the engine should be at to maintain that load. Depending on the software, the tranny may hold the gear, or be very responsive to downshifting (influenced by sport mode on the Legacy as well). Also, if you're controlling the pedal, you may have a tendency to back off the throttle when you get the 2nd downshift, which will cause the tranny to immediately upshift because you reduced the load request.. This is why auto transmissions and I don't get along. I tend to want the tranny to hold the gear longer and only downshift as a last resort (used to manual transmissions). It seems especially worse on lesser powered cars. The transmissions seems to be programmed to thrash the engine to keep speed up. Some good insights. However, in my case we can eliminate the part of controlling the pedal where by backing off or pressing down would cause input to the sensors. In my case, the car is completely being controlled by the cruise control. The transmission is in normal mode, not sport mode. What I find difficult to believe is that the ECU is programmed in such a way that, regardless of the level of performance requested by the cruise control and the capabilities of the engine / transmission to deliver, that it would cause the engine to pass redline, if only by several hundred rpm. My guess is that it is hitting the rev limiter. The equally confusing thing about this, assuming the input received by the ECU indicates the engine has to be at redline and in second gear to deliver the requested level of performance, in fact, is not the case. After this very harsh episode of slamming down two gears and redlining the engine, the ECU tells the tranny to up shift to third gear. In third gear there is more than enough power to maintain the requested speed in third gear running at about 4K. So, if there is sufficient power to deliver the requested performance in third gear, way does the control system insist on selecting second gear over third, if only briefly. Once it realizes it doesn't need second, it goes to third and has more than enough power. Granted, this is the first car I've had in many years with a four cylinder engine and cruise. I am used to cars with much more power than the 2.5i. In fact, I have a Bonneville SSEI with the supercharged 3.8 that doesn't even think of coming out of overdrive on the same road, let alone downshifting. The boost gauge moves up a little but that's all. So, maybe I am just not used to what a smaller engine needs to do in this situation. I still think designing a car that will redline itself can't be good for the engine and drive train. Glad I have 100K warranty!! I have approached my dealer twice on this and insisted they note it on the repair order so I have proof. Both times I get "they all do that" which is the answer (or non answer) I hate most of all. At this point, I have no choice but to accept that this is normal, non destructive behavior. Link to comment Share on other sites More sharing options...
eamiller Posted September 30, 2005 Share Posted September 30, 2005 Keep in mind, the TCU and ECU are separate boxes which are in communication over the vehicle network. The ECU will spit out load requests based on pedal inputs (or cruise control software). The TCU is then free to do as is pleases with downshifts/upshifts. IT does sounds like the software isn't done well in your case, but I have a feeling it's because of the power of the engine (being an 'i' vs. 'GT'), and the fact that the engine makes a good bit of it's power in the upper ranges of the rev band... Also, I've heard of 5EAT owners complaining that the engine will bounce off the rev limiter before the tranny shifts. Sounds like the TCU is commanding too slow of a shift for the change in RPM that the engine is capable of. It is probably choosing shift feel over shift performance (line pressures are commanded by the TCU, which controls how fast and firm the shift is). Link to comment Share on other sites More sharing options...
rts Posted October 22, 2005 Author Share Posted October 22, 2005 Did not find anything on this subject searching the forums. I have a '05 Legacy 2.5i Ltd wagon with automatic transmission. My question. At highway speeds, say 70mph, if you encounter a grade that requires the car to downshift my car seems to bump up revs slightly, say from around 2500 rpm to 3000 rpm briefly (don't know if this is really a downshift or not) then it will downshift into third gear and jump to around 4000 rpm (at about 70 mph). Fine, no problem. The car can take most grades at 70 mph at this rpm which is well below the redline. What worries me is that on occasion ( I guess when the grade is even greater) the car seems to downshift into third gear briefly and then downshifts again, pegging the tach momentarily just under 6000 rpm ( almost red line) and then shifts back down to 4000 rpm almost immediately. Is it normal for this transmission to downshift this aggressively. I guess it is downshifting briefly into second gear when it does this. This seems to happen when cruise control is engaged. I've tried driving these mountain interstates in the sport mode thinking if I manually downshifted it that this would eliminate the brief, high rev, downshift it does on it's own. For the most part this helps but on occasion the car has overridden the manual mode and downshifted itself as explained above. I hope this makes at least some sense. Any thoughts or advice? I guess that since it doesn't actually throw the rpm's into redline it shouldn't be doing any damage but why does it do this when it immediately shifts back to around 4000 rpm and can take the hill easily in this gear at this rpm. Doesn't seem necessary for it to be so aggressive with downshifts under certain conditions. I drove the stretch of interstate again last week that this most often happens on. This time I used the "sport" mode instead of normal drive. This did eliminate the harsh downshifts most of the time. I guess the slightly more aggressive shift points causes the transmission to downshift earlier. The only way to completely eliminate the harsh downshifts was to use the manual mode. As long as you don't wait for ever to shift down to third gear it works well. Link to comment Share on other sites More sharing options...
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