LandShark Posted December 3, 2004 Share Posted December 3, 2004 Comrades, I started noticing a slight but annoying "lurch" in my drivetrain recently. I have the 5MT sedan. It only seems to happen when I'm cruising typically on the highway in 4th gear and in the neighborhood of 4-5 K rpm. The "lurch" happens when I push the gas peddle hard for max. acceleration but without a downshift. The drivetrain just hesitates for about a quarter-second and then there's a noticably "lurch" as it moves forward. I don't notice any disconnect in the drivetrain under any other conditions. I love how "tight" the Subaru drivetrain seems to be. You push the gas - the car move NOW! I'd like to know if anybody else has experienced this sort of hesitation? This is NOT the low-speed thing. I'm talking about a "lurch" when you motoring along at about 75 mph and try to accelerate hard without shifting. Or if any of you hardcore know-it-alls have some ideas of what this might be based on my description - I'd like to hear it. And yes, I do drive my LGT hard but not in a damaging way. I just like to use all the power it has most of the time. And I've got about 6,500 miles on it now. Link to comment Share on other sites More sharing options...
SBT Posted December 3, 2004 Share Posted December 3, 2004 Running aftermarket wheels? I only ask because I had this problem with as set of AMs a while back and did the same thing. Once I swapped back to stock, problem gone. I was not using hub-centric rims at the time and it was causing enough of a shift along the axial line to notice. Other than that, it's probably an unworked deficit of the ECU/FBW setup. Is it repeatable? Does the engine gasp, stutter or otherwise contribute to this or do you feel like it was in the drivetrain? SBT - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
LandShark Posted December 3, 2004 Author Share Posted December 3, 2004 Unfortunately, NO, I'm running all stock gear except a lightweight crank pulley. I sure don't think that's the culprit. It does not feel like an engine hesitation but rather a true "looseness" in the drivetrain. Perhaps a better description other than lurch would be "jerk" because there's a physical aspect to it. What I'm saying is.....it's not that the response is hesitant in the engine revving when the gas peddle is pressed but rather a slight delay between the engine revving and the car moving ahead. Like I say, it's only about a quarter-second delay. In all other circumstances the whole engine-drivetrain connection seems so seemless and instantaneous. No disconnect at all. That's part of what I love about this car. It almost feels like an electric powered vehicle. Push the peddle down and it GOES LIKE STINK! My biggest worry is that I never noticed this in the first 5,000 miles of driving although my driving style has remained consistent (and agressive) all along. I did honor the first 1,000 mile breakin for the most part. I guess I should just monitor it and see if the lurching get progressively worse. Link to comment Share on other sites More sharing options...
SBT Posted December 3, 2004 Share Posted December 3, 2004 If you can repeat it, start cataloging when it does it, under what circumstances, e.g., WOT, off-WOT - back on, gear range(s)/RPMs it occurs, etc. Sounds like it was significant enough at the time to get your attention, but it could just be a transient aberration. If it persists, then get it checked out. Just be able to replicate the what and when of it. Otherwise, relax and enjoy the wonderful ride. SBT - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
LandShark Posted December 3, 2004 Author Share Posted December 3, 2004 Will do! Still interested if any other LGT drivers have noticed a similar situation. Link to comment Share on other sites More sharing options...
Guest *Jedimaster* Posted December 3, 2004 Share Posted December 3, 2004 I'm thinking this is an issue with the drive by wire throttle. It's the same kind of thing as in the hesitation mentioned elsewhere right? I believe the COBB reflash will fix it and that Shiv guy has already verified that his reflash fixed it. Link to comment Share on other sites More sharing options...
Deer Killer Posted December 3, 2004 Share Posted December 3, 2004 I notice a ~half second DBW delay always. The latency has gotten better after a few thousand miles, but the few thousand miles are on ME, not the car. I just compensate for it subconciously. It still sticks out like a sore thumb for example on a spirited 1-2 shift where I'm not really paying attention to the car. Then the 1/2 second latency usually results in 1/2 second bog at the begining of second (even though my feet are right on). I need to time back-on-the-gas before I've finished shifting for a really smooth shift. The "NOW" feeling I think happens because of the rush of torque not the pedal->engine timing. That's one of the things I really liked about the car. However if you play with it on the highway for example you can still see the same amount of latency from input to reaction. Perhaps you're expecting it to do something it doesn't want to do? I really need to go drive some other subaru DBW cars and see if they all do the same thing. I find it hard to believe more people don't notice. Perhaps a decade of playing networked high-response FPS's has just made me more sensitive to latency. Link to comment Share on other sites More sharing options...
Deer Killer Posted December 3, 2004 Share Posted December 3, 2004 [quote name='jedimaster']I'm thinking this is an issue with the drive by wire throttle. It's the same kind of thing as in the hesitation mentioned elsewhere right? I believe the COBB reflash will fix it and that Shiv guy has already verified that his reflash fixed it.[/QUOTE] Eh, the latency? no, just the map problems switching from closed to open loop parameters. I asked shiv about it on i-club and he didn't respond. Link to comment Share on other sites More sharing options...
emlevins Posted December 3, 2004 Share Posted December 3, 2004 [quote name='LandShark']Comrades, I started noticing a slight but annoying "lurch" in my drivetrain recently. I have the 5MT sedan. It only seems to happen when I'm cruising typically on the highway in 4th gear and in the neighborhood of 4-5 K rpm. The "lurch" happens when I push the gas peddle hard for max. acceleration but without a downshift. The drivetrain just hesitates for about a quarter-second and then there's a noticably "lurch" as it moves forward. I don't notice any disconnect in the drivetrain under any other conditions. I love how "tight" the Subaru drivetrain seems to be. You push the gas - the car move NOW! I'd like to know if anybody else has experienced this sort of hesitation? This is NOT the low-speed thing. I'm talking about a "lurch" when you motoring along at about 75 mph and try to accelerate hard without shifting. Or if any of you hardcore know-it-alls have some ideas of what this might be based on my description - I'd like to hear it. And yes, I do drive my LGT hard but not in a damaging way. I just like to use all the power it has most of the time. And I've got about 6,500 miles on it now.[/QUOTE] It has happened to me too and it is what I (and what others I think) have described as the studdering problem. I've had it in low RPM and I've had it cruising on the highway without downshifting as you have. And, I have also had it on the highway when downshifting (from 5th to 4th and then hitting the throttle hard). It all seems the same to me - "the" studder... 05 SWP Legacy GT Limited (aka "Pearl")- 5MT AP - Stage 2 Protuned (238/284) - wife driven 07 BMW 335xi Link to comment Share on other sites More sharing options...
LandShark Posted December 3, 2004 Author Share Posted December 3, 2004 I hope it's true that this high-speed hesitation is coming from the same cause as the low-speed one. I've read a few posts on drivers that have reflashed the ECU and it seems to cure it, at least the low-speed one. I am planning to buy a Cobb AP in about a month. Hopefully, everything will be better once the optimized map is flashed in. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.