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Old 08-11-2010, 04:49 PM   #1
Travisty
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Default 2.5i rev's take forever to fall during shifting.

Hey guys. I've tried searching, but I haven't come up with any results pertaining to my odd situation. My car is an '08 2.5i with a manual. The car has NO mods, other than a resonator delete and a melon cannon.

The problem I'm having is shifting smoothly; more specifically, upshifting smoothly. The car's RPM don't seem to drop for crap when I pull in the clutch for an upshift. They stay elevated so high, that I normally drop ~500 RPM as soon as I let the clutch out. I know that's not a HUGE issue, but it bothers me and makes for some rather embarrassing "shaky" shifts. I know some of it is the fact the car has a hydraulic clutch and that takes away some of the "feel", but the rev matching sucks.

Now, here's how I KNOW the rev matching is messing me up. If I put a load on the car, something that will drop the revs more quickly (like the defroster), they drop right in sync with my shifting habits and it's smooth as butta'. Is it just something I'm going to have to get used to, or is there a parameter I can have tuned?

Also, what's up with the way the car tries to rev match with the clutch in? If I stay in first gear rolling through a shopping center and come up to a stop sign and pull in the clutch a while before I get there and leave it in gear (doesn't matter what gear), it will drop revs, then pick them right back up, and kind of rev the engine within a 3-500rpm range, presumably trying to get close to what the engine "should" be at if the clutch were out. Is there a way I can tune that out too? It's annoying as piss having to pull the car out of first, come to a stop, then thump it back in gear...

I'm sure Subaru tried to make these manual cars extremely newbie friendly by doing all of this, but for a purist, it's straight up maddening.

Any help guys? Thanks.
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Old 08-11-2010, 05:21 PM   #2
chazly413
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Just something you're gonna have to get used to. One tip is to take your foot completely off the gas before you put the clutch, this will make the revs drop quicker. I've found the revs fall a little too quickly for my liking when I do that, though, so I get off the gas a hair of a second after I put the clutch in, so I'm not slamming gears (bit of an exaggeration but I don't wanna move the shifter around really quickly) to hit the rev match.

Another option is that you could get a lightweight flywheel/pulley. This will also make your revs drop faster due to a lower moment of inertia.

I also have the problem with the revs spiking up when coming to a stop, but it's weird with me; it doesn't always happen. I've tried searching and asking for solutions to this problem but I've never found out anything. Someone on here probably has an idea, though.
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Old 08-11-2010, 05:26 PM   #3
Travisty
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Originally Posted by chazly413 View Post
Just something you're gonna have to get used to. One tip is to take your foot completely off the gas before you put the clutch, this will make the revs drop quicker. I've found the revs fall a little too quickly for my liking when I do that, though, so I get off the gas a hair of a second after I put the clutch in, so I'm not slamming gears (bit of an exaggeration but I don't wanna move the shifter around really quickly) to hit the rev match.

Another option is that you could get a lightweight flywheel/pulley. This will also make your revs drop faster due to a lower moment of inertia.

I also have the problem with the revs spiking up when coming to a stop, but it's weird with me; it doesn't always happen. I've tried searching and asking for solutions to this problem but I've never found out anything. Someone on here probably has an idea, though.
Foot is full off the throttle. I've even experimented with letting the car decelerate slightly before engaging the clutch, but the car still holds the RPM high for about half a second before letting it fall.
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Old 08-11-2010, 05:54 PM   #4
IanB
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Sounds like the drive-by-wire may be causing this, nothing a tune couldn't fix. I HATE DBW with manual transmissions, my Dad's '06 TL Dynamic does the same thing, very annoying.
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Old 08-11-2010, 06:02 PM   #5
wmdoucette
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Quote:
Originally Posted by chazly413 View Post

Another option is that you could get a lightweight flywheel/pulley. This will also make your revs drop faster due to a lower moment of inertia.

I also have the problem with the revs spiking up when coming to a stop, but it's weird with me; it doesn't always happen. I've tried searching and asking for solutions to this problem but I've never found out anything. Someone on here probably has an idea, though.
My 07 wagon started doing this a while ago around 75000km. The light pulley doesn't make much of a difference. Need to take it off so I can take it to the dealer and say "fix it."

I'll post up the results.
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Old 08-11-2010, 07:02 PM   #6
chazly413
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Foot is full off the throttle. I've even experimented with letting the car decelerate slightly before engaging the clutch, but the car still holds the RPM high for about half a second before letting it fall.
Hmm, sounds like you may have a little quirk in the tune. I'd try an ECU reset, might as well. When I take my foot full off the throttle, my revs drop a lot more quickly than how I usually shift.
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Old 08-11-2010, 09:27 PM   #7
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You may have a sticky Idle Air Control valve. Try spraying some carb cleaner through it while the engine is running. For a long-term fix you might want to remove the IAC valve and "exercise" it after spraying the works with WD-40. Mine got sticky at around 60k miles but it's been working well for 17k miles since I treated it.
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Old 08-11-2010, 10:32 PM   #8
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Quote:
Originally Posted by ronemus View Post
You may have a sticky Idle Air Control valve. Try spraying some carb cleaner through it while the engine is running. For a long-term fix you might want to remove the IAC valve and "exercise" it after spraying the works with WD-40. Mine got sticky at around 60k miles but it's been working well for 17k miles since I treated it.
DBW cars don't have IACVs, their idle is controlled by the throttle. The human isn't in control of the throttle, the computer is. Hence the need for tuning...
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Old 08-12-2010, 12:41 PM   #9
BrownyHound
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I've been having this same problem in my '10 OBS. I thought maybe i just sucked at driving a stick, because this is my first manual car and i've only had it for a little over a month. I found that if you push the clutch in, and wait half a second before shifting, it helps the revs drop a little more.

But even then, it's not very consistent. It could just be that my clutch-shift timing is inconsistent, but the bottom line is that it's very hard to get smooth shifts.
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Old 08-12-2010, 01:44 PM   #10
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The drive by wire stuff can be a little goofy. It's certainly a little different than cable driven when driving the car.

You might want to head off to the dealer and ask them to check it out. They may have a reflash available for you if there was a technical bulletin out for it.
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Old 08-12-2010, 05:25 PM   #11
mctwin2kman
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That is weird. My 2007 is stick and DBW and the revs drop fairly quick. Check with the Dealer and see if maybe there is a software update for the ECU that needs done.
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Old 08-13-2010, 05:57 AM   #12
Travisty
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Quote:
Originally Posted by BrownyHound View Post
I've been having this same problem in my '10 OBS. I thought maybe i just sucked at driving a stick, because this is my first manual car and i've only had it for a little over a month. I found that if you push the clutch in, and wait half a second before shifting, it helps the revs drop a little more.

But even then, it's not very consistent. It could just be that my clutch-shift timing is inconsistent, but the bottom line is that it's very hard to get smooth shifts.
I normally do the same thing; abnormally long shift times do help, but then it's normally a guess as to where the RPM is and my roadspeed (because I'm decelerating), so the shift can end up too late and be jerky anyways.. It's such a random thing! I'm really not liking this DBW thing, the throttle delay seems excessive to me as well... It's sad when your 250k mile Nissan Sentra feels more peppy than your new "big block" car.

Will the dealer charge me to look at the car and see if there is a new reflash available? I don't have the kind of money Stealerships require..

Last edited by Travisty; 08-13-2010 at 05:58 AM. Reason: Bad Spelling
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Old 08-13-2010, 09:38 AM   #13
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Here we go again.....


There is no problem with your car it is doing what it was programmed to do: hold RPM so you have better shifts.

The same theory of rev matching downshifts applies here: the more similar RPMs btwn the engine and gearbox the less stress on the synchros and easier shifting.

You can have this feature TUNED out however it isn't a flaw it doesnt hurt your car resetting your ecu WONT fix it. Something you will have to get used to
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Old 08-13-2010, 12:52 PM   #14
chazly413
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^ I think it's something else because if I let off the gas before I put my clutch in, my revs don't hang at all. I make my RPMs hang when I shift by clutching in right before I let off the gas. OP let's off the gas and then clutches in and they still hang. Unless this is a new thing.
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Old 08-13-2010, 02:08 PM   #15
Travisty
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^ I think it's something else because if I let off the gas before I put my clutch in, my revs don't hang at all. I make my RPMs hang when I shift by clutching in right before I let off the gas. OP let's off the gas and then clutches in and they still hang. Unless this is a new thing.
Yeah, but you have an '05 RS. I know they changed a bunch in those 3 years, so maybe that's the difference.

GEE: Thanks man, you answered what I was asking. I only wanted to know if it was programmed that way or if there was a fault.

I was worried about leaving it that way because of jerky shifting and letting the clutch out while the revs were still high (like my OP said, 500-ish), and that's obviously wearing on the clutch. I guess time will tell if that severely shortens the life of the clutch or not.

I've been driving manuals long enough that shifting in the time it takes the motor to drop revs manually isn't a problem, but getting used to this "easier" way to shift is taking some time.

Thanks guys.
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Old 08-13-2010, 02:29 PM   #16
wmdoucette
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Quote:
Originally Posted by GEE-OTTO View Post
Here we go again.....


There is no problem with your car it is doing what it was programmed to do: hold RPM so you have better shifts.

The same theory of rev matching downshifts applies here: the more similar RPMs btwn the engine and gearbox the less stress on the synchros and easier shifting.

You can have this feature TUNED out however it isn't a flaw it doesnt hurt your car resetting your ecu WONT fix it. Something you will have to get used to
So mine is programmed to drop to 1000, then bump itself back up to 15-1700 for 10 seconds? Seems like if it was programmed that way, it would have done it since new, instead up showing up just recently.

On the bright side, if you're too lazy to bother with the clutch, this doesn't affect you at all!
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Old 08-13-2010, 11:47 PM   #17
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It has nothing to do with helping you shift. The TBW cars keep you from pushing too much unburnt fuel through the cat/exhaust by not letting the TB snap shut at high RPM. It keeps a touch of throttle in even when you don't for a controlled over-run.

Annoying as hell, yes. Broken, no. I haven't seen anyone address this specifically in a tuning option, I'll see if a light weight pulley helps when I do my timing belt soon.
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Old 08-14-2010, 07:51 PM   #18
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It's an artifact of programming. It comes from several different sources. One is a delay built in to make it easier for noobs to get it into the next gear before the engine slows down. This is a relatively small factor in the overall picture. There is nothing you can do about this in the tune. Another major issue is that the ECU keeps the throttle slightly open and dumps a lot of fuel into the engine before it finally goes to 0-fuel/0-throttle in order to improve the function of and to protect the catalytic converter. This is a bigger effect than the reaction delay. There is nothing you can do about this in the tune. The final, and largest, part of the picture is that the throttle mapping is absolutely stupid. Fully half of your gas pedal travel doesn't do jack ****. From half way down to on the carpet doesn't change what the physical throttle is doing. So you have to pick your foot up off the floor and get it to the half way point before the car even starts to consider closing the throttle. This is a huge time delay compared to the other two issues. This issue, however, can be corrected in the tune.
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