Car Bucks When Shifting.

JoeH · 04-06-2006, 07:35 PM

I just got off the Cobb Stage 2 and every so often the car would buck up and down a half of a second then go every time i shift. nowI just got my new PDX Tuning map flashed in and when i went to kick it, it felt NICE and i hit second and thats all it took. it then bucked like crazy every time i shifted. feeling like the motor hits the ground and kicks back up. I had a set of Group-N engine mounts. tranny mount and pitchstop installed and the buck isnt as bad but its still there and noticeable. Is there anything else i might have to check in replacing to help this problem> or should i have just went the cusco mounts?

jays05 · 04-06-2006, 07:54 PM

Have you replaced any other driveline bushings? The Kartboy rear subframe outrigger bushings and TiC rear diff mount bushings tightened up the driveline in my car a lot.

JoeH · 04-06-2006, 07:59 PM

no not yet, im getting those rear diff bushings put in next week. i havent got the outrigger ones yet. but whats weird is.. i used to be able to drive my car good, no bucking shifts at all clean smooth precise shifts so im not sure if its driver error. maybe i just started tryin to go to quick with my foot off the clutch in shifts ...im not sure...

STi05' · 04-06-2006, 08:19 PM

Quote:

Originally Posted by JoeH

no not yet, im getting those rear diff bushings put in next week. i havent got the outrigger ones yet. but whats weird is.. i used to be able to drive my car good, no bucking shifts at all clean smooth precise shifts so im not sure if its driver error. maybe i just started tryin to go to quick with my foot off the clutch in shifts ...im not sure...

I tend to do that sometimes when im tired... or distracted by something like the lady friend sitting beside me.

But usually its because I let the clutch out too early, which for a moment pushes the motor to the slowing down side of things, then it kicks back to the loaded side.. if THAT makes any sense..

JoeH · 04-06-2006, 08:49 PM

i guess ill have to give it more practice and concentration. but it just seems weird to never bucking to now it bucks 75% of the time.

JoeH · 04-07-2006, 06:43 PM

I just bought the valvoline 75w90 gear oil and some motul rear lsd diff fluid. Im a little behind i dont think its ever been changed and im at 44k.... Damn i hope everything is ok in there.

bzbuzz · 01-02-2008, 01:42 PM

i have very similar problem.. any update these days?

flatthump · 01-02-2008, 01:57 PM

I'm 99.9% sure this is a driving technique issue and not a mechanical one.

C.J. · 01-02-2008, 02:37 PM

This is all in the tune and in relation with drive by wire. I had this problem when my car was stock and also on the OTS cobb stage two map. The only way I would keep the car from doing this was flat foot shifting. I talked to my tuner and during my pro tune he tuned this problem out.

Happy gear bangin!

jermdeez · 01-02-2008, 03:06 PM

If its acting like its hitting a rev limiter could be flat foot shifting.

If it didn't do it before the tune could be a ****ty tune.

Flycaster · 01-02-2008, 04:20 PM

Quote:

Originally Posted by jermdeez

If its acting like its hitting a rev limiter...

Yeah, this was exactly my thinking here. This sounds to me like someone is hitting a fuel cut, either from over-revs, or from overboost. I have a GT30 with none of those bushings or fancy mounts, and I get zero "bucking" - just a whoosh at throttle lift, then the head gets thrown back again with the next gear, and so on.

bzbuzz · 01-03-2008, 06:18 AM

yeh my buckin issue sounds and acts exactly like when there is fuel-cut...but the thing is tho that it started happening when I tried kartboy pitchstop mount...that's when it started..so i replaced it w/ stock one back.. but still remains from time to time...
i have lot of bushing and stuff...i checked the bolts for grp n engine mount that i can check under the car...all seemed fine..but when the weather gets better here i want to check the two nuts that connect the bushing and metal plate..that mite be loose now..
i dunno...i reinstalled grp n tranny mount just in case....the problem is still there..

V8Huntr · 01-03-2008, 09:34 AM

If there are any other STi owners in your area let them drive your car to rule out improper driving technique. But it sound like you may be dumping fuel between shifts. You don't have a BOV do you?

bzbuzz · 01-03-2008, 09:54 AM

Quote:

Originally Posted by V8Huntr

If there are any other STi owners in your area let them drive your car to rule out improper driving technique. But it sound like you may be dumping fuel between shifts. You don't have a BOV do you?

negative..stock bpv..
driving technique doesnt matter since i can duplicate the problem on 2nd gear.. i wot on 2nd gear up to 6k rpm and let off gas...boom..car bucks...
but the enigma is that it doesnt happen all da time...=.=..

La Mer · 01-03-2008, 09:57 AM

This is pretty tough to diagnose over the internet. It could be a few things: Drivetrain, Engine, or ECM.

It might be worth the drive to your tuner since tuners are usually in a shop capable of diagnosing all three areas of your car.

04-06-2006, 07:35 PM	#1
JoeH Junior STI Driver Posts: 93 Join Date: Nov 2005 Trader Rating: (1)	Car Bucks When Shifting. I just got off the Cobb Stage 2 and every so often the car would buck up and down a half of a second then go every time i shift. nowI just got my new PDX Tuning map flashed in and when i went to kick it, it felt NICE and i hit second and thats all it took. it then bucked like crazy every time i shifted. feeling like the motor hits the ground and kicks back up. I had a set of Group-N engine mounts. tranny mount and pitchstop installed and the buck isnt as bad but its still there and noticeable. Is there anything else i might have to check in replacing to help this problem> or should i have just went the cusco mounts? This ad is not endorsed by this member. Please register or login to hide this ad.

01-02-2008, 01:42 PM	#7
bzbuzz STI Driver Car: 06 WRX protuned stag Fav Mod: protune Location: IL Posts: 223 Join Date: Dec 2006 Trader Rating: (1)	Re: Car Bucks When Shifting. i have very similar problem.. any update these days?

01-02-2008, 01:57 PM	#8
flatthump Enginerd Car: The Spaze Mobile Fav Mod: Tuning Location: South O.C., Ca Posts: 12,648 Join Date: Jan 2006 Trader Rating: (5)	Re: Car Bucks When Shifting. I'm 99.9% sure this is a driving technique issue and not a mechanical one.

01-02-2008, 02:37 PM	#9
C.J. Senior STI Driver Car: 06 Aspen/gold STi Fav Mod: Whatever I buy next Location: Lincoln, Ne/Bellingham, W Posts: 386 Join Date: Jan 2007 Trader Rating: (0)	Re: Car Bucks When Shifting. This is all in the tune and in relation with drive by wire. I had this problem when my car was stock and also on the OTS cobb stage two map. The only way I would keep the car from doing this was flat foot shifting. I talked to my tuner and during my pro tune he tuned this problem out. Happy gear bangin!

01-02-2008, 03:06 PM	#10
jermdeez Spec C Club Posts: 1,604 Join Date: Feb 2005 Trader Rating: (1)	Re: Car Bucks When Shifting. If its acting like its hitting a rev limiter could be flat foot shifting. If it didn't do it before the tune could be a ****ty tune.

04-06-2006, 07:54 PM	#2
jays05 Spec C Club Fav Mod: when it's not blown up Location: Upstate NY Posts: 1,483 Join Date: Nov 2004 Trader Rating: (0)	Have you replaced any other driveline bushings? The Kartboy rear subframe outrigger bushings and TiC rear diff mount bushings tightened up the driveline in my car a lot.

04-06-2006, 07:59 PM	#3
JoeH Junior STI Driver Posts: 93 Join Date: Nov 2005 Trader Rating: (1)	no not yet, im getting those rear diff bushings put in next week. i havent got the outrigger ones yet. but whats weird is.. i used to be able to drive my car good, no bucking shifts at all clean smooth precise shifts so im not sure if its driver error. maybe i just started tryin to go to quick with my foot off the clutch in shifts ...im not sure...

04-06-2006, 08:49 PM	#5
JoeH Junior STI Driver Posts: 93 Join Date: Nov 2005 Trader Rating: (1)	i guess ill have to give it more practice and concentration. but it just seems weird to never bucking to now it bucks 75% of the time.

04-07-2006, 06:43 PM	#6
JoeH Junior STI Driver Posts: 93 Join Date: Nov 2005 Trader Rating: (1)	I just bought the valvoline 75w90 gear oil and some motul rear lsd diff fluid. Im a little behind i dont think its ever been changed and im at 44k.... Damn i hope everything is ok in there.

01-03-2008, 06:18 AM	#12
bzbuzz STI Driver Car: 06 WRX protuned stag Fav Mod: protune Location: IL Posts: 223 Join Date: Dec 2006 Trader Rating: (1)	Re: Car Bucks When Shifting. yeh my buckin issue sounds and acts exactly like when there is fuel-cut...but the thing is tho that it started happening when I tried kartboy pitchstop mount...that's when it started..so i replaced it w/ stock one back.. but still remains from time to time... i have lot of bushing and stuff...i checked the bolts for grp n engine mount that i can check under the car...all seemed fine..but when the weather gets better here i want to check the two nuts that connect the bushing and metal plate..that mite be loose now.. i dunno...i reinstalled grp n tranny mount just in case....the problem is still there..

01-03-2008, 09:34 AM	#13
V8Huntr Spec C Club Car: 04' WRB STi Fav Mod: TBE Location: Allentown, PA Posts: 1,516 Join Date: Sep 2006 Trader Rating: (0)	Re: Car Bucks When Shifting. If there are any other STi owners in your area let them drive your car to rule out improper driving technique. But it sound like you may be dumping fuel between shifts. You don't have a BOV do you?

01-03-2008, 09:57 AM	#15
La Mer NIИja Car: 2006 STI (SGM) Location: US - Southern California Posts: 38,089 Join Date: Jan 2006 Trader Rating: (5)	Re: Car Bucks When Shifting. This is pretty tough to diagnose over the internet. It could be a few things: Drivetrain, Engine, or ECM. It might be worth the drive to your tuner since tuners are usually in a shop capable of diagnosing all three areas of your car. This ad is not endorsed by this member. Please register or login to hide this ad.