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Discussion Starter #1
I have recently bought my 01 RS, recently i have noticed an unusual symptom regarding my car. During my low speeds such as in parking lots when i let go of the throttle, the car would jerk back and forth. It feels like there is not enough gas while i just let car ride.

My Idle speeds when stopped is perfectly fine, there is no shaking or anything. This only happens during 1st 2nd and 3rd gear and only happens when i let go of the throttle.

I have read a few posts about it, but nobody has provided an answer or where I should look.

anybody has this same problem?
 

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01 rsti CFblue, 06 sti PSM
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I have recently bought my 01 RS, recently i have noticed an unusual symptom regarding my car. During my low speeds such as in parking lots when i let go of the throttle, the car would jerk back and forth. It feels like there is not enough gas while i just let car ride.

My Idle speeds when stopped is perfectly fine, there is no shaking or anything. This only happens during 1st 2nd and 3rd gear and only happens when i let go of the throttle.

I have read a few posts about it, but nobody has provided an answer or where I should look.

anybody has this same problem?
(My Idle speeds when stopped when stopped is perfectly fine)your quote, i dont understand? what do you mean by that?

How many miles? any check engine light on? check your fuel regulator or fuel filter maybe bad.
 

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Discussion Starter #3
almost 140k, no check engine lights. When the car is in idle, it sits normally and doesn't shake but only jerks when in low speeds such as driving through a parking lot at 5 mphs.
I may look into replacing a fuel filter
 

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R56 Cooper S
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It's pretty much normal for these cars. My car does that, and has done it since the first day I've ever owned it, ant continues to do it now after my swap and upgraded mounts/bushings.

I think that the jerking is usually attributed to slop in the drivetrain. Thanks to the soft-as-mush bushings and mounts used in the car, when you let off the gas the engine, tranny, and differential go flopping all over the place.

I've got Group-N engine and tranny mounts, upgraded tranny cradle bushings, differential lockdown bolts, and outrigger bushings...and my car still does that. Aside from the pitch mount the last piece of the puzzle is the actual differential-to-subframe mount bushings, which on my car are like, super loose.

I'm fully convinced that once I either upgrade those bushings or get a brace for them, my jerking will stop. I haven't gotten around to it yet though, so my theory has yet to be tested.
 

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01 GC6 AW
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I guess this is normal cause it happens to my car to (since day 1). Usually on the low rpm range <1500, but it is only small jerks... Also running on Group N engine and tranny mounts.
 

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R56 Cooper S
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To OP:
Do you know if your car has upgraded (Group-N) engine or transmission mounts?

The reason I ask is that my car had them since I first bought it; I think the previous owner installed them. My car has also jerked really badly since I first bought it.

I have a buddy that has a 1996 wagon that does not have upgraded mounts. I drove his car, and while I could still slightly feel the jerkiness, it was SUPER subdued and hardly noticeable.

So based on that observation, I feel it's entirely feasible that upgrading just the engine/transmission mounts can lead to a more noticeable and pronounced jerking in low gears.
 

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2001 2.5 RS
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This I believe could also happen if the clutch dampeners are bad. Or would that just cause jerky gear changes?


Sent from my iPod touch using Tapatalk
 

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R56 Cooper S
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This I believe could also happen if the clutch dampeners are bad. Or would that just cause jerky gear changes?


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I imagine that would just affect gear changes, since when you're cruising in gear the clutch disc is already clamped down.

This issue is more when you're already in gear and you just let off or press on the gas at low speeds.

Shoot, my car will even do it in 3rd.
 

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99 rs coupe, black
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I too can Now feel the jerking at low rpms in low gears. but my question is how many of you with this issue have intakes on the car? I never noticed this jerking until i put on my short ram intake and now i notice Big time... im thinking something to do with the amount of air getting to the throttle body in a differant way then, when the car has a tourqe box on it which the subi engineers probably put for a reason. tell me what you guys think....
 

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R56 Cooper S
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I have never had an aftermarket intake on my car, and I have had this problem.

I'm fairly certain at this point that this problem is mostly just related to the inherent slop in the driveline of these cars. The small amount of space between the teeth of the gears in the transmission, the differential, the small amount of play in the driveshaft joints...it all adds up to what feels like a lot of play/jerkiness when the load on the drivetrain is suddenly released.

I say this after upgrading darn near every drivetrain related bushing there is (except the pitch stop), and nothing has helped.
 

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99 rs coupe, black
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danm what a bummer. well dont get an intake. i never noticed it until i put my intake on and now i notice big time, if it is all the drivetrain gear fitment then that sucks, becuz im sure that a lot of stress of gear teeth constantly changing direction of load..............scary!
 

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1999 Impreza RS Coupe - Blue
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I have experienced jerkyness on liftoff too. I think a bit of harshness is common in these cars, but i have experienced REALLY bad jerkyness. I determined that my TPS was not properly adjusted to reach 0% throttle on liftoff. I'm assuming the issue was due to the IACV not opening properly on throttle release, partially stalling the engine and causing the jerkyness.
 

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1999 Impreza RS Coupe - Blue
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how did you fix it? or did you
I have a bluetooth OBD connector and the Torque app on my phone. I used the app to get the throttle position from the ecu (in %). The service manual says to get the voltage from the ECU to determine the TPS position, but I couldn't find the right pins. The OBD method worked for me though. Process is as follows:

1. Connect OBD connector
2. Look at throttle position reading - with your foot off the gas it should show 0%, and with the pedal to the metal it should be 100%. If not, then the TPS needs to be adjusted.

To adjust TPS:
1. loosen two screws mounting the TPS.
2. While watching the throttle position, use your hand to turn the butterfly valve on the throttle. Move the TPS around until it operates properly.
3. Tighten the screws on the TPS.
4. Check again from inside the car to ensure that it still operates as expected.


Hope this helps!
 

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13 Years of RS
2005 Toyota Corolla :(
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how did you fix it? or did you
Got a car that wasn't a Subaru, lol! You lug the engine (5 mph in 3rd gear will do the trick!), you're going to make it unhappy, and it will let you know. It's just the nature of the beast.
 

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2005 Impreza 2.5RS Black
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i have the exact same problem with my 05 RS. Although it doesn't matter what gear im in or what speed as soon as i let off the gas (quickly or slowly) the whole car will jerk for a second or 2. And sometimes when i give it gas too. I have installed an aftermarket cold air intake but im almost positive that my car has done that even before that.
 
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