Car rocking back and forth

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
lilshortwun
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Car rocking back and forth

Post by lilshortwun »

Hello I have a 2006 acura rsx type s and I think my car has some problems although it could be driver error. Never drove a diff manual car before so I wouldn't know what's normal and what's not. Most of the problems come from a situation where I am slowing down to a crawl and having to accelerate again before I stop completely. For example, it's a red light so I put it in neutral and coast to a stop. I am slowing down and reach ~5 mph when the light turns green. Rpm seems to be stuck around 2-2.5k because I haven't stopped completely yet. I put it into 2nd gear and since rpm is kinda high, I roll out the clutch. As soon as it reaches the engagement point, my car starts jerking back and forth and doesn't stop until I'm ready to shift to 3rd. Now at this point i figured maybe the rpm's were too low. The next time that happened, I raised the rpm's to 3k before letting the clutch out. It still jerks a little bit, and when I fully let it out, I depress the throttle and it jerks for a second before going smoothly. Maybe I am just going about it wrong. Should I keep my foot on the accelerator while letting the clutch out? Another problem I have which I think is related is that if I leave my car in gear while going over a speedbump slowing down to a speed just before stalling and let the car pull itself over, car starts bucking like crazy unless I press the clutch in. Also, when I am driving in parking lots, I am usually in 1st or 2nd. Usually I am in 1st around 2800-3k rpm. If I let off the throttle, car will start engine braking but it's not smooth engine braking. It sounds like it's engine braking then it stops jerks a little bit, brakes some more and jerks again. Sorry for the long post but I just wanted to describe in detail what my car is doing. Any help is appreciated thanks.
Last edited by lilshortwun on Wed Sep 15, 2010 12:13 am, edited 2 times in total.
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theholycow
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Re: Jerking Problem

Post by theholycow »

lilshortwun wrote:I put it in neutral and coast to a stop. I am slowing down and reach ~5 mph when the light turns green. Rpm seems to be stuck around 2-2.5k because I haven't stopped completely yet.
In neutral with your foot off the accelerator it's over 2000 RPM? How long have you been in neutral with your foot off the accelerator, by that time?
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94Corolla5Speed
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Re: Jerking Problem

Post by 94Corolla5Speed »

Hehehehehehe...he said jerking problem.
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4onthefloor
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Re: Jerking Problem

Post by 4onthefloor »

Wait.....your name is lilshortwun and you have a jerking problem?!?! That's too good. I'm sorry that's something you have to work out on your own.......behind closed doors.
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Re: Car jerking

Post by lilshortwun »

Uh hello thanks for joining but I do not see "jerking problem" anywhere.

Anyway, I will usually be in cruising in 5th, i'll slow down a bit maybe to around 30mph before putting it into neutral. The rpm's stay around 2k until I stop which it then goes to idle. I'd say I was in neutral for 100-200 ft. or normal stopping distance.
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gizmo
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Re: Car jerking

Post by gizmo »

Once you've engaged neutral, your engine should idle almost immediately. Is that the case with your car?

Jerking back and forth might be normal. Rather than explaining all the possible cases where it's both normal and abnormal, I'll just ask you this: if you accelerate through second gear to your shift point, instead of shifting, what happens when you remain in gear and slow the car to idle? does it still rock back and forth near idle?

Also, are you the first owner of the car? Is the car new? How many miles are on the clutch? etc.
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Re: Car jerking

Post by 94Corolla5Speed »

You fail at ninja editing OP :lol:
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Re: Car jerking

Post by FDSpirit »

:lol: . Oh dear.....
4onthefloor wrote:Wait.....your name is lilshortwun and you have a jerking problem?!?! That's too good. I'm sorry that's something you have to work out on your own.......behind closed doors.
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lilshortwun
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Re: Car jerking

Post by lilshortwun »

gizmo wrote:Once you've engaged neutral, your engine should idle almost immediately. Is that the case with your car?

Jerking back and forth might be normal. Rather than explaining all the possible cases where it's both normal and abnormal, I'll just ask you this: if you accelerate through second gear to your shift point, instead of shifting, what happens when you remain in gear and slow the car to idle? does it still rock back and forth near idle?

Also, are you the first owner of the car? Is the car new? How many miles are on the clutch? etc.
Is that so? Let's say I was cruising at 3k rpm and I shifted to neutral. It would stay at 3k and drop to idle when I stop. If I'm in 2nd gear and I slow it to idle, it will start rocking more intensely as rpm's drop. This usually only happens at low speeds though. I don't realy experience it when I'm cruising in 5th and slow near idle. I am the third owner. It was involved in a front end accident when I bought it. My dad is a mechanic and he said the engine checked out fine. Oh yeah, it has almost 60k miles. I don't think the clutch has ever been replaced and it doesnt feel like it needs to either.
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Re: Car rocking back and forth

Post by gizmo »

I've never heard of a car that, when shifted to neutral, doesn't immediately fall toward idle but that doesn't mean that there's anything wrong with your car -- it just means I've never heard of a car that does what yours does.

At low speeds in second gear, if I coast in my car, it will rock back and forth if I don't modulate the gas pedal. It's probably just how your car is geared. You'll probably notice you can cure the rocking, if you gently apply the gas pedal at low speeds. It's not unusual for a car to rock at low speeds in low gear, although you'll hear most rookies complain about it in 1st gear -- does the same sort of thing happen in first, just more pronounced?

Lastly, as an aside, you shouldn't have to feed power through the clutch at 3K. If you're afraid it won't sync up quickly enough, just engage the clutch slower, don't feed power through it. You shouldn't be accelerating through a slipping clutch beyond 1.5KRPM.
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Re: Car rocking back and forth

Post by lilshortwun »

thanks for the advice. I actually tried feeding power one time, and it was not pretty on the clutch. hopefully someone can help me with the idle situation.

Edit: I actually read somewhere a while ago that low torque causes jerking at low speeds. Any validity to this? My car has really low torque
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Re: Car rocking back and forth

Post by FDSpirit »

Lol. Yeah. You need to be more gentle with the throttle in lower gears. Getting throttle manipulation down after driving an auto for so long is still an issue with me. Nowhere near as bad as when I started, but I still sometimes put too much pressure on the gas pedal.
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Re: Car rocking back and forth

Post by theholycow »

^For getting gentle on the throttle: If you use only the corner of the pedal with your toe, try your whole foot. If you use your whole foot, try using only the corner of the pedal with your toe.

Also do some practice exercises in the driveway in neutral, seeing if you can rev to various RPM levels accurately.
lilshortwun wrote:cruising at 3k rpm and I shifted to neutral. It would stay at 3k and drop to idle when I stop.
Do some testing. Drive at 3000 RPM and shift to neutral on an empty road and do not use the brakes, just coast. See how long, as in time (not distance), it continues at 3000 RPM. I'm interested in how many seconds it stays that way.
gizmo wrote:I've never heard of a car that, when shifted to neutral, doesn't immediately fall toward idle
You haven't? I thought tC's have rev hang. My VW sure has it.

Does anyone here know if lilshortwun's 2006 RSX-s would have rev hang?

When it does have rev hang, you should not step on the accelerator while engaging the clutch, since the computer is already doing it for you. (That is, unless you actually need more RPM for the gear you've chosen.)
lilshortwun wrote:Edit: I actually read somewhere a while ago that low torque causes jerking at low speeds. Any validity to this? My car has really low torque
Low torque at low RPM can cause something that you might describe as jerking. Also, high torque can. And very low gears regardless of RPM.

Have you tried choosing a different gear for less or more RPM?

I think you need someone else who has driven a stick shift to drive your car and say if it's working right or not. Do you know anyone? Where are you located, maybe someone on the forum is nearby.
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Re: Car rocking back and forth

Post by gizmo »

my car doesn't really have rev hang. and if you turn the ac on, there words rev hang don't even come to mind.

...anyone who shifts into neutral and rolls for 200 ft at 3KRPM seems to me like they have a unique car that has rev hanged-to-death, no?
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Re: Car rocking back and forth

Post by theholycow »

No, that's a tiny amount of rev hang by my standards.

The most severe rev hang I had was at 5000RPM for at least a half mile. For a difficult pass I took 3rd to 5000RPM then put it in neutral. Then I decided that rather than braking down to the speed limit I'd coast. Engine speed stayed steady at 5000RPM even as the car gradually slowed. Eventually I think I put it in 5th just to stop the rev hang.
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