S2000 Under The Hood S2000 Technical and Mechanical discussions.

car is lunging at low rpms?

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Old 08-30-2007, 09:04 PM
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Default car is lunging at low rpms?

I just moved to LA and when im in heavy traffic, which is pretty much all the time, my car has been lunging/jerking back and forth at low rpms. When im in slow moving traffic that barely allows me to be in first or second gear ( for example when im going like 7-10 mph and the tach is between 1 to 2k) When i go to speed up with moving traffic my car starts to lunge back and forth out of control!!! I must look to other drivers as if im flooring it then slamming the brakes over and over. Once it starts this i let off the gas but it still jerks back and forth quite a bit. The first couple times it happened i tried giving it a little more gas but that makes the jerking much worse. It has to be fuel related, like its just cutting out or getting spurts of fuel.

It rarely to never does this if i just take off from a dead stop and get up to speed. Only when im accelerating from really low rpms in first and second gear.


Can anyone help me!! whats wrong with my car?

P.S. sorry for the novel... i just wanted to explain in detail.

Old 08-30-2007, 09:17 PM
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Unfortunately...this is somewhat "normal". You can try changing your MAP sensor, but it will only help some.

Honestly, the best solution is to change your driving style. Don't let the rpms get that low...engage the clutch instead and coast.
Old 08-30-2007, 10:03 PM
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thanks for the post...i didnt know that was a common problem. Its getting pretty bad though. It used to lunge just a little be once and a while. Maybe ill try a new map sensor. Any one know a good place to get one? I appreciate the info.
thanks
Old 08-31-2007, 04:59 AM
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It's the slop in the driveline. For whatever reason Honda saw fit to give us quite a bit of play in the driveline and in certain situations it starts an oscillation that can only be stopped by disengaging the power application (push in the clutch)

Get under your car and twist your driveshaft (preferably while the car is not moving). You will be amazed at how far it will move. I have compared it a number of cars and it easily moves twice as far as any other car I've seen.
Old 08-31-2007, 06:07 AM
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it is normal and its happened to me a couple of times too. its from heatsoaking the engine and the MAP sensor is very sensitive to this. I found that an aftermarket CAI helps remedy the situation
Old 08-31-2007, 08:01 AM
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I was considering a CAI anyway. With a CAI does the car throw a CEL. I just spent so much time/money getting mine to stay off this past year that i dont want to see it anymore staring back at me from the dash.
Old 08-31-2007, 08:08 AM
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Originally Posted by negcamber,Aug 30 2007, 09:17 PM

Honestly, the best solution is to change your driving style. Don't let the rpms get that low...engage the clutch instead and coast.
ive tried to coast as much as i can, Its just soo much on and off the clutch. What i need is a new daily driver. Something automatic!!!
Old 08-31-2007, 08:56 AM
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Heatsoak FTW, Yup a cai will help, or a vented hood or both of that combo and no heatsoak(most times).
Old 08-31-2007, 09:09 AM
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Originally Posted by lude9285,Aug 31 2007, 12:08 PM
What i need is a new daily driver. Something automatic!!!
Wuss!
Old 08-31-2007, 09:58 AM
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It's driver error. I've posted this a dozen times. Don't blame the car.

When you press on the accelerator, the car lunges forward. That causes your body (and your right leg) to move backward, causing the car to buck. Your reflexes press on the pedal more, causing the cycle to start again.

You don't even know you're doing it. Heat soak aggrivates the situation, but the primary cause is that your entire leg is going forward and back, causing the car to buck. Remember: you're sitting very low in a car with a very stiff seat and suspension, so the slightest movement of your leg will transfer the force to the gas pedal.

Solution: Cram the right side of your right foot against the carpet to the right. Let the friction between the carpet and your foot prevent you from moving your foot on the gas pedal. When you want to move the gas pedal, put the force on the carpet as well, not just on the gas pedal.

You will be amazed that the problem disappears.


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