[QUOTE]Originally posted by hpalmer
[B]

Maybe it is a map sensor issue but bucking due to low gear low rpm is common on a lot of manual transmission cars.

 

Thanks all, this is really informative. I thought it might be related to the MAP sensor and had done a search on it before I started the thread, but just to be safe I thought I would ask.

Mike

 

Not sure if Hugh owns or has driven the S2k in hot weather in heavy traffic, but just about all of us in Houston have experienced it at one time or another. Being an old guy and haven driven stick shifts since 1957, I would say the problem is pretty much unique to this car. Small price to pay to figure out how to cope with it for the rest of the pleasure it brings.

 

Hello, to you fellow s2000er's!

This is my first visit to this cool site and my first post.

2002
blk/blk

I to have experienced this phenom of the bucking the s2000 goes through. all of the posts that are stated are very similar to mine, as I was in bumper to bumper traffic in first gear, moving very slow if moving at all, as I was in first gear i went to accelerate and buck buck buck....I honestly thought someone was bumping me from behind as the vehicle shook, I was thinking ...geeezzz I spent all this money and I don't even know how to drive, but now I see that others have experienced the same.

At any rate I have read the responses and in detail to what might cause this and appreciate the in depth knowledge that some of you possess about the automotive technology.

 

Couldn't have said it better myself.

 

This "bucking" issue has been brought up even from the early history of this car. I don't believe that it can be considered a problem that is endemic in nature (automotively speaking). I contend that it is rather a function of driving technique combined with the specified conditions of slow speed, stop & go types of driving.
When the car is being driven at about 5 mph (or 8 kph), in stop & go traffic (assuming the engine has long since reached operating temps), the engine is running at or very near its idle speed. Under these conditions, you are asking the engine to both "idle" and "motivate" the car at a steady speed at the same time. This is all fine and good until you suddenly and "harshly" place "load" on the motor and ask it to propel all that mass to a higher speed. By "throttling" up in this manner, the computer senses the increase in air, the change in manifold pressure and tries to dump more fuel into the intake and advance the timing to give you what you want. The engine just can't do it under these low speed, low torque conditions. It doesn't have enough torque to suddenly move this mass faster and wants to die, yet the car has just enough forward momentum to prevent it from dying. This situation is probably the most horrendous "lugging" scenario you can do to the car. It's bad enough to lug the car at higher speeds in a higher gear but in this set of conditions, the car (and its engine) has much more inertia going for it to help to get past the lugging to where the rpm is sufficiently high enough where the torque can compensate for the mass it is asked to move. This is not the case when the engine is at near idle and the car's speed is very low. Imagine yourself peddling a "loaded" excercise bike very slowly. When someone fires a starting pistol, you must suddenly put a whole lot of strength to try and get the loaded wheel to spin faster. It is very hard and you might even "pull" something but unlike the car, your body has the ability to tell you to "back off" (pain). The car tries to do what you tell it to and has no way to "back off" unless you change something (letting off the gas).
When driving in such slow conditions like slow traffic or manouvering in a crowded parking lot, you should be doing more clutch work - slipping the clutch with the application of gas just enough to propel the car sufficiently to keep up with traffic or to maintain that low speed. Then push in the clutch and use the car's momentum to coast for next bit of distance until you need more momentum when you would do the clutch/gas thing again. Using this technique, your car's bucking should be eliminated and at the very least, be alleviated. When it's time to "take off" once the traffic clears ahead of you, you should be doing so as if you were moving off from a stop by using your clutch. You need some increased rpm's to develop the torque that is necessary to get this mass going. By using the clutch, you give the engine the chance to get that extra bit of torque required and you also introduce that mass gradually. In an automatic transmission, the torque converter does this for you.
Sure, you say that you've been driving stick for years and this is the first car that does this. Each model of car may require a slightly different set of parameters to duplicate this bucking but I can assure you that even on V8 and V10 cars, it can be done. These "parameters" may include things like the degree and rate of throttle opening, engine's normal idle speed, its normal "rev range", road speed, how much fuel its computer tells it to dump in, how much advance to dial in and a whole bunch of other stuff I can't think of right now. I've made Vettes and a Viper "buck". I wanted to see if a huge torque monster could be made to NOT cope with sudden and severe low speed "torque loading" and it can. But once you know how to do it and why it does it you can use a different driving technique to overcome it.
Happy clutch control!
(This is my story and I'm sticking to it! )

 

I've experienced this "bucking" in my Prelude as well...usually when I'm on/past speed bumps and not paying attention. But hasn't experienced any yet in my S...partly I think because S is much less prone to "bucking" (i.e. I can just put a gentle pressure on my gas pedal with my left foot completely off the clutch even at 1st gear). With my Prelude I had to be very "gentle and steady" on my gas in order to avoid "bucking" at 1st...ended up just upshifting to 2nd.

Don't think it's necessarily a bad thing...just another Honda characteristics you have to live with. But no problem if you are paying attention to your feet instead of looking at a hot chic coming out of a mall .

 

phew!..thought it was just me!..either that or i'm a bad driver..not!..

 

im always in 2nd in traffic....if i come to a stop, i shift to first, get the car rolling, then shift to 2nd
always works for me
Xvipers story is also true

 

It sounds like you have modified quite a few parts of your car. Your car could be doing what it does for a mulitude of reasons. You may be suffering from a "lazy" MAP sensor and the engine is getting too much air and not enough fuel to rev up. All your mods may not be in harmony with one another. For you, it might be wise to get it diagnosed and tuned.