We have recently bought a 2005 S2000i 16K miles on the clock.
The car hesitates and sometimes kangeroos as you pull away from rest.
We have taken it back to the dealer who found there was " nothing wrong".
When my wife collected it exhibited the problem as she left the dealer - she took it straight back and fortunately demonstrated the problem to the service manager.
They kept it for another 2 days but still say they can't find anything wrong but have made some "adjustments". Suggested it was my wife's driving!
Anybody out there had this kind of problem? I think it must be an ECU or set up problem.
Grateful any feedback on this before we go back again.

 

Umm.. What do you mean when it "kangeroos" never heard of this term?

 

Mine did this when I was new to driving stick, I think it might be her driving, it use to do that when I engaged the clutch too slow.

 

kangaroos thats a new one

 

The term "Kangaroo" has been used many times in the past to describe the bucking action that happens, usually when you're creeping at slow speeds in first gear with a hot engine, then try to accelerate.

Although this is often attributed to "heat bog" and the unrealized back-and-forth motion of your body weight to the gas pedal, you might have a different problem because this usually doesn't happen when pulling away from a complete stop.

If you have heat bog, this causes your engine to dip in speed slightly when you try to accelerate. As a result, your body momentum pushes the pedal slightly forward. Then when the engine finally does accelerate, it pushes you back in your seat, slightly releasing your foot on the gas pedal. That in turn causes the engine to "kangaroo" again, and it continues until you take your foot off the gas or press the clutch.

One way to get around it is to cram your foot against the carpet next to the gas pedal and use this as a "lever" to slightly change force on the gas pedal. This will prevent the inadvertant back-and-forth motion of your body momentum from being transferred to the gas pedal.

 

I've never been a fan of the "foot hitting the pedal" theory (I usually drive with my right heel anchored against the carpet) nor the heat bog theory when it came to the bucking issue, even though a lot of vets seem to swear by it, but that's just me. Personally, I think it's the driving.

When I first got the car, the bucking would happen if I let out the clutch all the way too quickly at low RPMs, and then tried to gas it hard. I've adjusted my style, and it doesn't happen anymore, yet I can still duplicate it on command. That would seem to eliminate heat as an issue, especially when I could do it during the winter, too. At least, I thought so, I haven't bothered to duplicate it lately because that would just be retarded.

But I'm completely aware that I'm just a noob, and I haven't done formal testing. And there are probably plenty of gearheads here who can give you a better idea.

 

You might try checking the slack in the throttle cable. If it's too loose, that aggravates the problem described. But ultimately the problem is usually caused by the driver, as slalom44 described.

 

Thanks for the input - But I can't agree that it is the driver - It does it when I drive the car as well. My car is a 200hp Seat Leon MKII and if was driving style then this would show up on this vehicle as well. My wife has also had an Elise with no problems like this. Its worse when its cold.
We are going to request a drive in the dealers S2000 demonstrator which should eliminate the driving style issue.
I'll post the solution when we have it.

 

If it's worse when it's cold, then it is unlikely the same problem. Heat bog is worst when it's hot outside with a hot engine.

But if your problem is caused by a hesitation when blipping the accelerator, consider wedging your foot against the carpet and see if it eliminates the kangarooing. I can't tell you how many people have said that their problem was not driver input because they don't have the problem with any other car (and they know how to drive a car). The way you sit in an S2000, and its stiff suspension makes this problem happen.

 

Iv'e been chasing down an intermittent stumble/hesitation for awhile. The car never threw a code, but would occasionally hesitate around 3K- 4K rpms. I can see the AFR go lean when it does it. I checked all the sensors, but all were good. Seemed like the secondary air system was the culprit since I noticed that occasionally I would also get this sudden and massive compression braking on deceleration (secondary air injection also operates on decel). I checked everything: pump, relay, current sensor, vac. cannister, both valves, hoses, wiring, ECM - all checked out fine. Finally I decided that either the vac operated diaphram valve (which is at the back of the intake mainfold) or the vac solenoid valve (which controls the vac. diaphram valve) must be getting sticky. Turns out its the vac solenoid valve, even though it checked out fine per Helm's and on the bench with a 12V power supply.

Here's an easy way to see if the vac solenoid valve is causing hesitiation/stumbling problems: disconnect the vac line that goes to the diaphram valve and disconnect the air supply line at the diaphram valve also. This will will effectively stop the secondary air from entering the exhaust manifold and will keep the exhaust system sealed at the diaphram valve. The secondary air system will still operate, but the air will just blow out under the hood. Take a test drive and if the stumbling/hesitation goes away, then the vac solenoid valve is probably getting sticky.

What a hard one to solve without any DTCs, but the occasional hesitation issue is gone for good now.