Bucking bronco upon acceleration

[abq sfr]

This has only happened to me once, last weekend. I was at a yield sign, slowed to about 5 mph, and accelerated probably at 30-40% go pedal when the car started bucking like a bronco, like the power was cutting in and out every 1/4 second. Within a second or 2 I released the go pedal and tapped the brakes and it stopped. Never got any warnings on the dash. I'm not sure how warmed up the car was, I had driven it a long way about an hour before, and was around 2 miles from home when it happened. I hope it doesn't happen again, anybody ever experience something similar???

[galaxee]

my first thought from memory is to check the spark plugs. DH should be home within the hour, he'll know more than i do.

[oxnardprof]

<div class='quotetop'>QUOTE(abq sfr @ Sep 25 2007, 02:39 PM) [snapback]517529[/snapback]</div>

This has only happened to me once, last weekend. I was at a yield sign, slowed to about 5 mph, and accelerated probably at 30-40% go pedal when the car started bucking like a bronco, like the power was cutting in and out every 1/4 second. Within a second or 2 I released the go pedal and tapped the brakes and it stopped. Never got any warnings on the dash. I'm not sure how warmed up the car was, I had driven it a long way about an hour before, and was around 2 miles from home when it happened. I hope it doesn't happen again, anybody ever experience something similar???
[/b]

Could it be the anti-skid system? I notice a hesitation if I am turning right onto a busy street, and accelerate too rapidly - the car sort of hesitates or shudders.

[galaxee]

sounds like traction control, really, but if there were no lights...

if it were ABS, you'd hear it.

spark plugs, MAF sensor, etc would set a code. misfires would set a code immediately.

if it were the steering angle sensor it wouldn't apply anti-skid until you hit 9 mph.

any chance you could have set off the traction control? that puts you in a panic situation and maybe you missed the TC light? just speculating here.

[qbee42]

Traction control is also my guess. The light can flicker on and off pretty fast.

Tom

[abq sfr]

<div class='quotetop'>QUOTE(qbee42 @ Sep 25 2007, 06:07 PM) [snapback]517669[/snapback]</div>

Traction control is also my guess. The light can flicker on and off pretty fast.

Tom
[/b]

Traction control never even crossed my mind since I go through there every weekday morning without it happening, the road is level homogeneous pavement and never wet, and I was not accelerating hard. It is a very gradual right turn though. If that's what happens when TC randomly kicks in, they better do a recall. Car only has around 6000 miles.

[Hobbs]

I had a problem like that in a VW Sirocco years ago.

It was because of the resistance in the go pedal. I would press go. The acceleration of the car would mean I was applying less pressure on the go pedal. This inturn slowed the car accelerating at which point the tension in my ankle, or whatever would then apply more pressure on the accelerator again. (A bit like a negative feedback loop)

This happened a few times in that car but never on the 4 or 5 I have had since.

[richard schumacher]

Loose gravel, certain kinds of lane striping, and oil can also cause the anti-skid to kick in.

[donee]

<div class='quotetop'>QUOTE(Hobbs @ Sep 26 2007, 11:54 AM) [snapback]517868[/snapback]</div>

I had a problem like that in a VW Sirocco years ago.

It was because of the resistance in the go pedal. I would press go. The acceleration of the car would mean I was applying less pressure on the go pedal. This inturn slowed the car accelerating at which point the tension in my ankle, or whatever would then apply more pressure on the accelerator again. (A bit like a negative feedback loop)

This happened a few times in that car but never on the 4 or 5 I have had since.
[/b]

Actually a positive feedback loop. Positive feedback reinforces an oscillation, negative damps it.

<div class='quotetop'>QUOTE(abq sfr @ Sep 26 2007, 11:39 AM) [snapback]517861[/snapback]</div>

Traction control never even crossed my mind since I go through there every weekday morning without it happening, the road is level homogeneous pavement and never wet, and I was not accelerating hard. It is a very gradual right turn though. If that's what happens when TC randomly kicks in, they better do a recall. Car only has around 6000 miles.
[/b]

Hi Abq sfr,

The Prius has allot more torque at really low speeds. A patch of oil, that is worn away the next day could do it. There really is nothing random to the TC, other than the road you are on, unless there is a defect somewhere.

My SL2 had a cracked hub which caused the TC to brake very jittery. At least that is what they told me when they fixed it under waranty.

[donee]

<div class='quotetop'>QUOTE(richard schumacher @ Sep 29 2007, 12:02 PM) [snapback]519011[/snapback]</div>

Loose gravel, certain kinds of lane striping, and oil can also cause the anti-skid to kick in.
[/b]

Some other PC posters have had an issue with the VSC when turning in. I think it has to do with the chasis stiffness issue. The chassis flexes because its made with high strength (springy) metal. The flex is detected by the VSC yaw sensor, which then gets into an oscillatory response with the car. Before I put on a BT Tech plate, turning in over a reverse camber surface would cause an understeer. I do not have VSC, but any yaw sensor (human or otherwise) would sense that easily. The car did not come out of understeer until it was well down in speed - 15 mph or so. So, VSC would be oscillating all the way down to 15 mph.