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Tuning Car suddenly races forward

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Tuning Car suddenly races forward

S

Starbucks Junkie

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Don't know if anybody else has experienced this with thier car, but mine randomly races off from an almost starting position.

Sounds silly I know, but I can accelerate, but the car takes over and excessively speeds and I have to apply the break to stop and kind of reset the car..

It happens very randomly, but it has happened in the same spot a few times now, which makes me think it is something about the angle of the surface that the car is on.

Has anybody else experienced this, It's very hard to explain, and would be even harder to explain to a Garage, and pretty much impossible to replicate.
 
Sorry, should have specified, its a 2ltr Diesel Cross Manual and it only happens in first gear, it's almost like the Turbo engages when it has no reason to.
 
Last edited:
Starbucks Junkie said:
Sorry, should have specified, its a 2ltr Diesel Cross Manual and it only happens in first gear, it's almost like the Turbo engages when it has no reason to.
Click to expand...



What happens in Sport Mode with the Turbo Boost gauge on the screen in front of you?
 
varesecrazy said:
Hi.:)

That does sound odd.

Ok. Tell us more...


I am intrigued by the reference to
'Certain places'. ??

Charlie
Click to expand...

So when it happens it happens 99% of the time at the approach to a Roundabout, either from a slow rolling into acceleration or from a stop to acceleration, it has happened on the same roundabout a few times now, and this roundabout has a very slight gradient not that it's really noticeable.

My Partner drives the car too, and it happened to her as she was pulling away onto a different roundabout.
 
Eklipze3k said:
He's asking you to do it as a diagnostic aid, if you put it into Sport mode, when it does this surging thing you'll be able to see if the turbo is indeed boosting more than normal.
Click to expand...

This would mean I had to drive the car continuously in Sport Mode as i cannot guarantee when it's going to happen again.

It also happens so quickly that if I was to view the screen as and when it occurs again I might hit something as I have to break to stop the car from running away...

I was just wondering if anybody else has experienced this as I cannot be the only person.
 
Starbucks Junkie said:
This would mean I had to drive the car continuously in Sport Mode as i cannot guarantee when it's going to happen again.

It also happens so quickly that if I was to view the screen as and when it occurs again I might hit something as I have to break to stop the car from running away...

I was just wondering if anybody else has experienced this as I cannot be the only person.
Click to expand...

If you dip the clutch it will stop the vehicle accelleratiing :)
 
Last edited:
Starbucks Junkie said:
So when it happens it happens 99% of the time at the approach to a Roundabout, either from a slow rolling into acceleration or from a stop to acceleration, it has happened on the same roundabout a few times now, and this roundabout has a very slight gradient not that it's really noticeable.

My Partner drives the car too, and it happened to her as she was pulling away onto a different roundabout.
Click to expand...

So.. assuming this minor slope is UPHILL you are aiming to
Gently Gain Speed ;.( this doesnt occur on a 'neutral' throttle ')
 
varesecrazy said:
So.. assuming this minor slope is UPHILL you are aiming to
Gently Gain Speed ;.( this doesnt occur on a 'neutral' throttle ')
Click to expand...

I'm not sure what you are trying to say.

This issue occurs not from Neutral but when you are in 1st Gear and pulling away.
 
If it's getting ahead of itself while you're accelrating then it may be worth having the throttle position sensor cleaned, since it's just a potentiometer and it lives in the "soot and oil" world of the throttle body.

500X (not an expert on it) probably has a fly-by-wire throttle rather than a cable attached to the throttle, so it's the throttle sensor that tells the ECU how much throttle position you're using. That obviously has to be correct for you to get the amount of "gas" you're expecting. A duff reading could be telling the ECU that you want to accelerate very quickly rather than just briskly.


Ralf S.
 
Ralf S. said:
If it's getting ahead of itself while you're accelrating then it may be worth having the throttle position sensor cleaned, since it's just a potentiometer and it lives in the "soot and oil" world of the throttle body.

500X (not an expert on it) probably has a fly-by-wire throttle rather than a cable attached to the throttle, so it's the throttle sensor that tells the ECU how much throttle position you're using. That obviously has to be correct for you to get the amount of "gas" you're expecting. A duff reading could be telling the ECU that you want to accelerate very quickly rather than just briskly.


Ralf S.
Click to expand...

That all makes perfect sense, but surely if the reading was incorrect it would cause the car to accelerate in this manner every time, not intermittantly?
 
It may or may not be linked, but I also find on occasions and only when attempting acceleration on a Gradient in 4th or 5th Gear that when the Gas pedal is pressed, the car engine Rev's but doesnt actually accelerate.

To counter this, I have to take my foot off the Gas Pedal and then re-press it and it starts to accelerate.

Could the extreme acceleration from 1st Gear pull away and this none acceleration be linked?
 
Starbucks Junkie said:
That all makes perfect sense, but surely if the reading was incorrect it would cause the car to accelerate in this manner every time, not intermittantly?
Click to expand...

Good point... but you're being logical. This is car electronics we're talking about.. :D

The ECU gets a signal from several sensors and controls what the car does, so it's possible that it comes up with a different answer on different occasions. For example, if you are travelling at a different speed it can supply different amounts of fuel, even with the same throttle position depending on what is optimal or best for emissions etc.

I presume the car does this hot or cold and it's not engine temp' related which could be the engine cold-start setting (old style "choke") being too keen?


Ralf S.
 
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