Technical GP - Mind of its own and fuel issue??

[claire bear]

Hey everyone!

I have an 09 GP 1.4 Active and its got into driving on its own! I noticed it when pulling away, I can go from 1st to 2nd but it gets to about 1100rpm and it feels like something engages and off I go! I can take my foot off the accelerator and its driving on its own. Also can put my foot on the brake to slow down (no foot on clutch) and it slows, take your foot off the brake and away it goes, still no food on the accelerator. I have had it also when slowing down to turn into a road then suddenly I get a surge of power and its off, its sometimes so quick, you dont have time to turn the steering wheel so if there was someone on the other side of the road, I would run into them!

Also filled up my car to the brim with fuel, drove 8 miles home and it was reading between full and 3/4. Checked I have filled up on a flat surface and been to different garages and it drops loads after a short journey. Has had several times.

Has anyone else experienced this and can shed some light on it? Taking it into the dealer soon but just wanted to see if its a common fault first before wasting peoples' time.

Any help would be gratefully appreciated.

Thanks

Claire

 

[ghsaunders40]

Take it to the dealer. They wont think your waisting time!

I had an old fiesta that did it. Turned out to be faulty fuel injectors.

 

[T14086]

Take it to the dealer. They wont think your waisting time!

exactly & its under warranty

 

[ducasi]

Unexpected power at low revs can be due to the engine management system trying to avoid stalling by opening up the throttle a bit.

I've also had a strange sudden drops of fuel-gauge level shortly after filling up – only once though. No idea what caused it.

 

[GP1416valver]

isnt their a recall on the intake manifold ??

 

[Dan89]

Used to happen on my old works Focus TD, just assumed it was to avoid the chugg chugg at low revs in a diesel.

 

[James1989]

ive had that before ive got up a hill to a junction let of the accelerator and it pulls itself up the hill until i stop it it can do it in 2nd and 3rd on quite damn steep inclines,

i just assumed its because of the turbo in me tjet the torque just had the power to didnt realise it can be problematic?

 

[T14086]

Used to happen on my old works Focus TD, just assumed it was to avoid the chugg chugg at low revs in a diesel.

were talking about a 1.4 petrol though

 

[Dan89]

were talking about a 1.4 petrol though

Yep but it's the same phenomenon, probably caused by anti stall...

My point was I don't think it's a problem as such.

 

[T14086]

The OP's description sounds too 'severe' for a petrol engine.

I can go up to 5th gear in my diesel without touching the throttle

 

[Dan89]

It's alright for some

Then again these days with drive by wire throttles etc things can go funny in ways you might not expect, so it should always be checked out properly

 

[T14086]

good thing about 'fly by wire' is that it has a back up (2 tracks) so car would go into 'limp home mode'

 

[Dan89]

I just had a scan through some of my x-by-wire notes and it appears a dodgy throttle position sensor can cause surging like what is happening to these cars. I also found something I wrote on management systems and electronics, this is a relevant bit if anyone's inteerested.

In the modern vehicle it is common to see a throttle position sensor to give feedback to various other systems such as the traction control or antilock braking system. However, there still exists a mechanical Bowden cable which actuates the throttle body. In a vehicle with full electronic throttle control or throttle-by-wire the throttle is equipped with an electronic actuator which is controlled by an electronic control unit or ECU. The ECU calculates the data from the throttle position, engine speed, vehicle speed and other sensors and determines the required throttle position by means of a closed-loop algorithm. This total control of the throttle position by an electronic system can be criticised as taking away the actual control from the driver. However, it is often not realised that the most engineering in a system such as throttle-by-wire is placed in the failure and fault management of the various components. As various methods are employed such as sensor and controller redundancy to ensure the safety of the throttle-by-wire system it is unfair to conclude that in this instance removing the mechanical linkages between driver and vehicle can be considered a safety risk. In fact there are many advantages to a management system such as throttle-by-wire, however most are only found when the system is implemented on a vehicle which is equipped with other electronic management systems such as cruise control or traction control. On a vehicle equipped with cruise control to maintain the vehicle’s set speed the throttle is actuated by a solenoid or servomechanism attached to the conventional throttle cable. If a vehicle incorporates both throttle-by-wire and cruise control the vehicle speed can be maintained by the throttle-by-wire system alone, removing the mechanical actuating mechanism. This can lead to increased reliability as only the electronic actuator in the throttle and the electronic control system itself is available to fail, with both being typically more reliable than a mechanical based actuating system.