(T) serious over revving incident

Hi, just got my 2007 Doblo van and the other day it suddenly hit top revs, rev counter needle hit the top of the dial and the noise was incredible, I took my foot off accelerator; no difference, put it in neutral; no difference, turned off ignition key; it stopped...phew!
AA man didn't know what did it, I drove it to garage they don't either.checked threads here and similar problems like this seem to be with diesel turbos mine is petrol 1.4
Have driven it to work now and its ok, but it was very scary and would like to know why it did it.
hope someone can help....??

I would imagine the throttle pedal could be at fault.

They are fly by wire and not exempt from trouble.

It could be a dirty connection or some such, have it checked out.

Oh, another thought.....did you check that the rubber mat wasn't causing a problem?

Don't worry the engine management wouldn't have allowed it to over rev so no harm done.

No harm this time, but what if it does it plodding along the high street in 2nd gear, about to go into 3rd and it takes off and runs some poor sod over?

...or pulling away from lights/junction and it slams into the back of another vehicle?

I would be getting it checked out. It will need someone switched on with an oscilloscope to check for a fault in the throttle potentiometer

Our 2008 1.4 Doblo did exactly the same thing when we first had it. We were in busy traffic on a dual carriageway. Trouser accident time! I was convinced that the pedal was stuck under the mat but there was no way that could have happened.

Due to another issue the throttle body was recalibrated a few weeks later. It has not happened again but it was while before I 100% trusted it again.

Are we talking an Auto electrician here Andoo or main dealer diagnostics?
Is there anything that can be done to service the throttle sensor - cleaning contacts etc. or is it usually a replacement new part?

I doubt main dealers would have a scope, most small time Auto sparks don't even have them, just serious repair shops. You could try googling in your area and calling to ask.

Throttle pots and throttle bodies are almost always sealed for life. The contacts within the plug/sockets to them can leak past the silicone seal so a check for green muck (verdigris) build up is worth a look.

You can get contact/switch cleaner from Maplin or Halfords to clean the pins.

The throttle body is a stepper motor that receives a small current via the throttle pedal (potentiometer, a bit like a volume control on a radio). The harder you press it down, the more volts travel through to the throttle body, to move the motor and open the throttle. If for some reason, too much go through (short circuit from wet contact or such like, perhaps even radio interference) the throttle can open wide and VROOOOOOOM!!!!

Throttle pots do wear and can result in a flat spot, or a worn part, but normally after mega miles and normally they simply fail to rev. It could be a build fault or like I suggested, a short.

wow! thank you all for your help,
Will be ringing around to find someone who can do all the things you suggest.

Although It was running so hard, once I put it in neutral it wasn't actually moving so should be ok if it happened in traffic but will get it sorted soon as it's stressing me out waiting for it to do it again,,,

Thanks again and will post any developments...

Am looking forward to converting to camper once mechanical problems are sorted....

Regarding Doblo camper conversions: a look at http://www.urbancampers.co.uk/ may give you a few ideas.