4200 surging without touching accelerator

[w1lde1]

Morning,
Having looked through the threads on here i have not seen anything too similar to the issue i faced this morning so thought i would reach out for advice please.

I started her up this morning and put her into reverse and without even touching the accelerator the car started to reverse at speed! quickly applying the brakes very hard did stop her but she was trying to pull back. I popped the car into neutral and all was fine, then into first and the same thing happened. This happened a few times after stopping and starting the car a few times, I could see money floating away with the smell of the brakes

I tried knocking it into second which resulted in the car stalling and when i restarted all was fine.

Has anyone seen this issue before? I do have one error code which is the secondary air filter and other than that she seems to be running well lately.

Thoughts on a postcard please.

Thanks
Daniel

 

[conaero]

When you put her in first or reverse and she moved, what revs where showing?

If ~800 then your PIS point needs resetting or you have a clutch position sensor failure.

Battery reset first is worth a go.

If your revs were ~1000+ then you have an air vaccume leak or a faulty/sticking pedal/TB

 

[w1lde1]

Revs were greater than 1000. Interestingly i did get a clutch sensor error come up a few months back but after resetting the code it never came back.

Vac leak would that knock out a P0492 error (secondary air filter) or is that just a coincidence? I'm assuming sticking pedal as once the car stalled the problem went away (touch wood).

 

[conaero]

The P0492 error is because you have a rusted pipe that runs round the front of the engine and will not affect it at all, it purely is a pump that pumps air into the exhaust on start up to make sure the startup hydrocarbons are burn efficiently in the cold engine.

If you car revs over 1000rpm it will move so your clutch position sensor is not a fault, its the rev input, either you may have had the mat under the accelerator or more likely, your accelerator pedal pot is on its way out, or you have a sticking throttle body.

If it were me, I would take off the pipe from the airbag to engine and spray carb cleaner in there and manually move it to make sure its shutting properly as it sounds like its gummed up and not returning to its closed position fully.

 

[w1lde1]

Thanks for quick reply, sorry being thick this morning (common occurrence) When you say remove the pipe and spray carb cleaner are you referring to the throttle problem or air filter please?

Looking at the diagram on Eurospares i dont see how it could stick http://www.eurospares.co.uk/parts/m...tronic-accelerator-control-valid-for-gd-20930

 

[conaero]

Thanks for quick reply, sorry being thick this morning (common occurrence) When you say remove the pipe and spray carb cleaner are you referring to the throttle problem or air filter please?

Looking at the diagram on Eurospares i dont see how it could stick http://www.eurospares.co.uk/parts/m...tronic-accelerator-control-valid-for-gd-20930

In the engine bay, front of the gold plenum is your Throttle Body. Revolve the pipe and clean it all up.

 

[w1lde1]

Perfect thanks for your help

 

[safrane]

Simple one...are you sure the floor mats are nkt in the way of the peddle?

 

[Zep]

So that I understand this correctly, it idles correctly when in neutral but the revs go high when you put it in gear. Is that right?

 

[w1lde1]

Yes fine in neutral but when in 1st or Rev it moves by its self at speed


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[Zep]

Ok. For me that rules out a mechanical fault like a vacuum leak or sticking TB as both would be present at all times.

You really need to get it on a diagnostic machine to see what it increasing the revs when a gear is selected in my opinion.

 

[w1lde1]

Throttle body off (pain in the bum) all seems to move nicely..... Any other thoughts please. Not happened since so may be a one off.

Going in for some work in a few weeks so will take zeps advice and get it checked


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[w1lde1]

Hi, did it again this morning. Throttle body has been cleaned up, no mat seems to be stuck under the pedal etc.

So just to clarify symptoms. Start the cart put into reverse and the car moves without touching the accelerator, only way to stop the car moving is to hit the brake hard. Put it into first and it does the same.

Neutral the car sits and revs nicely and as expected.

This morning i turned the car off at the battery and did a reset for the pedal, but it did it again once i started up. Shut down everything and tried a third time and this time everything was fine

 

[miket]

Hopefully your gremlin has moved on, hopefully not to a different part of the car!
Keep us posted if the symptoms return.....

 

[mjheathcote]

You could do with a OBD2 reader/scanner that can indicate percentage throttle opening.
I have an 'ultragauge' that plus into the OBD2 port under the steering wheel and one of the parameters it can show is throttle percentage opening.
With this you at least can see if the percentage throttle opening increases when you have the creep...with the throttle in the rested position.
This could then potentially indicate if maybe the throttle pedal potentiometer is at fault.

 

[safrane]

As it only happens when you put it into gear could it be a sensor that prevents stall, clutch position sensor???