C30 with sticking throttle(2010 1.6D R Design)

[Phil Longford]

I am still looking for a reason why my throttle jammed open three times in quick succession, but now cannot get it to repeat itself, and have suddenly come up with one possible solution, which may sound very odd, but here goes.
The throttle mechanism is totally electronic, none of the old fashioned cables, etc. This is the same, or at least very similar to the system used by Toyota, and numerous other car manufacturers today. After my son, to demonstrate the jamming throttle, floored the throttle, and it stuck to the floor, we removed the overmat, and the problem stopped. But I could not see how, if fixed by locating pins, carpet could come into contact with pedal. I was watching a program the other night where The Hamster put fluorescent tubes under overhead power cables, and they lit up, to show how there was in invisible electric force field. This has set me thinking. The car has so many computers controlling everything. Could it possibly be that the new overmats (these are not the old white rimmed R Design mats), are made of a material that either generates an electric charge, or perhaps prevents electric charges from dissipating, and that somehow this affects the electronics on the throttle? We have put the mats back, and it did not jam, but what if my sons footwear also contributed to directing an electric signal to the computer controlling the throttle? It would be easier to blame the carpets coming loose, but I don't think they did. The car is a brand new, 1.6D R Design C30. After this blinding flash of inspiration (which may be complete rubbish) I'm back off to bed!!

[mjcourtney]

Little to no chance of mats or footwear creating enough electromagnetic force to interfere with anything. All of the electronics in the car will be shielded, and any safety critical devices (such as primary controls eg: brakes, accelerator) will be screened to protect against EMC interference.
The power generated by overhead lines produces an electromagnetic field and this is capable of inducing a fair amount of current, as opposed to any static electric that may build up from floor mats / shoes and will deliver a one off high charge shock (but usually only if you earthed yourself). It's not unheard of for car electronic systems to play up when passing close to power lines, and in particular some land based radar installations have also played havoc with ECUs in passing cars. (see http://news.bbc.co.uk/1/hi/england/norfolk/4732096.stm ).

So in summary, no, mats and footwear will pose no electrical danger to any of the controls in the car, but they may well pose a mechanical interference if they become trapped under / over pedals.

[Phil Longford]

Hi MJ
Thanks for the reply. Seems to knock that theory out of the water! It seems like it must be the overmat, getting stuck on the throttle. We have another Volvo which is six years old, with overmats, and have never had a problem with the fixings. In the two months since the new car was delivered, I certainly have not noticed a problem on this C30 with the overmat fixings. The car had been in to the dealer just 2 days before this incident, for its' first 3000 mile check. If the overmats had been loose, surely they would have noticed? Also they are not expected to clean inside at this check, so they would have had no reason to vacuum, or remove the mats. At the moment, the car has had the overmats and the front carpets removed, and what looks like part of the throttle mechanism dismantled, but no repeat of the jamming. Volvo have a copy of the video I took, which hopefully they can enhance, to check to see if the overmat was out of position (which to me seems pretty much the only possible cause!).
According to searches on Google, the top hinged throttle pedal is the only type that gets affected by loose mats. VOSA are very keen to find out what caused the throttle to stick, and will not allow Volvo to return the car to me until it is sorted.

[Phil Longford]

After two weeks with the dealer, Volvo UK have acknowledged that it seems the jamming throttle must have been caused by the mat coming loose, and coming into contact with the base of the throttle pedal.
The chap from VOSA said that all cars should be designed so that this cannot happen, and not only if the overmat comes loose, but also if all weather mats are fitted loosely on top of the normal overmats. This may sound like Health and Safety being a little bit fussy, but after this somewhat scary incident, it makes sense!
The mat fitted as standard to my 2010 1.6D R Design is not the white rimmed type that has always been fitted to R designed cars before, but is a completely black mat. It is slightly thicker than the old mat, and is not as flexible. The pedal, as previously mentioned, is considerably larger on the R Design, than the standard car.
As such, I am sure that all standard cars will meet the criteria issued by VOSA, and could accommodate loose mats on top of the overmats (although I would not recommend this!), but I feel that the larger pedal means that there will always be a chance that, if the mat is not fitted securely, or if all weather mats are put on top, there is every chance that, like mine, the throttle will jam.
Making sure the mat is secure, or removed altogether, means the pedal cannot jam. Another option, as proposed by the dealer, is to change the pedals for standard sized ones. OK, not as stylish, but a solution.
It is now for VOSA and Volvo UK to come up with a proper solution, to avoid any major problems in the future.
I have taken the car back, and am getting in the habit of checking the mat every time. There have been no problems whatsoever.
Be warned though, if you have any R design model with the larger throttle pedal, make absolutely sure your mat never becomes detached, and NEVER put loose mats on top of the secured ones. If nervous, chuck it out!
I will post the VOSA advice when I get it.
Apart from this, I still think the C30 is a great little car.