Mrs V returned home from work about an hour ago and was vert shaken.
She was travelling on the M4 travelling gently accelerating in 5th gear from 60 to 70. However the engine kept increasing in revs when she eased off the accelerator and she then took her foot off the accelerator completely. Revs and speed kept increasing and the car was very quickly at 85 and still accelerating.
She started to press the brake pedal and it felt hard it wouldn’t move and the car was still accelerating.
She then pressed the clutch in and hit the brake pedal as hard as she could - moving it down into 4th to try and get it to slow down. It then started to slow down but with very high revs. There was a smell of burning rubber.
After making a terrific noise (over - revving I suspect) she describes the hard brake pedal as suddenly freeing up and working as normal.
She continued the remaining 5 miles to home at a low speed.
I have just taken the car out along the local country lanes taking it through all of the gears and accelerating hard then the motorway at up to 85. Everything seems fine.
I have a Mazda service centre just round the corner and I am going to book it in there for a thorough check - in the meantime it will remain on the drive.
Meanwhile has anyone got any ideas re this?
I cant think what would affect throttle control and braking function at the same time in this way.
Its a 2007 MK3.
Sometimes it can be something simple. Are the mats securely fitted. A mat pushed forward can press down on the accelerator and stop the brake pedal going down.
First thing I asked
She says that it was exactly where it should be
When I drove the car, I double checked - it was still in the right place
Possibly an induction air leak. I’d check the pipe work to the brake servo.
I had a sillier experience with my MK3 and found the mat had got jammed somehow. Very frightening.
NC is drive by wire. Cruise control issue? I would get it checked out by a dealer.
Thanks for that folks - given me a few things to think about
I will book it into the Mazda specialist asap
100% a floor mat problem, it slides up towards the pedals as you drive. This happened all too frequently in my mk3. I’ve put double sided tape on the bottom of the mat to stop the riding up but still bend down and give the mat a good tug back before every journey.
Thanks once again all
I also posted about this on the watch forum I frequent which has a lot of MX5 owners
As on here there have been many posts regarding the floor mat with a number saying that they have experienced exactly the same thing
I do recall a similar occurrence in my MK2.5 after it had been valeted - however, it was obvious that the cleaner had just pushed the mat back in a haphazard way and part of it had gone over the top of the accelerator pedal. (I have fitted heavy duty rubber mats from MX5 parts to both cars)
Mrs V is adamant that the mat was not interfering with the pedals - but as she so shaken up by things perhaps she wasn’t thinking quite straight?
As regards the other potential causes such as split pipes, ECU etc - would these be intermittent I nature? Perhaps.
Anyway, this morning I am going to experiment with pushing the mat forward in various ways to see if I can replicate the problem
I also have had this same problem in my 3.5. Very frightening. I threw the mat in the bin.
My mate had it happen on a Vauxhall. It was the crank sensor in his case.
Hi Velorum
If you need to replace the clips that hold the drivers side mat in place these seem rather popular.
Well Ive fiddled about with the mat a while:
Simply pushing it forward as far as it will go doesn’t seem to interfere with the pedals in any way that I can see
If the end is folded back on itself and then rammed all the way forward it does interfere with them but try as I might I couldn’t get the accelerator to stick open
Putting the mat on top of all of some of the pedals has the biggest effect and will make the accelerator stick open especially of the brake or clutch are depressed - however I cant see how Mrs V would have not been aware of this - and she did say that she checked the mat after she had slowed down. She was in an anxious state though and perhaps with all the frantic pedal pushing and gear changing it had flopped back into place?
Ive removed it from the car anyway
.
I have had exactly the same thing happen twice. In both cases it was changing into fifth and did not get it quite right which sent the revs all the way up and jammed there.
The first time got the car to stop but brakes were no working very well (no servo). Restarted and everything was ok. I just put it down to the rev limiter jamming (Only a Guess).
Probably not the cause.
The second time, i just dipped the cluch and turned the egnition off and on again, clearing it and carried on thrashing it. I’m not sure why it does it, but I expect it will happen again unless I change my driving habits. I did not have any car mats in the car.
If youre adamant that the mat was not to blame, then the only other ting I could think of would be the throttle position sensor, or sticking cruise control (if fitted).
Dipping the clutch or touching the brake ought to have canecelled this out though.
Cruise Control was not fitted as standard until the NC2 or Mk3.5 very late 2008 but in reality due to over stocking of the old model, tended to be well into 2009.
The OP’s car is 2007 but maybe cruise control was a factory option then.
What ever the reason not a good place to be for the Lady in question.
Another vote from me for the mat. I had exactly the same problem with my Sport Graphite the mat slipped forward and accelerated the car in a 30mpg limit! I had only had the car 1 day and the mats had been incorrectly fitted. Suffice to say the dealer got to hear about it!
Over the past few days I have covered about 250 miles (without the floor mat!!!) on a variety of roads at speeds at low and high speeds.
I have not been able to replicate the problem.
The only thing I have noted that is different to my MK2.5 is that if you blip the throttle the revs don’t drop smartly and smoothly back to idle - they sometimes drop then increase for a split second before falling again, it feels like a slight and momentary surge. It seems to make no difference under load and normal driving etc though.
At this point I am wondering whether Mrs V some how rucked up the mat in such as way as to directly affect the pedals and in the ensuing panic didn’t notice this and that it had returned to normal?
It is a difficult situation as you were not the person who experienced the problem either directly or indirectly - you weren’t there when it happened.
Adding to the confusion is another poster above saying that they had the same problem with no mats in the car but no real idea what caused their problem or solution.
If it wasn’t the mat there is something really strange going on as you have high revving at the same time as the brake servo appears to have stopped working.
To have an acceleration issue as well as a braking problem with no engine management light seems unlikely. Have you check the OBD to see if there are any error codes stored? Just thinking there may be a problem with the EML.
Obviously and understandably frightened the hell out of your wife so whatever it is needs to be resolved.
Sounds like you have already done what I would do - swap cars and thrash the MK3 to try and make some sense of it.