Freaky acceleration issue

[takk]

Was driving home tonight in my new (< 200 km) 2007 M3 Sport GS (Canada)... we were on the highway, cruise control set at 110 km/hr (~60 mph), in Manual mode (have automatic option), and in 5th gear.

I had just changed lanes when suddenly it was like the car was possessed! It plunged into 3rd gear all by itself and the accompanying huge surge of acceleration had us at 120 km/hr in the couple of secs it took me to cancel the cruise and flick it back into 5th (my first instinct was to go for the clutch pedal... man, old habits die hard!).

A few min later it did it a second time (and under the exact same circumstances -- I had just changed lanes to the right). It did it one more time before we reached home (but this time I was just driving straight ahead -- no signaling, or turning or anything).

Any idea what could be causing this?

I had the cruise control installed by the dealer before I drove the car off the lot. Could it be related to that? The cruise was on when it happened. I'll have to experiment and see if it happens with the cruise off.

I'm worried it's going to be one of those random, intermittent problems that the service guys won't be able to identify. We're making a 1200 km trip to Montreal next week and a problem like this has the potential to be very dangerous on the Quebec highways where it's not uncommon to find everyone driving bumper to bumper at 130 km/hr!

 

[Brian MP5T]

Dealer It.

I have never had that happen in my wifes Mazda 3 Sport..

 

[TheMAN]

OEM cruise control kit or aftermarket cruise control? if I read correctly, dealer installed right? check to see if the car has any ECU updates to it, there were issues with the cruise control on the 04-05 models and an update was released to fix it... does your car have ABS? I've ran into a problem with a 2.3l model with ABS where one of the sensor wires rubbed through and caused an intermittent short which made the signal "dirty" and cause the ECU to freak out... so have them check that also if you have ABS

 

[takk]

OEM cruise control kit or aftermarket cruise control? if I read correctly, dealer installed right? check to see if the car has any ECU updates to it, there were issues with the cruise control on the 04-05 models and an update was released to fix it... does your car have ABS? I've ran into a problem with a 2.3l model with ABS where one of the sensor wires rubbed through and caused an intermittent short which made the signal "dirty" and cause the ECU to freak out... so have them check that also if you have ABS

Now this is interesting to read because the car started doing this on the way home and had been fine on the way there (40 min drive each way). We had to drive down a narrow, deeply rutted, muddy drive-way to get to the house we had been to -- and at one point, going down a very slight incline, the ABS had kicked in very hard when I had barely touched the brakes -- the ABS reaction seemed way over the top. So maybe the two are related. Thanks for the tip. Is there some place I can find out about ECU updates or will the dealer need to do that?

I'm not sure if the cruise was OEM or aftermarket, but the dealer installed (I was in a hurry, they were super busy, and they told me I could just take the car and come pay for the cruise next time I was in the area, so I don't have the paperwork on it).

Thanks for the tip (I would have never connected the ABS with this acceleration issue!).

 

[El Ropo]

This happened to me once (actually twice in 5 min.) about 9 months ago. Took it to the dealer, they couldn't reproduce the problem after 4 days in the shop, so they simply replaced everything related to the acceleration system, and cruise control.

Hasn't happened since, and I've never gotten any type of explanation from them either.

edit.. FYI, I don't have ABS, side curtain airbags,or anything fancy, it's a base model '04 5 door, and the Cruise control is stock.

 

[ZoomVT]

weird issue man, keep us updated on what happens.

 

[Rainman]

Had my MS3 for months now and this has never happened. We have used the cruise on the highway many times and have not had a problem with ith even though we now have 5000 km on the car.

I did report here about unintentional acceleration in m MS3, but this happened twice because of the accelerator pedal becoming stuck behind the all-weather mats. I have removed the drivers mat pending contact from Mazda Canada and have not had the problem since. I could easily cut the mat, but I want Mazda Canada to be aware of this before I do that.

R