Sudden unexpected acceleration...

[tsunami]

Sudden unexpected accleration!!!
This afternoon I started my 2015 Mustang Turbo convertible...as I put it in reverse, the engine sped up to nearly 4000 RPMS, without my foot on the gas pedal. I put down 20 foot long burn marks in the pavement before I could stop the car and shut off the engine. After catching my breath...I kept my foot on the brake pedal and pushed the start button...the engine immediately revved to over 3000 RPM. I immediately hit the stop button. Over the next 15 minutes I tried to start the car 5 or six times and it repeatedly over-revved each time. The tow truck never showed up...so after two hours of waiting...I carefully started the engine and it started normally. I slowly drove the two miles to the local dealer without incidence, where it now sits for a diagnosis.
Has this ever happened to you...unexpected acceleration with touching the gas pedal. I know that some people may mistakenly hit the gas pedal instead of the brake. But this malfunction occurred repeatedly while my foot was on the brake and I started and shut off the engine without putting it into gear.

I should mention that I had replaced the battery two days before. The battery had been out for several days. I had driven 20 miles to the parking lot where the incident occurred without any engine malfunction.

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[Fatguy]

Well it’s drive by wire now so anything can happen. There is something amiss. I would say - are you sure you were pressing the brake only? As in you didn’t slide the mat or something over the accelerator but under the brake. Ford is crazy about anchored mats and that is the reason why. You can’t even place the rubber mats over the anchored cloth mats for example. If not then into the shop it goes.

I have inadvertently hit the brake and accelerator with my foot a few times and it’s unnerving till you figure out it was your fault all along.

 

[Blue Moon]

Manual or automatic?

 

[TaraFirma]

Manual or automatic?

Really?

On another note, who did you call for a tow that never showed up? That would have pissed me off.

 

[Lime1GT]

I had a 92 Lincoln LSC/SE that the throttle would rise all on it's own. Found it was the TPS {throttle position sensor}. It wouldn't come down unless I restarted the car. I know, EECIV as compared to OBDII but just a suggestion.

 

[thehunterooo]

Toyota Mustang

 

[Dave TBG]

I suspect the brake was not actually applied at the time, the brakes are powerful enough to stall the engine with a manual trans, the car wouldn't have moved, let alone left 20' marks on the pavement with the brakes on.

 

[tsunami]

To answer your questions...
When the first reverse acceleration occurred...I wondered if somehow I had hit the gas pedal, maybe my foot fell off onto the gas pedal by mistake.
I normally only apply a slight amount of pressure to the brake pedal when I start the engine. The engine started normally. I put it in reverse (automatic transmission) and the engine immediately screamed up to 3000 rpms+. I quickly hit the brakes hard while also hitting the stop button. I left a cloud of burnt rubber and 20 feet of rubber on the pavement within a second or two. So yes...I guess I could have accidentally hit the gas pedal...but I never slam on the gas, especially when I am backing up!

On the second attempt, I made sure that my right foot was stomped hard on the brake when I hit the start button...the engine started normally and then in a second or two it revved to over 3000 rpms, in park! I tried several more times...same result. So....no accidentally pressing on the gas pedal!

My floor mat was on the floor, not bunched onto the gas pedal.

I called the Ford Road Assistance hot line...they got the information including my location and my cell phone number. They said the tow truck would be there in less than 1/2 hour. I was in the city limits at a park. The local Ford dealer is only about 1 mile from the park. No calls from the tow company. It turns out that NO auto dealers in that town have tow trucks. They all depend on independent companies to tow disabled vehicles to their dealerships
.
With no tow truck arriving after two hours...I tried it again...this time the Mustang started and idled normally. I slowly drove to the dealer. I was told that if you drive the Mustang slowly, you can hit the stop button and the engine will shut off.
Drive faster and the stop button is disabled. So driving slowly...I felt I could shut the beast down if it decided to over-rev.

The Ford dealer had no idea who Ford Road Assistance had called for my tow. The dealer simply said "Who cares if the tow truck arrives at an empty parking lot, after you waited two hours, as long as you got here safely".

Anyone heard of the Mustang's electronics going crazy after having no battery power for several days....and then power restored from a new replacement battery?

 

[Dave TBG]

The second time, 3000 rpm instead of 4000 rpm and no movement, that time your foot was on the brake. I didn't mean to imply that there wasn't anything wrong, but actually moving 20' with the brakes on requires complete hydraulic system failure and the brakes would not have worked properly on subsequent attempts to start the car.

 

[tsunami]

"DaveTBG": you misread my report. I don't normally stomp on the brakes when I attempt to start the Mustang. I just apply enough braking to allow the engine to start. After the engine started, I moved the gear shift to Reverse.and took my foot off the brake pedal..and the engine proceeded to jump to somewhere between 3000-4000 rpms...I didn't have the time to carefully watch the tach while the Mustang was burning rubber! I don't stomp on the gas pedal especially when I am backing out. I had to react as fast as possible to stomp on the brakes and hit the stop button.
My subsequent attempts proved to me that there was something wrong when she jumped to 3000 every time I simply hit the start button.

I now realize the amount of criticism that Toyota owners came under when their cars proceeded to speed up without the owners input. "It had to be the owners...because it is impossible for cars to accelerate without the idiot drivers causing the problems."

I know what I did and how the Mustang acted...you weren't there...and I hope your Mustang doesn't develop the same problem...because it would be obviously your fault whatever happens!

I thought it was important for other Mustang owners to be informed of my situation...but it is obvious nothing could ever be wrong with a Ford Mustang!
So I shall not respond to this Forum any farther about this problem...the NHTSA has already asked me about it and wants some follow up.

 

[Shifting_Gears]

Good luck getting it sorted out. Things get scary when electronic everything has the potential to malfunction.

 

[TaraFirma]

Keep us updated on what the dealer finds and tells you.

 

[Dave TBG]

"DaveTBG": you misread my report. I don't normally stomp on the brakes when I attempt to start the Mustang. I

Doesn't look like I misread anything, on the contrary, you missed the point. As I said previously, I'm not implying that there's not something wrong with your car, but the fact that it went twenty feet is pure operator error.
I'm old enough to have been driving back when cars didn't have an interlock that required you to apply the brake (or clutch) when starting the car or shifting out of park. That interlock was one of the first "driver aids" put in place to save us from ourselves. You seem to have found a work-around for that nanny and, well, I'm glad you weren't hurt.

 

[Hack]

Definitely if the car moved and spun the tires you weren't stepping on the brake hard.

 

[cbrookre]

Definitely if the car moved and spun the tires you weren't stepping on the brake hard.

To give the OP the benefit of the doubt, the surge could have been semi-delayed and not have happened until just after releasing the brake to start creeping backwards. As stated above, we are conditioned through repetition to expect a certain behavior when we do a specific thing or set of things. We generally drive our car as if everything were still mechanically connected despite it not actually being that way anymore. When the electronics give us something different then it takes us a moment to react. I am sure that the OP did not go out with a tape measure and verify that the marks were 20ft, probably very high error bars. Anyway, scary situation, glad you were not hurt or someone was not behind you and got hurt. Get it checked out, but I fear that you are going to get the typical "could not replicate, return car to customer" response here.

On a side note, that is why I personally am not looking forward to self-driving cars. Like to be in control as much as possible, and if I make a mistake then I alone bear the blame.

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