Engine accelerates when brake pedal is pressed

[buddy57]

I have a 2003 37 foot marlin diesel pusher with a Cummins engine. It is on a freight liner frame.On a recent trip, while coming to a stop and pressing the brake my engine started to accelerate . I had to shut it off and then restart the engine. It was fine for a few more miles and a few more braking episode then it happened again. Very scary! We have disconnected the exhaust brake and it still does it. Cruise control is also off.Our mechanic can't seem to figure it out. Anyone have similar problem or can set me in the right direction. I don't feel safe driving

[Ed_C]

I would be on the phone to Frieghtliner....NOW!

[wolfe10]

While we can speculate/diagnose from long distance, that condition is dangerous enough that you need someone familiar with your drivetrain (likely a Cummins shop) to get this fixed!

[Daveinet]

ScottG wrote:
A similar thing happens sometimes in Dodge trucks.
It happens when a torque converter is not unlocking. When that happens and the computer senses the eng is dropping below specified RPM's, it adds fuel to the eng to keep the revs up. Since the eng is still mechanically coupled to the trans it tries to accelerate.

Not a diesel guy but this makes more sense than anything else. Computer would not through a code because it does not recognize the problem, but is just trying to keep the RPM above a certain minimum. Next time it happens, just put it in neutral. The RPM will probably be normal. It the engine does not continue to rev, then you know for sure that is the problem. If the engine does rev, then you have a different problem.

Hopefully it is not an oil leak in the turbo, or if it starts leaking badly, you will not be able to shut it off

[cross_country]

I would go with rpms too low also and or air in the lines permitting a noticeable surge at no throttle position.

[hershey]

I'd go with ScottT's explanation. That sounds pretty solid to me.

[sjholt]

It seems to me that the "gas" peddle may be sticking.
I know it may be hard to do- but if you can make it happen again, find something to pull up on the throttle peddle and see if it is ok then.

[msturtz]

I assume that your coach has air brakes?
The accelerator on most of the newer units is electronic. You can see if any codes are in the system.

[midnightsadie]

flr matts?

[buddy57]

I sure wish it was my shoes checked that.It only happens when I am just about to a stop ,I have double hit the brake pedal and it stopped doing it .

[rk911]

Johno02 wrote:
I know its silly, but check your shoes. Certain ones of my shoes will hang the edge of the accelerator pedal when steping on the brake pedal.

yup, same here on my 2000 gasser.

[WayneLee]

Ditto Johno02's description. I find that the spacing on my DP between the brake pedal and the accelerator is quite different than on my cars, gas powered trucks, etc. As a result, when I move my foot from the accelerator to the brake, the edge of my shoe occasionally will remain in contact with the accelerator with the result that you describe. It has happened to me so often that when I feel it start, I quickly adjust my foot to stop the problem.

[ScottG]

A similar thing happens sometimes in Dodge trucks.
It happens when a torque converter is not unlocking. When that happens and the computer senses the eng is dropping below specified RPM's, it adds fuel to the eng to keep the revs up. Since the eng is still mechanically coupled to the trans it tries to accelerate.

[Johno02]

I know its silly, but check your shoes. Certain ones of my shoes will hang the edge of the accelerator pedal when steping on the brake pedal.