Well on my way to work this morning i was coming up to a school bus, i down shifted like always and while the truck was engine braking i applied the brakes as soon as i pushed in the clutch to downshift another gear the truck idled down but didnt stop it got to about 500 rpm sputterd a few times i tried to save it but *** soon as i touched the peddle it died. It did it again on my way home but this time when it fell to about 4 or 500 it saved itself and kept running (im guessing if i touched the peddle it would have died. Now the only repeating conditions i see are that it was while engine braking and while hitting the brakes. Oh and as soon as it happened the service engine light came on. So i am going to get it scanned asap but until then any ideas? i got a pretty bad missfire at idle as well that you can hear through the exhaust.

Here is a little info on the truck most is in my sig though, 2000 f250 5.4l 5 speed manual. Rebuilt about 3500 miles ago by me. All stock except a magnaflow catalytic converter and a flowmaster super 10. Im really curios about my missfire since the motor is fresh and i only run premium i dont really know what it could be.

Thanks for any help guys, Cody

 

The code was for the vehicle speed sensor. cruise control just stopped working and my speedo is going crazy. But i dont understand why its stalling? I can make it stall if im deceleratting and i hit the brakes and turn at the same time. I dont know what this has to do with the vehicle speed sensor but it seems to me like the power steer and power brakes are putting to much of a load on the motor

 

The list of things that could cause symptoms similar to what you describe is too long to list here. If you want to look for something while waiting for a diagnostic trouble code to show up, raise the hood and do a good visual inspection. You need to be looking for a possible vacuum leak, particularly around/at the brake booster since braking contributed to the problem and the miss was at idle. Also look for any loose electrical connections and anything that looks loose or out of place.

Oh, and always fix known problems before doing additional troubleshooting. Go ahead and look at the speed sensor and wiring.

Good luck with it. Post back what you find.

 

ive given a good visual check because vaccum leak was my first guess as well but everything checks out and i just had the motor out and all the lines looked good. Im going to get the speed sensor changed and see if that helps.

 

Does it idle OK?

 

Sounds like the speed sensor is putting it in limp mode.

Are you lugging the engine too much? When it gets low RPM's and still in gear braking it could be lugging.

 

Are you using an aftermarket chip or programmer?