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Still death-traps on the road

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dnix71:
This has been going on since car makers went from mechanical throttle to fly by wire. My neighbor has a 2001 Mercury 6 cyl. that he was working on Friday and needed an 8mm wrench to replace a component again. I loaned him a socket wrench and asked what the trouble was. He was replacing the swirl control valve again, thinking that was why he had sudden acceleration.

People used to joke that it was operator error, mistaking the gas pedal for the brake, but he showed me in the parking lot in park, start the car and it would idle normally for a few seconds and then full throttle (4000k rpm) and not back down until shut off. It was so dangerous to drive he had parked it until he could verify the fix.

Google the term "sudden acceleration" and your car model and you will likely get real returns. Ford willfully refused to deal with this for 10 years. In my neighbor's case, it could be the swirl valve or it's gasket, or the throttle position sensor or as he found, the cruise control cable slipping out of place. A 10 cent wire tie fixed it.

I would curse Ford, but Toyota had problems, Audi had problems, pretty much anyone that went to fly by wire could have a condition where the computer would go runaway throttle. Maybe I should curse Ford, though, because the simple 2 fixes are easy and universal. I saw a car 15 years ago with a programmed throttle limit. If you floored the pedal in park or neutral the ignition would cut off at 2k and resume when the rpm dropped back below that and hang and surge around 2k. The other fix, which I hear is now almost universal, also prevents people from driving with 2 feet. Brake Override causes the engine to drop to idle when the brake is depressed, no matter what any other input says. Engine runaway for any reason stops immediately when the brake is tapped. You also can't drive with 2 feet, because with your foot on the brake even slightly the engine won't come up above idle.

frackers:

--- Quote from: dnix71 on March 04, 2017, 07:36:29 PM --- You also can't drive with 2 feet, because with your foot on the brake even slightly the engine won't come up above idle.

--- End quote ---
As well as getting rid of that constant and extremely irritating brake light when peeps drive like this!

george65:
I see those types and wonder how the fact they have to be constantly going through brake pads doesn't give them or their mechanic a clue to have a chat with them on how to drive correctly.

The ones I would like to have banned from the roads are the incompetent morons whom go down a hill 20 under the limit with their foot on the brake and slowing more for every turn.  Then going back up the other side on just as tight bends, they do the limit or over.
Went a couple of places yesterday and was going nuts with people doing this. The competency of drivers just keeps getting lower and lower.

As for the runaway fly by wire, on older vehicles there should be known fixes not to rectify them and on later vehicles I'm pretty sure the problem has been cured long ago.

I much rather have a runaway engine than a brake failure.

OperaHouse:
I had that problem with a Ford Explorer. I would be stopped and suddenly the rpm would jump to over 2,000. Dis this a couple of times.   I was able to get to a parking lot to see if I could find the problem, I shut off the engine.  Didn't see anything obvious.  I was lucky to be charging a SLA battery from the lighter socket.  Had a small ohm resistor to limit current in series with the battery.  When I tried starting the car that resistor went up in smoke.  Opened the hood to look at the battery and one of the terminals had a cracked connector.  Evidently while being stopped a spike on the 12V line reset the computer.  It thought the engine was being started and opened the Idle Air Control Valve fully.  Didn't have a problem for years after that was fixed.  Just try telling that story to a cop after rear ending someone at a stop light.

JW:
Im a re-certified ASE master tech (over 20 years) and Advanced level specialist.

We first saw these type of malfunctions even with a throttle cables. It comes from the TPS (throttle position sensor) Now the TPS is built into the drive by wire throttle body.

The drive by wire system should be protect that condition by going into limp in mode. The gas pedal sensor has a Potentiometer that will be read by the computer there is a x pattern so one reading goes from high to low and another going low to high ohms.

The throttle body has the same arrangement with the tps.

So considering the protective circuit on each what your experiencing should be impossible, suspect the ECM. There is a manual way to check the pots and if you detect the a bad sensor the commander ECM.

If you have OBD11 scan tool you can access the signals from the data list and its an easy way to verify the TPS readings.     

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