2010 F150 4.6L WOT with foot off the pedal
#1
07-07-2016, 08:29 AM
2010 F150 4.6L WOT with foot off the pedal
I got in a work truck yesterday, sat down, put my seat belt on and started the truck. Just as I did that another employee drove by and waved, all I could do was nod back at him because my hand was still starting the truck. This took my attention away for a split second, then as I put the truck in gear, my foot still on the brake, I noticed that the tachometer was pegged and the engine was racing. I instinctively pushed harder on the brake pedal, then looked down to be sure that I was pushing on the brake pedal and I was. Right then then rear of the truck started shaking violently and as fast as I could I turned the key off and put it back in park. This all happened in about 1 second, maybe 2.
The shaking was caused by the sheared off driveshaft. And it was sheared off because the center section of the rear differential had broken the spot welds that hold it and place and rotated on the axel housings. It is now pointing upward towards the bed of the truck.
Anybody else ever have a drive by wire truck run the engine at wide open throttle with no input from the pedal?
**I'll try to get the pics posted soon**
The shaking was caused by the sheared off driveshaft. And it was sheared off because the center section of the rear differential had broken the spot welds that hold it and place and rotated on the axel housings. It is now pointing upward towards the bed of the truck.
Anybody else ever have a drive by wire truck run the engine at wide open throttle with no input from the pedal?
**I'll try to get the pics posted soon**
#3
07-07-2016, 09:36 AM
#4
07-07-2016, 09:45 AM
The truck has about 151,000 miles on it, and we just had the rear differential rebuilt. It only had a side bearing failure, but the other guy driving it never had it fixed, so the bearing slowly filled the oil with metal and that ruined everything else in the differential.
I just don't know why the engine was at full throttle without any input from the pedal.
I just don't know why the engine was at full throttle without any input from the pedal.
#6
07-07-2016, 10:26 AM
Holy crap!
Can't accuse the 4.6 of not having enough power, eh?
My guess would be a sticky / faulty pedal assembly. We had this happen on a superduty at work a few years ago. The pedal would catch about 1/4 throttle and not return to zero reliably.
You need a scanner that can look at live data. Either the output from the pedal is wrong, or the output from the pcm is wrong or there is something physically blocking the throttle body open. But the live data is going to be your smoking gun.
Must not be WOT, though. At WOT the fuel injectors wont fire so the truck wouldn't have started.
Wow ... Just ... Wow!!!
Sorry to see this happen to you.
Any chance the shop doing the rear end work had to mess with the tube/ housing connection? Outside of racing, I've never seen those welds break unless someone who didn't know what they were doing did the repair weld. Not to say it couldn't happen, I've just never seen it.
Can't accuse the 4.6 of not having enough power, eh?
My guess would be a sticky / faulty pedal assembly. We had this happen on a superduty at work a few years ago. The pedal would catch about 1/4 throttle and not return to zero reliably.
You need a scanner that can look at live data. Either the output from the pedal is wrong, or the output from the pcm is wrong or there is something physically blocking the throttle body open. But the live data is going to be your smoking gun.
Must not be WOT, though. At WOT the fuel injectors wont fire so the truck wouldn't have started.
Wow ... Just ... Wow!!!
Sorry to see this happen to you.
Any chance the shop doing the rear end work had to mess with the tube/ housing connection? Outside of racing, I've never seen those welds break unless someone who didn't know what they were doing did the repair weld. Not to say it couldn't happen, I've just never seen it.
#7
07-07-2016, 02:05 PM
Trending Topics
#8
07-07-2016, 04:29 PM
Id agree, i just am surprised that they would be bad from the factory. Unless it just sheared it clean. Looks like a whole new axle is in your near future...
Check with your insurance company, many have an "unintentional destruction" clause that might help.
I knew a kid who got a new transmission after the pcv breather filter dislodged and jammed his throttle blade wide open and he decided to drive it anyway. He got another transmission after taking his car to an open drag night at the strip ... Course his dad was an insurance agent, so that helped him out more than just a little.
I'd check that route for sure before eating another axle.
Check with your insurance company, many have an "unintentional destruction" clause that might help.
I knew a kid who got a new transmission after the pcv breather filter dislodged and jammed his throttle blade wide open and he decided to drive it anyway. He got another transmission after taking his car to an open drag night at the strip ... Course his dad was an insurance agent, so that helped him out more than just a little.
I'd check that route for sure before eating another axle.
#9
07-07-2016, 10:49 PM
Wow...very interesting. That truck has the 8.8" rear axle, which is the lighter of the two offered that year. Still surprising that it failed like that, I don't think I've ever seen a photo like that.
Seems really fishy to me that the rear axle would fail at the same time as the throttle pedal.
Seems really fishy to me that the rear axle would fail at the same time as the throttle pedal.
#10
07-07-2016, 11:39 PM
Looks to me that one caused the other.
I'm guessing the extreme torque load caused the plug welds to break and let the pinion rotate up, which caused the driveshaft failure.
I have no problems believing that there is a throttle problem, be it electrical or mechanical, I just can't believe the welds broke....
Rock crawlers and drag racers break them in this manner, but I'm just astonished that a stock truck can break a stock axle.
I'm guessing the extreme torque load caused the plug welds to break and let the pinion rotate up, which caused the driveshaft failure.
I have no problems believing that there is a throttle problem, be it electrical or mechanical, I just can't believe the welds broke....
Rock crawlers and drag racers break them in this manner, but I'm just astonished that a stock truck can break a stock axle.
#11
07-08-2016, 07:15 AM
Yeah, I can see how that could happen if the axle was weak. My point is just that both are failures I've never heard of. The electronics and programming of the electronic throttle system are supposed to prevent that from happening, and the 8.8" axle has been in use for over 30 years. The only folks I've ever heard of who brake axles are drag racers or rock crawlers. A stock truck did this?
My '97 Lincoln had that very same axle, and you know what I put that thing through.
I'm not doubting the OP's testimony, just that it's enough of a coincidence that it's tough for me to believe.
My '97 Lincoln had that very same axle, and you know what I put that thing through.
I'm not doubting the OP's testimony, just that it's enough of a coincidence that it's tough for me to believe.
#12
07-08-2016, 10:53 AM
Found this interesting ...
Brake-Throttle Override Becomes The New Standard
Brake-Throttle Override Becomes The New Standard
Ford
Ford began migrating brake-throttle override, or Brake Over Accelerator (BOA), as the automaker calls it, in 2004 and the first product it appeared on was the 2005 Ford Escape Hybrid. By the end of calendar year 2010, it was implemented on nearly 100 percent of Ford and Lincoln light-duty models (excluding select low volume vehicles, such as certain trucks with a Cummins diesel engine). Owners of these trucks may not want BOA because they are backing up trailers or putting boats in the water, etc.
Brake Over Accelerator is a Ford-designed system. It is on manual and automatic transmission vehicles and operates the same. BOA is also on Ford hybrid and electric vehicles but operates a little bit differently than conventional powertrain vehicles. The system works the same way but the software calibration is a little different.
The BOA system monitors the accelerator pedal and the brake pedal position. If it senses brake pedal application and accelerator position not changing (for example, the accelerator is stuck or trapped), the electronic throttle is driven closed to idle position by the powertrain control module. As the throttle is driven closed, the brake force acts on the vehicle and it slows down—to a complete stop if the driver continues to apply the brakes.
Ford says that the system acts “very quickly.” When the brake is released, the system resumes normal operations, but the throttle is ramped back to the requested pedal position to allow a controllable acceleration. It also works in reverse.
Ford began migrating brake-throttle override, or Brake Over Accelerator (BOA), as the automaker calls it, in 2004 and the first product it appeared on was the 2005 Ford Escape Hybrid. By the end of calendar year 2010, it was implemented on nearly 100 percent of Ford and Lincoln light-duty models (excluding select low volume vehicles, such as certain trucks with a Cummins diesel engine). Owners of these trucks may not want BOA because they are backing up trailers or putting boats in the water, etc.
Brake Over Accelerator is a Ford-designed system. It is on manual and automatic transmission vehicles and operates the same. BOA is also on Ford hybrid and electric vehicles but operates a little bit differently than conventional powertrain vehicles. The system works the same way but the software calibration is a little different.
The BOA system monitors the accelerator pedal and the brake pedal position. If it senses brake pedal application and accelerator position not changing (for example, the accelerator is stuck or trapped), the electronic throttle is driven closed to idle position by the powertrain control module. As the throttle is driven closed, the brake force acts on the vehicle and it slows down—to a complete stop if the driver continues to apply the brakes.
Ford says that the system acts “very quickly.” When the brake is released, the system resumes normal operations, but the throttle is ramped back to the requested pedal position to allow a controllable acceleration. It also works in reverse.
#13
07-20-2016, 03:55 PM
I've got no reason to lie. I had my right foot FIRMLY planted on the brake pedal. I even looked down when I heard the engine racing to be sure that I wasn't pushing on the wrong pedal. The truck is sitting at the dealership and they say they haven't been able to replicate the WOT problem and that it didn't set any codes.
I think the rear end would have normally held up to that 1 second of full throttle with the brake applied. The crystalline structure of the weld shows that it didn't have any penetration. Once it let loose all the other damage happened...IMO.
I think the rear end would have normally held up to that 1 second of full throttle with the brake applied. The crystalline structure of the weld shows that it didn't have any penetration. Once it let loose all the other damage happened...IMO.
#14
07-20-2016, 09:58 PM
Trust me, friend. Your reputation precedes you; no one here is questioning your integrity or motivation.
This is just a really strange failure. Outside of extreme powersports it is almost unheard of.
FWIW, I tried the brake over throttle in my 2010 work truck and could not get the computer to intervene. I set the throttle down such that the truck drove forward and applied the brake until something happened. All I could get it to do was a full abs skid as it powered down the road (gravel).
It looks as though the BOT may not work that well in 2010 ....
This is just a really strange failure. Outside of extreme powersports it is almost unheard of.
FWIW, I tried the brake over throttle in my 2010 work truck and could not get the computer to intervene. I set the throttle down such that the truck drove forward and applied the brake until something happened. All I could get it to do was a full abs skid as it powered down the road (gravel).
It looks as though the BOT may not work that well in 2010 ....
