Hi, I've got an issue that I'm hoping someone will be able to help me resolve.
My parents have a 2008 Ford Expedition with the 24V 5.4L V8 and 6R75 transmission. It's got about 130,000 miles on it. The problem that we're experiencing with it is heavy shuttering when it's accelerating in 6th gear below 60 mph. The front end jolts and vibrates under a load, or going up a hill in 6th. If we press the accelerator down further and it shifts into 5th, 4th, 3rd, 2nd, or press the overdrive off button, it exhibits no shuttering at all and performs just fine. We've researched this extensively, and see that it's happened with a lot of the F-150s with 6 speeds as well as some of the F-150s and Expys with the 24V 5.4s and 4-speed trannys. I can't seem to find any 6-speed Expeditions that have this problem though.
A lot of them say that there is a TSB for the transmission coding, PCM, torque converter, what have you, and they'll go to the dealership to have it re-flashed. We have done pretty much every other thing except this. We know the causes of the infamous shuttering since we had a 2001 Expedition 5.4 for 15 years and did the routine spark plugs and coils. So, for the 2008, we changed the spark plugs(to the redesigned SP-546 with no blue weld lines), coils, both camshaft position sensors, and the crankshaft position sensor, but even after all of that, it still had the same shuttering.
Now, here are some symptoms that I don't see a lot of people talking about that we have noticed with ours: when the engine and transmission temperatures are still cold, and when I get it up to speed and it locks into 6th, I'll accelerate it and put it under a load in 6th, but no shutter. After a while when the temperature gets warmer, the shutter will come back. If it's cold outside, it'll take a longer for all of it to warm up and so it'll take a little longer for the shuttering to begin. The next thing is when it shutters, the tachometer will fluctuate upwards slightly by around 100 rpm. Whenever we let off the accelerator, no more shuttering, and no more tachometer fluctuations. The last thing, (and maybe this will be able to shine some light on the true cause), when the shuttering happens, it can be at random intervals, but most of the time it has a set sequence. It will shutter for about 1 to 2 seconds, then stop for 1 to 2 seconds, and then shutter again for 1 to 2 seconds over and over. The strange thing is when I take it out of overdrive(just pressing the O/D button and maintaining speed, no hard accelerations from mashing the accelerator), there will be this humming noise. Almost like the sound a transmission would make when "gear-hunting", and it will have the same intervals as the shuttering. It'll start, stop, start, stop, in sequence.
The only thing we can see doing now is taking it to the Ford dealership and having them do a test run/diagnostics scan of it, or seeing if they've had similar problems with other 6-speed Expeditions and have a solution for this issue.
Any thoughts, information, or solutions ahead of time is most appreciated.
Thanks in advance!
My parents have a 2008 Ford Expedition with the 24V 5.4L V8 and 6R75 transmission. It's got about 130,000 miles on it. The problem that we're experiencing with it is heavy shuttering when it's accelerating in 6th gear below 60 mph. The front end jolts and vibrates under a load, or going up a hill in 6th. If we press the accelerator down further and it shifts into 5th, 4th, 3rd, 2nd, or press the overdrive off button, it exhibits no shuttering at all and performs just fine. We've researched this extensively, and see that it's happened with a lot of the F-150s with 6 speeds as well as some of the F-150s and Expys with the 24V 5.4s and 4-speed trannys. I can't seem to find any 6-speed Expeditions that have this problem though.
A lot of them say that there is a TSB for the transmission coding, PCM, torque converter, what have you, and they'll go to the dealership to have it re-flashed. We have done pretty much every other thing except this. We know the causes of the infamous shuttering since we had a 2001 Expedition 5.4 for 15 years and did the routine spark plugs and coils. So, for the 2008, we changed the spark plugs(to the redesigned SP-546 with no blue weld lines), coils, both camshaft position sensors, and the crankshaft position sensor, but even after all of that, it still had the same shuttering.
Now, here are some symptoms that I don't see a lot of people talking about that we have noticed with ours: when the engine and transmission temperatures are still cold, and when I get it up to speed and it locks into 6th, I'll accelerate it and put it under a load in 6th, but no shutter. After a while when the temperature gets warmer, the shutter will come back. If it's cold outside, it'll take a longer for all of it to warm up and so it'll take a little longer for the shuttering to begin. The next thing is when it shutters, the tachometer will fluctuate upwards slightly by around 100 rpm. Whenever we let off the accelerator, no more shuttering, and no more tachometer fluctuations. The last thing, (and maybe this will be able to shine some light on the true cause), when the shuttering happens, it can be at random intervals, but most of the time it has a set sequence. It will shutter for about 1 to 2 seconds, then stop for 1 to 2 seconds, and then shutter again for 1 to 2 seconds over and over. The strange thing is when I take it out of overdrive(just pressing the O/D button and maintaining speed, no hard accelerations from mashing the accelerator), there will be this humming noise. Almost like the sound a transmission would make when "gear-hunting", and it will have the same intervals as the shuttering. It'll start, stop, start, stop, in sequence.
The only thing we can see doing now is taking it to the Ford dealership and having them do a test run/diagnostics scan of it, or seeing if they've had similar problems with other 6-speed Expeditions and have a solution for this issue.
Any thoughts, information, or solutions ahead of time is most appreciated.
Thanks in advance!