2008 Ford Expedition shuttering in overdrive in low rpms

[copper]

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!

 

[JExpedition07]

Some have had a vibration or a "rumble strip" condition in O/D and have had luck with a tranny fluid change with a new filter.... might be worth a shot. The friction modifier in the Mercon SP wears out and the TC will struggle to stay locked in. If the fluid change does nothing it will most likely need a new torque converter. This issue has been known to rarely occur in all the 6R75 and 6R80 transmissions used across various models and years.

 

[bobmbx]

Tranny fluid change. If you take it to a dealer, they're going to tell you that you need a new transmission. its a lot cheaper to change the fluid and see if thats the solution. I'd say that 99 out of 100 times, this will cure the issue. I've done it on two of my own and it worked.

 

[copper]

Thanks for the quick replies, guys. I figured it had to be something with the TC or fluid and filter. I did notice a lot of people stating that the fluid and filter change fixed the problem most of the time. We do all of the maintenance on our vehicles ourselves, so we'll tackle that instead of the dealership. Since we're pressed for time at the moment, we'd rather not change them and find out it was actually the TC and run the risk of wasting time and money, so we're gonna take it to Yaklin Ford just to see if they can give us an answer as to which one has a higher chance of being the culprit from their scanner's point of view. I dealt with them in the past when I needed a speedometer re-calibration for my 2005 and they were pretty decent. They charge $125 for a full systems check and diagnosis, and didn't charge any extra for the re-calibration. If they can give us some extra information on it, great, we'll aim in that direction. If not, no problem, we'll go for the filter and fluid and change it ourselves. We just don't wanna waste time on this repair since we've got a lot going on.

I'll let ya'll know how it goes. Thanks again!

 

[JExpedition07]

That's tough, I can almost guarantee you they will tell you a new tranny like bobmbx said. The scanner is going to say the TC is not staying engaged and the diagnosis will be a new TC is needed according to the scanner. Many people have gotten to the point of arguing with the mechanics over it. The scan tool cant tell them the friction modifier in the fluid is worn out. Fluid changes on these trans are a pain... I topped mine off after having my fluid and filter change and its bizarre. You have to have your arm against an up to temp catalytic converter, there are ways around that if your creative. It is possible, again just bizarre. If you decide to tackle it get Mercon SP for the 6R75, you will also need one of these:

 

[bobmbx]

Thanks for the quick replies, guys. I figured it had to be something with the TC or fluid and filter. I did notice a lot of people stating that the fluid and filter change fixed the problem most of the time. We do all of the maintenance on our vehicles ourselves, so we'll tackle that instead of the dealership. Since we're pressed for time at the moment, we'd rather not change them and find out it was actually the TC and run the risk of wasting time and money, so we're gonna take it to Yaklin Ford just to see if they can give us an answer as to which one has a higher chance of being the culprit from their scanner's point of view. I dealt with them in the past when I needed a speedometer re-calibration for my 2005 and they were pretty decent. They charge $125 for a full systems check and diagnosis, and didn't charge any extra for the re-calibration. If they can give us some extra information on it, great, we'll aim in that direction. If not, no problem, we'll go for the filter and fluid and change it ourselves. We just don't wanna waste time on this repair since we've got a lot going on.

I'll let ya'll know how it goes. Thanks again!

Have faith in the forum members. We help each other. None of us will make dime if you follow our advice. Unless your diagnostic includes a chemical test of your tranny fluid, that test won't tell you what we are. It will tell you that your TC isn't locking and needs to be replaced.

 

[copper]

That makes sense. I believe both of you without a doubt. I just wasn't sure how deep these scanners will read into the engagement of the components. If it'll just tell them that bit of info about the TC not locking up, it sounds like it could be a wasted trip to the dealership. Any thoughts on the EGR and rich vs lean depending on the gear it's in? We saw someone's post in another forum about how the EGR will affect the coils and firing pressure(don't quote me, just trying to remember what it said of sorts) based on the gear the tranny is in, and the ratio/mixture would even out in the lower gears to where you wouldn't feel the shuttering as much. Not sure if it applied to this engine or not. It seemed reasonable and made sense to me when I read it, but I'm still leaning towards the fluid and filter since that's what the majority of people are saying.

 

[Fred Valdez]

quick question...when was the last time spark plugs were changed? I too had hesitation in over drive when the rpms were lower..I researched anything to do with transmission and found threads regarding tune ups and more specifically, changing out the plugs... I figured I'd rather it be the plugs than anything related to the tranny..swapped them out and my "tranny" hesitations disappeared...

 

[gixer2000]

quick question...when was the last time spark plugs were changed? I too had hesitation in over drive when the rpms were lower..I researched anything to do with transmission and found threads regarding tune ups and more specifically, changing out the plugs... I figured I'd rather it be the plugs than anything related to the tranny..swapped them out and my "tranny" hesitations disappeared...

I agree 100% and almost mentioned that but he said plugs and could were already done. Imo it's still worth looking into and probably the cause.

Misfires also wont always set a SES code so you'll need a scanner with Mode 6 to see all the misfires vs just the ones that set a code like most scanners show. I used Bluedriver and it work very well

Bluedriver.com

 

[copper]

We ordered a Bluedriver to diagnose it further for the misfiring that won't show up with regular code readers. We'll see what we can find. This is from FTE member Bluegrass regarding the shuttering from the EGR system:

A 402 code could be implicated but not a 401.
The shudder involves the EGR system when it is operating during that time.
A 402 code indicates the PCM diagnostics has detected a leak in the EGR tract into the intake when tested for flow during idle.
A faulty coil can react to this during cruise conditions as an excessively lean condition the coil can't fire on that cylinder.
The result is a shudder feeling from one cylinder that comes and goes with driving conditions.

To expand on this issue here is what happens to cause the misfire.
At cruise and low throttle, the EGR is called to opens.
This leans the air to fuel ratio as high as 22 to 1 lean.
If any cylinder's ignition can't fire the charge with hot enough voltage a misfire will occur at that time.
On a coil over plug ignition the usual fault is a coil with 'shorted' turns on it's winding.
The PCM detects the misfire and stores that info in program registers/memory as misfire counts.
If you force a down shift, the EGR closes and A/F ratio returns to normal levels in the 16 to 1 range or lower and is easier to ignite so you see the issue go away until the next time you enter the EGR operation.
It sometimes can get so bad that the coil generates enough interference on the harness that the PCM will stop processing any part of the program.
This turns into a violent jerking action until the PCM recovers it's normal program cycling.
I would advise you to use a good Scanner capable of looking at Ford's mode 6 and test 53. This test mode contains the misfire monitor counts for all the cylinders and should expose the offending cylinder.
The counts may show in Hexadecimal notation and can be converted to decimal with your computer using the calculator and conversion functions.