Hi everyone. I am the owner of a 08 expedition king ranch 5.4L V8 6-speed that I purchased recently at a dealership. The pervious owner had driven all 225k highway miles and was the original owner.

HERE WAS MY PROBLEM AND HERES HOW I FIXED IT:

Within a week of owning this vehicle I noticed that it would stutter at around 35-55 mph at 1400-1500 RPM. I would have to be below this load or above for it to stop. It shifted great and drove amazing other than this. It would happen more as the car got warmed up after driven a couple of hours. The feeling when it stuttered was as if I was going over rumble strips and made a similar but grinding sound. To counter this from happening I would turn overdrive OFF when driving under 60mph. Which would completely stop this issue. Of course gas mileage plummeted due to running at a high RPM.

So my first guess was that it was a misfire. I took the car to a local shop and had them do a full diagnostics test. Which included revving the car for a min straight and whichever else they do. It turned out that the misfires logged on the computer were very low and misfiring was out of the question. I went on amazon and purchased a set of Performance Coil-on-Plugs (COP’s) they were the yellow and black ones and ran me about $80. After installation the problem persisted though I saw a nice jump in throttle response and gas mileage. (I HIGHLY RECOMMEND GETTING NEW AFTERMARKET COP’S)

So a couple of months go by and the problem seems to be getting worse. Now it is happening more around 35-65 at 1400-1500 rpm. And to be honest I am getting fed up turning overdrive off and on, and running my expy at a high RPM. So I get to thinking... Okay so it’s not a misfire, it has to be a computer/tranny Issue. So I decide the other day to run my truck for an hour on the road, and go through all the gears and check the transmission fluid. After doing this, I pull in my driveway to find I don’t have a dipstick. The 08’s and up are sealed service only. I end up looking under my truck and notice a 19mm bolt on the transmission. After doing research this is actually the dip stick. Unfortunately I did not have a 19mm box end. So I decide to take it to a local transmission specialist. Just some good country mechanics that have very high ratings online. He looks at it for a day and drives it as well and let’s me know he felt it alittle but his employee felt the shutter a lot. He was very puzzled to what it may be (surprisingly) but he did inform me it HAD to be some sort of torque converter issue. I asked him to check the fluid and see how it looked and give me a call back.

So he did, and he said it looked a little brown. He did say that tranny flushes are not super common to do on vehicles and usually the fluid last the lifetime of the engine. Especially on newer cars. So I decided to have him drop the tranny pan. Some research told me about this shutter and how the c-clips on the solenoid can break off and get stuck in the valve body.

I figured when he dropped the pan, half of the transmission fluid would drain out anyways. So I went ahead and told him replace the fluid and brought him some “LUBE GUARD shutter fix” - which comes in a little red tube for about $6 at an auto parts store. I brought him 2 tubes and he told me he would have it done in a couple of hours.

I go to pickup the truck that afternoon and he said his employee drove it about 15 miles (since he felt it more) and he did not feel it at all. It ran me about $320 for the flush, fluid, and labor. He also changed the filter. He did let me know he saw very very little metal in the pan (especially for 235k miles at this point)

I am posting this 2 weeks later with over a 1000 miles in since the fix. I am so relieved to have this tranny issue fixed as it has been very puzzling and frustrating. The truck drives awesome now and sits at that 1400-1500 RPM mark at ease.

I am uncertain if it was the new fluid, or the additive. All I know is the problem is fixed. The old fluid could have lost its properties being so old, and not lubricated the transmission like it is supposed to, in turn causing the shutter.

I decided to write this post for all if you experiencing the same issue, as there is little information online with the 5.4l shutters, misfires, etc...

I would recommend diagnosing a similar issue in this order:

1-Check COP connections
2-Get a diagnosis of your whole system for misfires
Replace COPS anyways (performance COPS make a world of difference in driving)
3-If you have an overdrive issue and it goes away with turning overdrive off, check the tranny fluid.
4- if tranny fluid is BAD, consider a flush and filter change with the “instant shutter fix” additive and if your fluid is GOOD add the additive to your fluid and see if it helps you.

5- if none of this works, you may need a rebuild. I estimate $600 MAX for testing and trying to fix this problem before doing a rebuild ($80 for Diagnostics test/free if you have a nice local shop, $80 for performance COPS/self install is not super difficult 5/10, $20 for additive, and finally $300 for fluid flush and filter change plus additive.

LET ME KNOW IF YOU HAVE ANY QUESTIONS OR EMAIL ME AT grayson@armstrongtransport.con