Hey all! I have a 2005 F150 5.4l Triton 2WD Super Cab Flareside w/ 4R75E trans (trans code "B"). 189,000 mi and some change. I was driving this truck an average all about a hundred miles a day back and forth to work, on average reaching speeds a 45 to 50 miles an hour but a lot of start and stops at lights and stop signs Etc. But also reaching speeds of 70 miles an hour when I used the expressway which wasn't very often. Anyhow I never seem to have a problem with shifting or slipping but every now and then that would be a little jerk or shutter on acceleration and it seemed to be that it was trying to find the gear that it needed to be in. I never really thought much about it until one particular day I started the truck up let it warm and then took off. I reach a speed of about 55 mph then I had to come to a sudden slow down to about 30 miles per hour and very quickly after that to almost a complete stop. As I begin to accelerate to pick up speed once again I noticed that the engine was revving but I didn't seem to be picking up speed. I made it about another mile up an incline and then decided to pull over to see what the problem was. I check transmission fluid it was in the good hash mark area , I checked fuses nothing seemed to be blown except the OBD2 port fuse which was #41 in my fuse box under the kick panel on the passenger side. I made it back to my local auto parts store and had them run the scanner on it and it came back p0720 which suggests the VOSS or vehicle output speed sensor. I bought a new speed sensor from that auto parts store which cost me $52 USD (I later found the same one for $15 USD) . I installed the new sensor reconnected the battery started the truck let it warm took it for a test drive and straight out of the driveway it was doing the same thing. I was actually able to return the part and spent hours and hours and hours looking through wiring Etc. Eventually I bought a scanner for myself and ran the test on it and it came back with the same code along with a couple of others , so again I have ordered a new sensor in hopes that I didn't do something right the first time. Should I clear the codes before I take it for a test drive or should I let the computer clear the code after I drive it. this truck is driving me nuts trying to figure this out and I really need it for work I'm just wondering if I'm wasting my time and could it be a transmission problem. Thanks in advance for any advice or recommendations. What I'm getting is the truck starts fine the engine idles fine when I put it in drive it seems to engage but then it doesn't go anywhere the engine revs but no movement at first but if I continue to step on the accelerator it eventually will go and I can actually drive down the street but at any time it goes into limp mode with the Trans fault message and the overdrive light flashing with the illuminated wrench. once I shut the truck off and then restart it I can go through the whole process again.

 

The 5.4L will do that bucking and shuttering under acceleration between 40-50MPH when the spark plugs need replacing. Change your spark plugs and that might fix the issue. When was the last time that was done on your engine?

 

I change the spark plugs back in November of 2019 I did not change the COP's. I was doing some reading earlier and I read that sometimes a faulty coil can cause problems in the wiring to the PCM causing it to read a false signal from the OSS. I'm going to go out tomorrow in the daylight and see if there is any problem with any of my coils, maybe a crack or split that is visible.

 

with nearly 200K miles .. its time for new boots and springs at least... what brand plugs were installed? if they are not motorcraft... replace them.

 

I used E3.70 Diamondfire plugs, they had a 3 yrs wrnty for $12 a piece I thought I couldn't go wrong. I did the job myself, no problem with breakage but these also have a guarantee not to break off. I have been told since just recently by another that I should have used motorcraft. Actually he told me to use motorcraft everything when I could. Some of it's some pricey stuff. Haha. I've been thinking if i cant figure this problem out with the trans or whatever is throwing this code, i may have to sell her. Its going to break my heart but the wallet will be happy. I also just put new brakes and rotors all the way around as well as tires just before she crapped out on me.

 

Yeah, on our 5.4L's, you only use Motorcraft plugs.

 

Motorcraft plugs are not $12 ea. use SP546 only and buy some new boots and springs.

 

Pull the Mode 06 data to see if you have any misfires and if o, which cylinder its coming from.

I personally would do this b4 tampering with the COP'S unless, you plan to change them all out anyway.

You mentioned one code "along with others " but did not list them in your message. Having all the information available is crucial for establishing the most effective diagnostic procedure.

I would record all the current codes,, clear them,, then see which are recurring. Then report your findings.

That way, each of us on the forum can provide you with the best information based on each of our own experiences and knowledge base.

Thanks