I have a 99 F-150, 5.4 and I have been having what I think is the start to a transmission problem. It has started when it downshifts or going into passing gear, when it starts to downshift the engine will increase RPMs and the trans will finally kick in but with a pretty hard klunk and then all seems fine. Under normal driving it seems to be fine, although I noticed tonight when I backed out of the drive it seemed to take longer to go into drive from reverse. Anyone out there have this problem and am I looking into a new trans in the future or hopefully just a bad sensor somewhere? Thanks in advance for any help.

 

Sounds like the pressure control sensor isn't working correctly. It's not seeing the pressures at the correct time, so it takes a while to operate. It could also be that the pressure isn't allowed to build up quickly enough, or sufficiently enough due to a defecting pressure regulator. Have you checked the fluid level and condition recently? When was the last time that the transmission was serviced? When a trans shifts hard, usually it's the computer playing it safe and allowing full engagement force to protect the transmission's internal components, such as the clutch discs. Softer engagement causes more slipping in these parts and accelerates wear, thus the reason for the stiffer shifts.

 

I would also check the fluid level mine made clunks when i would get off the gas and then back into it on a turn. since i added the fluid the clunk has gone away.

 

Thanks for the help, I haven't changed the fluid yet, and I guess I should it has 91,000 miles on it now. I know..... I should have done it a long time ago. I'll change the fluid and see if that helps, if not I will have the pressure sensor changed (or do it myself if I can find it) and see what happens. Thanks again.

 

Alittle late but somewhat related & curious as to the outcome.

My 98 F150 4x4 w/the 4.6 & AOD has always had a slow shift from D to R since day one. Was told it was normal and have lived w/it for 113K miles.
Also, I had the tranny serviced at the recommended time by the dealer and it seems that right after the fluid & filter change is when I noticed the shift from 1st to 2nd wasn't as crisp as the other shifts. I took it back and was told NTF. So I've lived with that also but since then and after talking with other folks, it seems many didn't recall any shifting or performance issues w/their trannys until they had the fluid & filter changed as a scheduled maintenance proceedure.
Now, what I do is when I check the tranny's fluid level I check for it's clarity & also smell it for a burnt smell. Once you've smell burnt hydro fluid you'll never forget it. So far the fluid is still clear as new and has no burnt smell to it so I've not had it changed since.

I've also been told that it's already too late to change the fluid once you've detected a tranny problem. In most cases, it'll either be a mechanical or electrical or vaccum device failure.

Good luck and I'm curious as to what the fix was.

Volfandt