Hi all! I did my best to search this forum first and did find some notes on transmission slips but they were not identical and not very helpful.

I have a '97 F150 4x4 with the 5.4L engine and automatic transmission. The tranny's been slipping on and off for a couple of years. It started when it was hot outside, I had been driving a long ways, and I was trompin' on the gas to pass someone. Still, the slips were rare. As it got worse during the hot summer months, I just minimized my long-distance travels.

I recently took it to a transmission mechanic. Like some of the feedback to posts in here, he felt it was a problem with the engine - because we had a bad EGR valve signal on the computer. (We still flushed the fluid. I later replaced the EGR and the DPFE. Another mechanic went through everything, replaced some valves that had something to do with the EGR, and feels the engine is 100% (and it runs very, very smooth). For those that will bring it up - I have replaced all of the coils (though it's been a few years). Having actually replaced some numerous times over the years, I can feel when one is bad (of course, the 'check engine' light helps as well). Lastly, we've replaced all bulbs in the dash so they are all working as well. Also, the transmission is not leaking. The computer system is giving us no errors/throwing codes.

After a couple of weeks, I happened to drive the truck a long distance one day and it started slipping. It got bad enough that it was slipping every time going from first to second gear. It would usually engage as I took my foot off the gas. Since then, because I haven't driven long distances, I have not had a problem.

Any suggestions? The transmission mechanic thinks it's still an engine issue. He also mentioned a mechanical/electrical switch system on the side of the transmission (?). Give me a list of things to look at.

 

sorry to hear that, i know that on my first car (a 1992 chevy 1500) when its tranny started slipping, which got really bad without much of a worning, my dad and i put some sort of fluid that was supposed to be a short term fix in the tranny fluid and it stopped slipping for a while. I forgot the the name but we picked it up from auto zone. i know thats only a short term fix but if you find the fluid that i'm talking about it should get you to where you can drive your truck without dealing with the slipping

 

The Issue you describe sounds like a 'Modulator Valve' .I am not sure on newer models. I dealt with the same issues on 60,70 & 80's Model Vehicle..

As far as a Good Transmission Additive - I recommend 'Lucas' or 'CarGo'. I've had excellent results from both..

 

The only positive reference to slipping was shifts from first to second.
Is this what your referencing?
If yes, the trans need service internally.
The computer only deals with the electrical operations of the solenoids, the converter lockup.
It cannot tell anything about the physical operation within the tranmmission.
You have no codes for engine or trans so you have to deal with the trans mechanics.
Could be as simple as a broken spring in the valve body.
Electric controlled transmissions have no modulators.
At the age and mileage things begin to wear.
You can't set and talk it into a fix.
Some body has to get in and look for the issue.
Good luck

 

Thanks, Bluegrass. That's what I was thinking... we need to look inside. Well, that and I need a different transmission mechanic! HA-HA-HA!

 

I am not sure on newer models.

 

97-11-11***TRANSMISSION - 4R70W - ERRATIC OR PROLONGED 1-2 SHIFT***TRANSMISSION - AODE - ERRATIC OR PROLONGED 1-2 SHIFT


97-13-23***TRANSMISSION - E4OD - INCORRECT SEPARATOR PLATE - 4X4 VEHICLES BUILT FROM 4/18/97 THROUGH 4/21/97 ***TRANSMISSION - E4OD - SLIP/BUMP 1-2 UPSHIFTS - 4X4 VEHICLES BUILT FROM 4/18/97 THROUGH 4/21/97


Check the following TSB's they may apply to your vehicle.

 

Thanks for the priceless input, simsjackop.

Lime1GT - I greatly appreciate it and am following up via those links. That's the info I was looking for! THANK YOU!!!