High RPM on highway then drops/less responsive (1 Viewer)

[Seymour Cruisers]

Tried searching around for similar problems on here and couldn't find the exact case. Sorry if this is a long explanation.

Essentially, everything sounds and feels fine until I get into high gear on the highway/50-55mph, but the tach shows a much higher rpm than normal. Usually when I'm hitting 75mph it shows 2200, but is now pushing 3k, and 60mph is 2200. This will last maybe about 15min, and then the needle will start to flicker, and then fully drop back down to normal. If I get down below 50 on the same drive, and then push back up it starts the process all over again.

Loss of power isn't noticeable until going up a hill or the on-ramp. Not getting any codes either. Spark plugs/Transmission/dist? If it helps, I can try and film what the cluster shows.

With the shops all busy and hearing similar problems somewhat similar to mine are harder to diagnose, any and all help is appreciated! I've got a 22 hour drive coming up in 2 weeks from GA to ND, so if anything just hoping nothing in this means my 80 will blow up

'95 1fz-fe. Stock height and tires.

 

[voodu3]

This info will help everyone help you.
Year of your truck
What engine
Any mods lift, bigger tires etc.

if you haven’t, download the FSM for your truck in the resources section. The troubleshooting in the FSM is super helpful diagnosing problems that pop up.

To your issue:

Does the O/D light ever flash on the dash?
If you push the o/d button on the shifter does it light up?
Have you done any work on the truck recently?

 

[Malleus]

Tried searching around for similar problems on here and couldn't find the exact case. Sorry if this is a long explanation.

Essentially, everything sounds and feels fine until I get into high gear on the highway/50-55mph, but the tach shows a much higher rpm than normal. Usually when I'm hitting 75mph it shows 2200, but is now pushing 3k, and 60mph is 2200. This will last maybe about 15min, and then the needle will start to flicker, and then fully drop back down to normal. If I get down below 50 on the same drive, and then push back up it starts the process all over again.

Loss of power isn't noticeable until going up a hill or the on-ramp. Not getting any codes either. Spark plugs/Transmission/dist? If it helps, I can try and film what the cluster shows.

With the shops all busy and hearing similar problems somewhat similar to mine are harder to diagnose, any and all help is appreciated! I've got a 22 hour drive coming up in 2 weeks from GA to ND, so if anything just hoping nothing in this means my 80 will blow up

Your lock up isn't. The torque converter is supposed to lock up at 53mph, give or take a few mph. The lockup test is to drive at a steady 53mph (±), and then increase the pedal pressure slightly. If the engine rpm increases, the TC hasn't locked. Pull out the service manual and check for transmission fault codes. You should have at least one.

Report back when you've found it/them. Put all the stuff @voodu3 suggested in your signature line, so you don't have to keep typing it, in response to everyone's questions.

 

[Seymour Cruisers]

This info will help everyone help you.
Year of your truck
What engine
Any mods lift, bigger tires etc.

if you haven’t, download the FSM for your truck in the resources section. The troubleshooting in the FSM is super helpful diagnosing problems that pop up.

To your issue:

Does the O/D light ever flash on the dash?
If you push the o/d button on the shifter does it light up?
Have you done any work on the truck recently?

Drove it last night, O/D on the cluster works correctly, but no I have not seen it flash on and off. In the past month or so I've replaced all the rotors and rear calipers, worked on front axle/birfs.

'95, No lift, 1fz-fe engine, stock tire size. Wish I had looked at the resources section when I first got the rig instead of buying the whole book lol. Guess it can't hurt to have on hand though.

 

[Seymour Cruisers]

Your lock up isn't. The torque converter is supposed to lock up at 53mph, give or take a few mph. The lockup test is to drive at a steady 53mph (±), and then increase the pedal pressure slightly. If the engine rpm increases, the TC hasn't locked. Pull out the service manual and check for transmission fault codes. You should have at least one.

Report back when you've found it/them. Put all the stuff @voodu3 suggested in your signature line, so you don't have to keep typing it, in response to everyone's questions.

On the drive last night, rpm didn't increase doing that test. Might be a stupid question, but since I was planning on replacing all the fluids anyways, do you think changing the trans fluid might help any? Honestly not sure the last time that was done and got the car in May and have driven it about 5k miles. Kind of put that off for other work since everything felt smooth at the time.

It could be my scanner isn't the best, so might have oreillys or someone take a look with theirs while I'm getting all the fluids today.

 

[voodu3]

Definitely check the transmission fluid per the FSM. It never hurts to replace fluids that you don’t know the history of.

 

[Malleus]

On the drive last night, rpm didn't increase doing that test. Might be a stupid question, but since I was planning on replacing all the fluids anyways, do you think changing the trans fluid might help any? Honestly not sure the last time that was done and got the car in May and have driven it about 5k miles. Kind of put that off for other work since everything felt smooth at the time.

It could be my scanner isn't the best, so might have oreillys or someone take a look with theirs while I'm getting all the fluids today.

Pull the dipstick. If the fluid isn't bright red, change it, but don't just drop the fluid in the pan. You can only get, at most, half of the fluid out using the drain plug, and that will take a couple of days.

If you use the fluid cooler line connection at the front of the truck, you can get the tranmission pump to pump out all the fluid while you pour new fluid in. This is the best, safest and quickest way to exchange the transmission fluid. This is the method I use. I run the tranmission until it's at operating temperature, then pull the plug and let it drain overnight. This speeds up the fluid replacement process by half. The whole operation should take no more than an hour, and that's if you've never done it before.

If the lock up solenoid is faulty, or at worst, the torque converter clutch has failed (which are two of the three root casuses of a lockup failure), this won't change anything, but it will improve the tranmission operation. You should change your fluid at least every two years, with normal driving (not primarily off road, stop and go [Uber], or in other harsh environments.

 

[Malleus]

FWIW, lock up only improves fuel economy and long term service life. In the short term, you can safely ignore it.

 

[Brindleboxer]

And per @jonheld from an earlier post:

There is an entire section regarding A442F troubleshooting and diagnosis starting on page AT-17 of the FSM. Just sayin'...