Torque Converter?

[4Runner4TW]

Maybe somebody can help me out..

Coasting down hill between 40-55mph the RPMs will drop and bounce back (no gas just coasting). When it does the the truck "drags" like it tried to down shift or engine brake. Today I clicked the OD off and it didn't do it. I leave for work soon and will try this again.

Also, while coasting at these speeds, when I press on the brake the RPMs drop and bounce back. Does any one see this as well? I just read on google that when you hit the brake the torque converter engages/disengages? (I can't remember now)

I originally though air or fuel problem. Maybe a vacuum leak. But now I'm thinking it could be worse. I've also put it into neutral to see if anything would happen and it didn't. Only seems to be around those speeds while coasting.

Anyone with TC or transmission experience can chime in? I have a 99 auto 4x4 with 208,100 miles.

 

[StreetCreeper]

Maybe somebody can help me out..

Coasting down hill between 40-55mph the RPMs will drop and bounce back (no gas just coasting). When it does the the truck "drags" like it tried to down shift or engine brake. Today I clicked the OD off and it didn't do it. I leave for work soon and will try this again.

Also, while coasting at these speeds, when I press on the brake the RPMs drop and bounce back. Does any one see this as well? I just read on google that when you hit the brake the torque converter engages/disengages? (I can't remember now)

I originally though air or fuel problem. Maybe a vacuum leak. But now I'm thinking it could be worse. I've also put it into neutral to see if anything would happen and it didn't. Only seems to be around those speeds while coasting.

Anyone with TC or transmission experience can chime in? I have a 99 auto 4x4 with 208,100 miles.

While my experience was different than yours, I had a TC lockup solenoid go out on me and I would experience a constantly locking/unlocking TC at freeway speeds. Very annoying when on a 1200 mile trip.

While maybe not your issue, it's something to consider at some point.

 

[4Runner4TW]

While experimenting a bit I realized that by clicking the OD off the RPMs rise and I feel the engine brake sensation. What I'm experiencing is the RPMs drop with the sensation. Not sure if that would rule out the transmission though. Just an observation and thought.

 

[amalik]

While my experience was different than yours, I had a TC lockup solenoid go out on me and I would experience a constantly locking/unlocking TC at freeway speeds. Very annoying when on a 1200 mile trip.

While maybe not your issue, it's something to consider at some point.

Doesn't the TC lock by design at some RMP and speed combo range? Yours was basically doing it *before* that threshold?

While experimenting a bit I realized that by clicking the OD off the RPMs rise and I feel the engine brake sensation. What I'm experiencing is the RPMs drop with the sensation. Not sure if that would rule out the transmission though. Just an observation and thought.

OD is like a 4th gear from my understanding. Not sure what you're reporting, but elevated RPM's with OD off at a high speed is normal. OD will limit your speed... so if you hit the gas with OD off above like 45-50MPH.... you will start getting high RPM but wont be able to go faster. People only mainly turn OD off while towing or climbing / descending passes.

 

[StreetCreeper]

Doesn't the TC lock by design at some RMP and speed combo range? Yours was basically doing it *before* that threshold?

At highway speeds when it should be locked up, it would instead keep dropping out of lockup then quickly lock again....over and over and over. Not fun with three kids in the truck and 400 miles from home.

 

[jgue467]

While experimenting a bit I realized that by clicking the OD off the RPMs rise and I feel the engine brake sensation. What I'm experiencing is the RPMs drop with the sensation. Not sure if that would rule out the transmission though. Just an observation and thought.

Sounds engine related to me not tranny. The tranny is simply feeling the effect of a poor running engine. Cleaned the MAF and IAC lately? What other tune-up stuff has it had done recently? :cowboy:

 

[4Runner4TW]

Sounds engine related to me not tranny. The tranny is simply feeling the effect of a poor running engine. Cleaned the MAF and IAC lately? What other tune-up stuff has it had done recently? :cowboy:

I clean the MAF and Throttle body every 15k. New plugs about. 20k ago. Wires are about 40k old.

I'm not sure about the IAC. Someone suggested the TPS as well. No engine codes.

 

[amalik]

I clean the MAF and Throttle body every 15k. New plugs about. 20k ago. Wires are about 40k old.

I'm not sure about the IAC. Someone suggested the TPS as well. No engine codes.

IAC is bolted onto the TB with 4 phillips screws.

Kinda sucks to have to go clean it now that you already did the TB.

if you apply 12v and ground to the connectors, you can open the valve on the IAC to clean it while it's separated from the TB. That's what I did a few weeks ago.

 

[amalik]

At highway speeds when it should be locked up, it would instead keep dropping out of lockup then quickly lock again....over and over and over. Not fun with three kids in the truck and 400 miles from home.

Ah so that's when you had to do all your shift solenoids and stuff job?

 

[StreetCreeper]

Ah so that's when you had to do all your shift solenoids and stuff job?

Yeah. It wasn't long after that that I started getting shift solenoid codes being thrown.

 

[3bears]

wonder if this is what is happening to mine....

yesterday driving to my sons ( 100 + miles at 60+mph) the revs would shoot up a bit and then back down. Like 2000 to 2200 , and I could feel it in the way it drove. At first I thought maybe my rear wheels had hydroplaned in the rain and snow melt..
As the drive progressed it began to do it more frequently.
turning the overdrive button on and off, it acted just like the problem, so I thought...ok....whats happening
if so, when it does it by itself the light does not come on saying od off

got to his house, no codes, fluid level right on. Full flush, filter, cooler less than 6k ago,

thought I might just do a quick drain and fill to see if anything ugly comes out before heading back to my home today
.....4.5 qts..right?

 

[3bears]

Yeah. It wasn't long after that that I started getting shift solenoid codes being thrown.

you have a link or write up on to how to replace if that's my issue ?

 

[4Runner4TW]

After some research it seems mine might be sensor related. Going to take the intake apart tomorrow and clean it all up. I'll see if this fixes the issue.

 

[Twisted Sid]

Seems like you and me have the same type of problem. I think its TPS related but I'm not 100% sure. I have changed the TPS and the harness plug but it still does the RPM drop sometimes. I get an occasional TPS code but if i move the harness around and clear the code, the problem seems to go away for a while.

 

[keeperofgoal]

wonder if this is what is happening to mine....

yesterday driving to my sons ( 100 + miles at 60+mph) the revs would shoot up a bit and then back down. Like 2000 to 2200 , and I could feel it in the way it drove. At first I thought maybe my rear wheels had hydroplaned in the rain and snow melt..
As the drive progressed it began to do it more frequently.
turning the overdrive button on and off, it acted just like the problem, so I thought...ok....whats happening
if so, when it does it by itself the light does not come on saying od off

got to his house, no codes, fluid level right on. Full flush, filter, cooler less than 6k ago,

thought I might just do a quick drain and fill to see if anything ugly comes out before heading back to my home today
.....4.5 qts..right?

After some research it seems mine might be sensor related. Going to take the intake apart tomorrow and clean it all up. I'll see if this fixes the issue.

sorry I gotta revive this thread cause im having the same problem. foot off gas drags down shoots back up, hit the brake drops rapidly then shoots back up, in neutral drops, jumps and drops all in one very rapid motion. did either of you ever find the culprit ? im convinced its either a damaged tc or a bad solenoid but im not getting any codes. kind of pissed.

 

[4Runner4TW]

Never found the culprit. Still does it to this day with 310,000 plus miles.

 

[phattyduck]

Never found the culprit. Still does it to this day with 310,000 plus miles.

Mine has done it for as long as I can remember, with two different transmissions (a '99 2WD trans and a '97 4WD trans). 4Runner was bought new by my dad and I have driven it on and off since new...

-Charlie

 

[This4RunnerIsMine]

Check the transmission cable on the throttle body.

I think it adjusts the pressure/slip for shifts. Mine was too tight which resulted in some weirdness in shifting. Setting it back proper made everything run better. Since you just worked on that part of the engine, could be something to check.