Transmission Clunk while accelerating

[coolmib]

My car is a 98 Toyota 4Runner SR5 4x4 with 170K miles.

This week I started to feel transmission clunks when accelerating strongly at higher speed (45 mph +). If I keep the gas paddle on from the very beginning low gear, it won't happen. It only happens when the paddle is released and the car coasts a while and re-accelerating. When it happens (i.e. the transmission clunks are felt and heard), I have to press the gas paddle very gently and accelerate slowly. The car can eventually still get to higher speed (70-85 MPH), but only after a gentle and careful paddling.

Please advise. Thank you.

 

[koulee]

I believe that it was acceptable that a little bit of shift shock is to be expected when accelerating fast.

 

[Sig220]

To be safe, you might want to keep an eye on your u-joints. Sometimes its very hard to tell when they have slack, but if they will "clunk" when accelerating after coasting you might want to replace them.

 

[Jon]

To be safe, you might want to keep an eye on your u-joints. Sometimes its very hard to tell when they have slack, but if they will "clunk" when accelerating after coasting you might want to replace them.

X2 Raise rear end and shake your drive shaft observing U-joints.

 

[brian2sun]

How long has it been since you lubed the driveshaft/u-joints?

 

[coolmib]

Latest development

In past several days, I've busy and did not take any actions on the car. Just been driving gently trying to avoid the problems.

Today, the "check engine" light was on. A code scan at Autozone found P0120.

They suggested to replace the TPS and I agreed for $53.

After changing the new TPS, the check engine light is gone, but the acceleration stutter still persists as before.

I checked the transmission fluid, it's clean and pink.

What else should I do?

 

[brian2sun]

We need some more history on your truck. When was the last time you did plugs and wires? Cleaned the throttle body (and IAC/MAF sensor along with it)? It's a 3.4L, right? LOL, and please don't call the 4runner a car, it's a truck dang it! That may be why it's stumbling right there, haha. It's pissed.

 

[coolmib]

ok, ok, my 3.4 V6 truck, not car :thanks:

In my memory, I have not done any dealership service/maintenance after 100K miles (or past 7-8 years), except I do very regular oil change at Jiffy Lube for every 3000 miles.

 

[coolmib]

So today I changed air filter, and cleaned the throttle body and the MAF sensors. The acceleration stuttering problems persisted, even though the code scan showing a "pass".

I was going to change a new MAF sensor, but the guy at AutoZone said it can't be MAF because no codes are showing.

Another thing I tried was to drive with cruise control on. Same symptoms.

I am clueless now :spider:...please help !!!

 

[manhunter]

I suggest having the ECU and actuator assembly checked out. It may not be relaying the right message to your transfer case or transmission and it is trying to engage in 4wd when you are not mechanically doing so. If you let it go further without being checked, it may engage it in 4wd without you knowing it, and do much more damage. Does your 4wd indicator lights on the cluster work, and if so, are they blinking or anything?