2001 Toyota 4runner Acceleration Issues

toyota
4runner

#1

When cruising down the highway my acceleration suddenly dies on me. Pressing the pedal to the floor does nothing for 5-10 seconds and suddenly I have acceleration back. It’s gotten to a point where it is dangerous to drive as I am just coasting along until it kicks back in.

This usually happens more in the summer than winter and is most noticeable when I am on a highway with rolling hills. My cruise control has no idea what to do when this happens and redlines the engine when it is able to get the throttle to respond. I sometimes notice the power cut too when I hit a bump hard or go around a sharp corner.

I’ve had a complete tuneup recently. New O2 sensor, MAF sensor, throttle body cleaning, air filter, spark plugs and it still goes haywire. I’ve even reset the system several times by leaving the battery off overnight and manually reset the TRAC system with no luck.

I’ve been all over the Internet trying to solve this issue for several years and so far it is just getting worse and worse. These fly-by-wire systems drive me nuts… Any ideas? Thanks.


#2

If it’s a fly-by-wire throttle body, there’s three components that can cause this.

The throttle pedal position sensor, the computer, or the electronic throttle body.

Tester


#3

Do your warning lights illuminate when the acceleration dies?
The comment quoted above almost makes it sound like you have an intermittent connection somewhere. Usually these type of intermittents are in the battery connections, sometimes a broken post internal to the battery.

Note that this is not a diagnosis. There’s insufficient information here to do a diagnosis. It’s simply a possibility to look into in the process of trying to diagnose this.


#4

Unfortunately the throttle body and TPS are all one unit so to replace either you have to replace both. I think it’s about $1,200 new plus labor. Maybe I’ll have to find one in the junkyard and have a mechanic install it. Thanks for letting me know. Hope it’s not the computer.


#5

No warning lights. Usually happens when I am on a straight hilly road. Rarely happens around corners or over bumps, but I have observed that sometimes but not always. Thanks!


#6

Hve you tried a new crankshaft position sensor or camshaft position sensor?


#7

My first thought on reading your post OP is that you may have a transmission problem. It sounds like it is slipping, which effectively disconnects the engine from the wheels. The engine rpms can soar to redline, but the power never makes it to the wheels. Do you have an automatic or manual tranny?


#8

A junkyard part may have the same problem and you will never know it because it will still be there. I notice you only mentioned 2 of the 3 things @Tester mentioned. The cheapest and easiest to replace is the throttle pedal sensor. Why not start there? Replace it and see.


#9

UPDATE: replaced the throttle body. Found a used one on eBay for $200. Compared the one in my vehicle to the one I bought when they were both out of the car and the one from my vehicle did not operate as smoothly as the one I bought. I think the motor/servo that opens the butterfly valve was dying on the old one. After replacing I notice an immediate improvement in acceleration, idle and have not had the acceleration die on me once yet. Fingers crossed, this may have solved it. Thanks everyone for their input.


#10

What’s your explanation for the engine rpms red-lining OP? Do you think the throttle position mechanism was sticking in the low rpm position then suddenly becoming unstuck, and rebounding to full blast? I wouldn’t have guessed a failing throttle body would normally fail in that manner. There’s usually some kind of fail safe in the design that prevents that from happening.