Weird throttle/acceleration hesitation

R

rwh963

Member
model: 2007 sr5 v6 4wd 229k miles

Problem: started occurring several weeks ago. the ability to access;erate will just drop out, then return after a few seconds, then maybe repeat. in that moment, i can floor it without immediate response. if i do that, in a moment i can feel it kick in and zoom.

the feeling is as if i am removing my foot from the gas pedal. it is chronic enough that it occurs multiple times each day.

Solutions: i've research. i added a techron concentrate through a tank. no improvement. purchased MAF and throttle body cleaner. cleaned MAF, no difference. cleaned the throttle body from the air intake side. paid attention to both sides of the butterfly, and esp. the edge that it rests on. got out some carbon. at first i though it made a big difference. then after a few days the problem emerged again.

i've heard of some replacing the whole throttle body. is there maintenance to be done between the pedal and the fuel/air intakes?
 
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Testing and/or replacing the throttle position sensor (Or whatever they call it on these) seems to be the best starting place to me before you replace anything.

I've seen a few threads about throttle bodies recently though, but start with the easy and cheap options first...
 
Do you have any ABS/Brake codes/lights when this happens? I would also test the throttle position sensor with a meter to see if it's just that.
 
SurferUK said:
Testing and/or replacing the throttle position sensor (Or whatever they call it on these) seems to be the best starting place to me before you replace anything.

I've seen a few threads about throttle bodies recently though, but start with the easy and cheap options first...
Click to expand...

Testing is your only option for checking the throttle position sensor, on 4Th Gen T4Rs the sensor is made into the throttle body and can't be replaced unless you replace the entire throttle body.
 
gm350reratliff said:
Do you have any ABS/Brake codes/lights when this happens? I would also test the throttle position sensor with a meter to see if it's just that.
Click to expand...

well, that's a loaded question! i have at least one thread regarding by brake lights being on all the time when the engine is on. i also have vac off/vsc trac lights on all the time. no abs light.
 
partsgeek lists a new Aisin throttle body for about $175. worth considering. also ran across some reset instructions. i'll try that first.
 
AuSeeker said:
Testing is your only option for checking the throttle position sensor, on 4Th Gen T4Rs the sensor is made into the throttle body and can't be replaced unless you replace the entire throttle body.
Click to expand...

Interesting, I assumed it was drive-by-wire with the throttle being a glorified potentiometer. So there's a cable to the throttle body in the engine bay?
 
rwh963 said:
well, that's a loaded question! i have at least one thread regarding by brake lights being on all the time when the engine is on. i also have vac off/vsc trac lights on all the time. no abs light.
Click to expand...

Yeah I thought so. I'm wondering if the VSC/ABS is intermittently seeing something and cutting the throttle or if you have a separate issue now.
 
rwh963 said:
model: 2007 sr5 v6 4wd 229k miles

Problem: started occurring several weeks ago. the ability to access;erate will just drop out, then return after a few seconds, then maybe repeat. in that moment, i can floor it without immediate response. if i do that, in a moment i can feel it kick in and zoom.

the feeling is as if i am removing my foot from the gas pedal. it is chronic enough that it occurs multiple times each day.

Solutions: i've research. i added a techron concentrate through a tank. no improvement. purchased MAF and throttle body cleaner. cleaned MAF, no difference. cleaned the throttle body from the air intake side. paid attention to both sides of the butterfly, and esp. the edge that it rests on. got out some carbon. at first i though it made a big difference. then after a few days the problem emerged again.

i've heard of some replacing the whole throttle body. is there maintenance to be done between the pedal and the fuel/air intakes?
Click to expand...

I keep a close eye out for threads talking about expensive issues I've dealt with.

This might be the first post I've seen in a very long time talking about the V6 throttle body (TB). The V8 TB has some flaw that makes it do some crazy things, though; which other threads lately are talking about.

Does this have anything to do with your speed/braking? What you describe is something that the A750 (5 speed) has been known to do when cruising, then suddenly brake to below 10MPH. It's an issue with one of the solenoids, the behaviour feels like the truck "forgets" to go back into first for a bit. My truck would like to do an AWD burnout if I worked the throttle too hard while "out of gear"; she'd rev up, and kick into gear while the engine is spinning fast, and hook up and go. Feels like getting rear ended.

Your truck is an '07, so it could be that, if the problem comes around when you're braking to a slow speed.

Hope that helps.

EDIT: I found a post/thread that talks about the issues in greater detail: https://www.toyota-4runner.org/3594255-post25.html
 
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if anyone has a couple of hours to spare and wants to dig deep into what may be a connected problem, please find a comfortable chair and open my thread: Brake lights constantly on?

in terms of this hesitation, i mentioned elsewhere that in investigating the above threads issue, i tested the cruise control for functionality. having been involved with this vehicle since new, i don't believe the cruise had ever been used. it seemed to do well open the highway test. however, sometime after that, this hesitation issue emerged. call me crazy, but weird coincidence. haven't tried cruise since.

also, no CEL light, which i feel is strange, and yet the behavior is kind of like letting off the pedal and then stepping on it. maybe wouldn't trigger a CEL.
 
SurferUK said:
Interesting, I assumed it was drive-by-wire with the throttle being a glorified potentiometer. So there's a cable to the throttle body in the engine bay?
Click to expand...

It is drive by wire, no cable, but the throttle position sensor is not a removable/replaceable part it is build into the throttle body.

On 3rd Gens T4Rs the sensor is removable/replaceable, but not on 4th Gens T4Rs.
 
funny thing, i just did a couple of days of highway driving, which i rarely need to do, and it drove fine without any noticeable hesitation episodes.
 
small update. did another highway run. drives and accelerates normal on the highway. never noticed a single hesitation/drop in rpm. so, so far only experiencing this issue on local roads/local speeds.
 
here's a thought: could a fill up of bad fuel be behind this? i imagine it would linger for while as it is cycled completely out of the fuel system.
 
had tro do a 50 mile RT highway run. 4runner drove fine on the highway. got back, hesitations on local roads. hhmmm.
 
ok, anyone want to chime in? several days ago i topped up my tank, and have kept it about 3/4 full. zero hesitation. during the long period of hesitation, i bet my tank was always below 1/2, if not running between 1/4 and low light. correlation?
 
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after running the tank below 1/4 twice, and now topping off again, zero hesitations. just did 100 miles highway, nothing. nothing locally as well.

could be the MAF and throttle cleaning i did earlier kicking in as well. i'll be happy if i don't have to spend on replacing the pump.
 
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