4wd surging and bucking under load??

In 2wd my throttle is flawless. I shift to 4wd and as soon as I accelerate the rpms jump all over and I am bucking all over. Almost like I am smashing the gas pedal on and off. Put it in neutral and all is normal. Seems like fuel is being cut. However I suffer none of these symptoms in 2wd. ?? Any thoughts.

 

front universal joints and or front wheel bearings bad?
possible bad transferase -issues?
front driveshaft issues bent ect..?
the dog you ran over could be stuck in there.
(ha ha like my joke)?
I seen cats falling out a car once.
you can take it to a shop and ask for estimate then fix it yourself.

 

are your tires all the same diameter?? within 1/4 inch of each other?? new rears worn fronts? they need to be all the same

 

Thanks for all the responses. Back in Alaska and I put the runner in storage. Def not any driveline or tire issues. It’s something electrical messing with the ecu when the runner light is engaged. Will be looking into it again in Nov.

 

it sounds like a TPS issue.
my car had bucking jerking at 40 mph do to the TPS.
check the TPS first (throttle position sensor ), then go from there.
you might have an engine code that can help.

 

90% its the TPS sensor

 

1. Car won’t accelerate, lacks power when accelerating, or accelerates itself
It may feel as though the car simply doesn't accelerate as it should. It may accelerate smoothly, but lack power. On the flip side, it may be that your car suddenly speeds up while you’re driving, even if you haven’t pressed the accelerator. If these symptoms occur, there's a good chance you've got a problem with the TPS.

 

Will check out the tps. However it only happens in 4wd. Even if I disconnect the vacuum hoses and the 4wd does not engage. As soon as I put the transfer case lever in 4wd and drive it surges and stutters. Transfer case back to 2wd. All good. I will probably go the “add” delete route and disconnect the wire harness from the transfer case and call it good. Prob get some licking hubs as well. I really would like to figure it out though. Thanks for the feedback.

 

Oh. Shoot I forgot. It’s been a few months but I did replace the tps and calibrated it. Funny thing though if I disconnect my tps and the vehicle goes into its backup mode the surging in 4wd goes away. 4wd is engaged and works perfectly. I literally through money at it all winter and can’t figure it out. My skills are limited as soon as it gets into the more electrical side and am pretty sure this is where the issue lies.

 

ok, could be the transfer indicator switch/sensor
test with ohm meter push=continuity free= no continuity

 

Thanks man. I will def. look into it. Unfortunately I can’t check till I get back to AZ in November. If u are still actively on this site then I will totally hit you up with some more info. Right now I just found out that my 3rd gen up here in AK has a rusted out rear diff.. so I can’t seem to find any rear axle housings in the state of Alaska either. Thanks again. On to other headaches. I guess I can’t complain seeing that I have barely put any maintenance on it in 100k miles. She’s totally sound otherwise though.

 

put a vacuum gauge on it and see if it drops to,
check for vacuum leaks.
the tool is only 9 bucks, and gives you a wealth of information.
temp. sensor should be changed often, as the computer uses/relies on that info a great deal.

 

oh, check the linkage to.
mine went out and in drive it was shifting in and out of gear, I was in-between gears, but the lever was on drive.

auto 4speed.

 

Got a 2008 4Runner 4.7L V8 That has a similar problem. Hesitating (like it’s running out of gas) while at higher speeds, acceleration, under load or up hill. Can anyone tell me where the TPS is on this model. I’ve wasted about 2 hrs searching the internet and YouTube with no luck. Seems the 4th Gen 4.7L is either a unicorn or it doesn’t have a TPS. would greatly appreciate any assist!