Shudder / Shake when accelerating up steep hills from a stop

[luke87gt]

Hi guys,

I've had my 2006 4Runner V6 2wd for several weeks and encountered a strange problem today.

I was at a stop light on a steep hill. Light turned green and I applied the accelerator and the car shuddered violently several times before smoothing out and accelerating normally up the hill. Never felt that before.

I drove around for a few minutes and everything seemed fine. I then found another steep hill and came to a complete stop. Again I hit the accelerator and there it was again, violent shudder for a couple seconds before smoothing out and accelerating up the hill.

The car seems to only do this on steep hills under heavy load. It's only present when transitioning from a complete stop to movement. Once the car gets moving I've never felt any issues. In other words, once the car is moving it's all smooth.

Any ideas as to what it would be?

Thanks guys!

 

[ARunner]

How much gas in the tank and how steep are these hills? Steep enough to spin the tires? Wondering if it could be you're starving the fuel pump. If you have over a quarter tank of fuel I would think this unlikely. I had a car I could starve if on the track at just under a half tank. Just checking.

 

[luke87gt]

Tank was 3/4 full.

My initial thought was fuel filter... Then I read that these cars have in-tank "sock" type fuel filters which typically don't need replacing.

That's why I started to think possibly throttle position sensor or dirty MAF.

 

[gm350reratliff]

I would start by checking the transmission fluid level and possibly doing a full flush with the proper Toyota fluid. Second, I would check all the rear control arms and make sure the axle housing isn't trying to rotate causing a driveline shudder. I would also go over the engine mounts and transmission mount, make sure they are in good condition and the bolts are tight.

 

[luke87gt]

Thanks for the reply.

I will start off with the following (chances are these items have never been replaced/cleaned):

- Change spark plugs – I ordered a set of Denso OEM copper plugs for $3 each
- Clean MAF/TB
- Change transmission fluid and ensure level is right

Also, thanks for the suggestion regarding the control arms and motor/engine mounts. I don’t think this is the case however as it feels like power is intermittently being lost… like the car can’t get out of its way for a second or two when hitting the gas up steep hills.

Since it’s cheap, I may swap the throttle position sensor which commonly causes problems that are similar to this.

Luke

 

[fullboogie]

With all the reported issues concerning the torque converter lockup acting whacky (e.g. rumble strip sensation), I have to wonder if all these threads about lack of power on takeoff are related. In other words, I've often wondered if the lockup feature is acting up at a dead stop and not coming unlocked, which would definitely feel like a loss of power. I've been chasing a problem for over a year that comes and goes intermittently, which I first thought was a spark plug problem. I really wonder now...

 

[ghs215]

that's the Hill Start Assist 'feature'....

(I could be wrong :happens

 

[ghs215]

try this....


go to a steep speedbump, get the front tire just about to the top (not all the way), and press the brake to stop. now, let go of the break pedal and it will want to roll back down the speed bump...

the Hill Start Assist should kick in once the truck thinks its going backwards while in drive....

is this what you experienced?

 

[luke87gt]

I think you are absolutely right with this being the Hill Assist Feature.

The reason I think so is that both times it's done this, there was a beep at the same time. The beep happens when the Hill Assist feature activates.

Ummm, based on how it feels I don't know how this can be thought of as a "feature" lol.

Please tell me there is a way to turn it off because I don't find it useful at all... unless I am not using it right.

Big thanks for chiming in as you put me on the right direction...

 

[ghs215]

I believe the 'feature' is the ABS engaging brakes by pulsating and keeping the 4runner from rolling down the hill..

It startled the Sh!t out of me the first time it happened to me...

 

[luke87gt]

I believe the 'feature' is the ABS engaging brakes by pulsating and keeping the 4runner from rolling down the hill..

It startled the Sh!t out of me the first time it happened to me...

When it first happened, my wife and I were startled and convinced that something malfunctioned given the beeping and the fact that this is a very primitive feature that is anything but smooth.

I'm wondering if I need to "learn" to use it. In other words, when the feature activates, should you be easy on the gas, hard on the gas, give more time between letting go of the brake and applying the gas, etc.

Also, I'm curious if there is a way to disable it? As I mentioned above, I'll play with it some more but i think I'd rather not have it if it's going to startle the S out of me when it activates.

 

[gm350reratliff]

With all the reported issues concerning the torque converter lockup acting whacky (e.g. rumble strip sensation), I have to wonder if all these threads about lack of power on takeoff are related. In other words, I've often wondered if the lockup feature is acting up at a dead stop and not coming unlocked, which would definitely feel like a loss of power. I've been chasing a problem for over a year that comes and goes intermittently, which I first thought was a spark plug problem. I really wonder now...

Possibly. I've seen that very thing happen on a few E40D and 4R100 Ford transmissions before. I would think you would get a code on the 4runner though.

 

[ret42]

I think you are absolutely right with this being the Hill Assist Feature.

The reason I think so is that both times it's done this, there was a beep at the same time. The beep happens when the Hill Assist feature activates.

Ummm, based on how it feels I don't know how this can be thought of as a "feature" lol.

Please tell me there is a way to turn it off because I don't find it useful at all... unless I am not using it right.

Big thanks for chiming in as you put me on the right direction...

It definitely becomes a feature when towing. I've only had it beep at me once, but there was no shuddering when I took off. The hill I was on must have just been on the threshold of the system engaging though, because I stop on that hill almost every day and it only engaged the one time. I don't know that the hills in "The Hill City" here are comparable to those in SF though.

As for disabling it, there's always a way to disable everything. I would bet it involves pulling a fuse or messing with the wiring though, and I suspect you would have a light permanently lit on your dash. The light alone would be reason enough for me to leave it, but then I'm not the one dealing with an earthquake every time I start from a stop, either.

 

[fullboogie]

Possibly. I've seen that very thing happen on a few E40D and 4R100 Ford transmissions before. I would think you would get a code on the 4runner though.

I would think so too, but I'm not convinced that our system (or that of any other manufacturer) is that sophisticated. I've had far too many other things fail or act up on other cars that did not throw a code. Who knows.