Double cab v6 "bumps" at traffic lights

Oh, I have the double cab with the towing package as well. Incase it is isolated to that specific set up.

 

NHTSA has been looking into this for years. Until your truck uncontrollably takes off and runs off the road and possibly kills you, you won't get anywhere.

Just google 'Tacoma Lurch' and you'll see.


This is a very old issue and we're beating a dead horse here.

 

This is not axle wrap.
I happens after you come to a complete stop and have been stopped for ~10 seconds or so while still holding the brake. The "bump" feeling comes and the truck will lurch forward slightly, a feeling as though the car behind you has just bumped into you. I find it incredibly hard to believe that this is the A/C compressor kicking on.

Again, this is not a scenario that happens as you're slowing to a stop or after you have just stopped. It happens after you have established a stop for a considerable amount of time.
'13 DC auto here also. I had an '06 that I believe did the same thing, so I'm fairly certain this is not a new issue.

 

The compression kicking on jumps your rpm's, causing more power to the wheels, ultimately leading to the brakes not holding the vehicle still. Think about it. You push your brakes to just barely hold the vehicle at 900 rpm's. the compressor kicks in causing the vehicle to jump up to, lets say, 1000 rpm's. this would cause the truck to slightly "lurch" forward and you would counteract by pressing harder on the brakes.

Not rocket science

 

This

 

With how many other manufactures forums I have seen this on, not worried about it. It is not only isolated to Toyota.

 

My FJ use to do the same thing. Toyota has a TSB on it for the FJs, dealer replaced my drive shaft with new one, took care of issue. I didn't know the tacos had same problem still waiting on my '13 to show up.

 

Maybe it is, in fact, rocket science because it still happens with the A/C off (and defroster). How do you explain that, Detective?

I get the mechanics behind a compressor kicking on and a rise in RPMs but I find it hard to believe that it would cause such a surge as to make the driver feel as though he was just assholed by the vehicle behind him at a light. Especially, like I said, when the A/C and defroster are not in operation. Even if that were the case, a sudden 100 RPM rise is insignificant and would not give the sensation of having just been in a collision.

 

You also have an engine cooling fan that kicks on when you come to a stop, which will raise rpm's and cause the exact same feeling. Axle wrap also cause this same feeling. The force of the axle settling back in place will lurch the vehicle

 

Both my Tacoma and 4runner do this. There is nothing wrong with your truck. I worried about it too until I joined this site. No big deal. Both trucks have over 100k and still going strong.....

 

I rarely use my ac and my engine is constantly changing rpm's at idle. Everyone's does. I have a manual though so I don't feel the effects as you AT guys do

 

not to mention the ac will also still cycle even while off if either defrost setting is selected

 

Detective_Dan is spot on IMO. A real sleuth

 

And thanks lol. At least some people can read and comprehend

 

In my opinion, it feels like the brakes are releasing and reapplying.
Maybe an idiosynchracy of having ABS with drum brakes.

 

My Co-workers 2011 4runner does it, it sounds like the torque converter unlocking or locking. (happens with A/C and defrost off) It's extremely hard to notice, but it's there.

 

answer one question and we'll stop talking A/C

Do you have the A/C on OR is the hvac control set to either of the 2 defrost settings?

 

just like in all other vehicles ive owned. THis is a much more stronger sensation - As I said earlier I thought someone bumped me from behind. 60K miles and never did it until a few weeks ago. I would not find it acceptable in any vehicle - I like the truck ( have owed fords, chevys, and a tundra) but the lurch is bad. Also, dad has 09 - same truck - 120k miles - never done it. Thanks for all the ideas, think I will start by checking all hardware and changing trans fluid.

 

My 12 SR5 DC bumps too, I just live with it. I, also, thought I was rearended when it first happened.

As for dective dan's theory, I would expect the "bump" to happen a lot more frequently than it does to me if that were the case. I run my AC and defrost very often and it only happens once or twice a week.

Also, tonight on the way home while at stop lights I kept a constant eye on my tach. Every time the compressor cycled my RPM's would jump up 100 to 200 and I never felt the slightest twitch. If the "bump" is due to RPM surge I would think they would have to jump 500 or more which I don't see happening.

I will be in the truck for 11+ hours this weekend so I will try to keep an eye on the tach when I am at red lights.