Time to chime in... Tacoma "Lurching" Update

This is from the more efficient torque converters in use now to improve MPG. a little change in idle speed (like when A/C kick in) will cause a "lurch" It's no big deal and it's normal. I'd sooner have the better mileage than a super smooth transmission.
As for it doing this in a stick, push the clutch pedal harder.

 

Ok here's something to think about that I noted after starting this post. I wonder if the "bump" people are feeling when coming to a stop is actually axle wrap and the axle springing back into place. So many have complained about soft rear springs that I wonder if that combined with harder stops contributes to the bump?? .. Plausable?


Hmm.. maybe time for another thread

 

I would say mine is most definately related to the AC since it only does it when the compressor is on. and i agree with Janster, its more of a bump than an actual surge

 

have the lurch with A/C off too, keep looking in my mirror each time thinking I was just rear-ended

 

^Are you sure that the dial is in the "Off" position and not on a setting like "defrost"?

 

Yeah, this thread is one of the reasons why I don't ever buy automatics, cause they suck ass

 

the "bump" feeling that you guys have is air in the slip yoke of the drive shaft. Most service shops don't properly lubricate the driveshafts when they perform an oil change. I know it may sound silly, but this is what probably 99% of your problems are. I have been fixing this problem on tacomas and 4Runners for years. Once the shaft has been improperly serviced for a while the slip yoke will get completely dry and cause and air pocket. When you come to a stop the shaft will slide out and then compress, but the air pocket will hold it out for a short while until it finally releases around the splines on the yoke. When it compresses it make that "bump" feeling like someone just rearended you. Once the slip yoke is dry though, it needs to be disassembled and packed with grease to fix the problem. There was a previous thread on this that I gave an explanation of how to DIY if you so wish. Hope this helps

http://www.tacomaworld.com/forum/technical-chat/5277-clunking-noise.html

 

So how do you explain the fact that it happens when the truck is new? Or, like in my case, when you only get it when the a/c is on? This is probably the 4th or 5th possible cause that I've seen on the forums. I'm not saying your explanation is flawed, I'm simply questioning whether or not this is the actual cause.

 

that is why I said that it was probably 99% of you who are experiencing this type of issue. As stated in an earlier post, the A/C issue is most likely due to a fluctuation in idle speed which would replicate you stepping on the gas. When you come to a stop with the A/C switch off, step on the brake pedal a little harder than you normally do, then turn the A/C on and see if that cures your issue.

 

also, to explain the issue of it happening on a new vehicle. I can personally attest to it happening on a new vehicle. When I bought my 07 4Runner, I noticed this issue occuring at 150 miles. I performed the fix for it and have never had it happen again, since I have been maintaining the vehicle. so.....chalk it up to improper assembly by Toyota, they are good, but they are not always perfect. As I said before, I am a Toyota Master Tech and have been for about 10 years. This problem is a common one, that I have been fixing for many years.

 

OK, then I'll bring this up with my local service dept. Thanks for the info.

 

I think we're talking about a couple different lurches.....

I've got a Scangauge and I've been watching the rpm's while I'm stopped.

When I feel that infamous 'bump' - the rpm's go from around 500 to up to 700 when it happens. I know its related to the computer programming and whatever else the system is doing and why..... I've been getting it under normal driving, no A/C running, no blowers, just my radio. I've had previous vehicles do the same so I don't worry about it. Just having fun trying to watch it and learn from it.

 

I've sorta noticed the RPM change but I've only had it happen when I've come to a hard stop like coming off a freeway offramp and hitting the brakes har. I've always attributed it to the fact I drive an automatic and that it's probably at the last downshift before the complete stop.... that and a bit of axle wrap to cause the bump part of the scenario. If I come to a "slow and controlled stop " then I don't seem to have anything at all and the truck drives "normal". That was one of the premisses for my origional thread post... how much of the symptoms are due to the way someone drives and how much is an actual problem with the truck. If you've never experienced axle wrap for one and you then drive a truck for the first time it might be a little unnerving until you realze what it is. Can't say that's actually the cause here but it's one thing someone driving a truck for the first time might experience and then say there was a "defect".

 

I always come to a slower stop.....and that 'bump' takes a good 3 seconds or longer before I feel it occuring after a complete stop. It's long enough that I sit and watch the scangauge and look up at the stop light to make sure it's not green yet. and look back down again at the scangauge. My truck has been doing it more often now than previously (7,000 miles). There could be a whole host of reasons why it does it (or not).

If you're experiencing a delay after stopping (like I am) - then it won't be axle wrap. Axle wrap & driveline slop will occur almost immediately after stopping and the entire suspension & driveline is released of the torque.

 

Call me dumb but how does the suspension and driveline release all that torque after stopping on an automatic transmission if you're still in drive and your foot is hard on the brake? I would think that to release all that pent up energy that something has to give somewhere right? Slightly letting up your foot on the break.. could it in fact cause a movement forward as the energy is released??? .. Just curious not jerking your chain. I'm sure with a manual transmission just putting the clutch in or putting it in neutral would release the driveline energy. Different though with an automatic right??

 

Automatic or Manual ...doesnt' matter.
There's a big difference between the torque that is applied when moving versus torque that still exists while stopped. BIG difference.

As soon as you step on the gas, there's a hell-of-a-lot more torque on that driveline and suspension then when you're sitting at a stop sign.

 

I read comments about sudden acceleration on mycarstats.com and some of the experiences related were far more serious than the discussion currently being held here. It seemed to be focused on the 07 Tacoma. Toyota said they don't have any knowledge about the problem, but they will investigate. We shall see. I 've never had any experience with sudden acceleration with my 07 Tacoma Prerunner, but it does cause some concern. I suggest the others should take the time to do a little research on the subject.

 

^Did you seriously join an internet forum using your personal email address?

Awesome.

BTW, ever think that the "more serious problems" could simply be a loose nut behind the wheel? Do a search and check out the vid of the goofball with the manual trans saying he has this problem. Yup, you need to do some research yourself.

 

i think is has something to so with the brake system. it happened on my 07 4x2 while i was coasting to a stop. the AC was off, so was the defrost and the stick was in neutral.
the brake assist system monitors the amount of force on the brake pedal when you apply it. it then, if needed, applies extra force in order to stop in time. it sounds more like a glitch in the computer that controls the system.

also, do you think it just could be that the brake pump isnt as strong as it should be and cant move enough fluid out of the resivoir?

 

when i had my 06 trd ac at just starting it and trying to put it in gear it wanted to go with the break pedal all the way down. But think that he is exagerating