Vibes on hard acceleration

I took mine to the dealer for this issue when I was under the rear diff recall. They blamed it on the motor mount being bad, and that I abused the truck.... this was before the real abuse. I might believe that now, but have had 2 trusted mechanics look at since and it's not the motor mounts.

 

Means you left your 6 pack of beer on your roof again....

 

A moment of silence for the beer that will never have the opportunity to nourish nor lead to poor life choices.

 

Consider it sacrificial to all the lost/dead Tacomas to come before you.....

 

Used to do 1/4mile runs with my uncle, and built engines with him (I am familiar with power bands/variable valve timing). Not bragging or anything, just that I understand what it is

For example... A honda will pull, then pull harder. This is assuming have the throttle pegged and aren't changing anything at all. The second "pull" is the vvti kicking in. There's no gap, or loss of power during the transition.

In my instance, throttle pegged, nothing changing, the vehicle will pull, then it feels like it bogs down, or even stalls for a moment or two, then pulls much harder. There is a noticible jaunt of pull, then slowing, then pull again. Wasn't sure if that was the norm, or if I'm having fuel delivery issues/something else.

Vibes are felt in the seat/body, not so much in the steering wheel at all.

Roads are fairly clear, tho the TSS might be doing something. I'll try it with the TSS disabled, and with VSS/TSS disabled. Good idea! (Tho I didn't notice the TSS light blinking or any beeping).

Vibes kick in before the time the variable valve timing does it's thing. It will vibe all the way untill it shifts, then will kick in again around 3500 or so. Maybe it's an engine mount issue?

I'll check the driveline angles, torque on various driveline bits, and the ubolts tomorrow.

This only happens on hard accels, never other time.

And no, I'm not talking about from 0mph, more like pegging it at 15-25mph. I wouldn't abuse the truck from 0!

And no, I haven't tried this with 4wd, or should I say, I'm not brave enough to peg the motor while in 4wd on the street. I don't want to break stuff lol. I don't know if I even have a smooth enough dirt road that I could try that on, tho traction will be a new issue there haha.

 

2020 here, 3200 miles, mine also vibes in the rear on hard accels. Mine does it from a complete stop however, not from a roll.

 

Tighten the u bolts and grease the u joints if they have zerk fittings

 

Wish I could grease mine....

I enjoyed doing that kind of maintenance on my first gen 4runner...

 

Most common fuel issues with these trucks is the High Pressure fuel pump "chirping like a cricket" or the low pressure fuel pump completely failing due to the pump impeller deforming.
Either one when they fail will throw a code. The low pressure failure generally causes the engine to shut down, and sometimes not restart until it is cold (or not at all). And you will even notice a rough idle if the LP pump is getting "weak"

Sounds like what you are experiencing is the normal automatic transmission tacoma experience... Toyota has reprogrammed the shift points much better than before on the third gens but people are looking at 3rd party software (OVtune /VFtune) to make it much better.
There are a few dyno charts floating around Tacomaworld, it they show the power peaks and valleys hat you describe.
Don't look at tall the bitching about the shift points on this forum, lol you'll hate your truck for all the different issues you never noticed yet....

Since it happens only during hard acceleration...

What you MAY be experiencing is the rear springs winding up and the pinion to rear driveshaft angles getting too severe.
If the Tacoma had more torque you'd see wheel hop. But the tacoma has never been accused of having too much torque.
But it does have a very long leaf spring...

Better rear leafs, or old school slapper bar,
or increasing the angled shim under the leaf pack can fix that up.
(sometimes a carrier bearing drop will work instead of increasing the rear shim angle but not always and it can cause other issues...).

Too much angle and you'll get vibes on deceleration...

Quick and dirty test for rear pinion angle... put about 200-300lbs of stuff in the back of the bed towards the tailgate and test it again.
1 inch of drop to make it "smooth" = 1 degree added to the rear axle/leaf shim to make it smooth when unloaded.


4Hi in a straight line on a full traction road is perfectly safe for the truck.
It's when you turn you will get the difference in wheel speed that will start loading up the driveline.

4Hi acceleration test puts less "wind up" on your rear springs and less rotation of your rear axle, but keeps the same rotational speed on your drive shafts.

 

Yeah it might be the leafs binding back and causing poor angles. I'll throw a GoPro down there and see.

As far as the odd power curve, I'm not talking about it shifting and going through the powerband. It will do what I described in most gears, barring the upper ones.

I wonder if it's the torque converter not being fully locked?

Hmm... I wonder if anyone is in the sac area and can flash ovtune onto my truck with their hardware. (Do we have a thread for that btw? Flashing services or something?)

 

I think the '19's still had two zircs on the front shaft, it was 20 when they got rid of all of them....

If you live in an area where they salt the roads or you do water crossings, looks into annual oil spraying of your truck...

But don't worry, since you liked working on your 4Runner...
and have now joined Tacomaworld...
you will be working on your truck more than you planned...

I bought a brand new Tacoma so I would have a daily driver that I would not be working on all the time...
Then I joined Tacomaworld...
And for 3 years I have not stopped working on the truck...

 

Toyota tech says it’s a normal characteristic of the truck.

 

Not surprised!