Annoying vibration below 1500 RPM while moving.

I have a 4-cyl with auto trans., access cab.

I have started to accelerate without going over 2000 RPM to save gas. Basically, driving like a senior citizen would, perhaps.

I am hearing and feeling an annoying vibration, when the tachometer falls below 1500 RPM, after the transmission shifts into 2, 3, or 4th gear.

I can feel it with my feet. It only lasts a half second and goes away....even if it stays at that RPM for a while longer.

I am not running over rough pavement. I cannot find anything that needs tightening underneath.

I am thinking I might be lugging the engine, but is it possible to lug an engine with an auto trans?

Everyone...go try this and see what you get. Really.

Kevin

 

Hey Kevin,

Are you manually shifting the auto trans?
Are you trying to keep it below 2000 rpm's?

Just wondering - as the auto tranny would be hard to keep it at any rpm range unless you were shifting it manually.

Are you driving when you're doing this?

Have you tried doing it while you're sitting still?

Lugging with the engine in an auto would certainly depend on the terrain and how much gas you're applying. If you'r not applying a lot of gas and going up a hill - perhaps the engine could lug along.

I've realized with my 4.0L that it doesn't always downshift when you think it should for optimum power band. It's almost like you gotta step on the gas a bit harder to get it to downshift. But...that's my paticular 4.0L. I don't know how the 4cylinders work.

 

I have a 4.0 and have experienced what you are talking about but have never found a solution. Mine does it only when driving not when in park or neutral. I am not shifting it, however I have not tried to recreate it while I was shifting. I was on a paved driveway. It is when accelerating slowly usually pulling away from a stop sign rather than a red light, I believe because at the light I am usually pacing with traffic not to hold anyone up, their in such a rush.

 

I am driving. The transmission is doing its thing.....I am not manually shifting.
I am trying to accelerate and keep the RPM 2000 and nothing more. So far, I have gotten 160 miles at the 3/4 tank mark. Before, I got 125 miles.
Idling the engine up to 1200/1500 does not give me any vibration.

Thank you. I am not crazy. I may be lugging the engine then.

 

Yes mine does that as well. Seems fine when on a flat road but if you start going up a slight incline it does seem to bog. I don't think its any issue that is going to cause a problem. Sometimes I just slap the stick to the left or 3rd gear and then when i get back to flatter grounds slap it back to drive.

I also find it interesting that 4th gear almost feels like a CVT tranny. it shift into 4th at lets say 2200 rpms and then it drops even more to like 1500/1600 rpms. I averaged 24.6 mpg last tank. On highways I go about 80 to 85 mph. Hope that helps. Anybody else care to add?

 

I'd say it probably normal considering you're forcing the truck to stay below 2000 rpm's regardless of what gear the tranny is in or the terrain.

How exactly are you keeping the rpm's below 2000? Are you watching the tach constantly and letting your foot off the gas everytime it upshifts?

What kind of speeds are you getting while doing this?

I can't imagine how much time you've gotta spend watching the tach.

 

LOL. At least I am not on the phone doing this.

With practice, I can accelerate and keep the RPM at 2000 in 1st & 2nd gear, by listening to the engine. I am keeping the same pressure on the pedal, letting the transmission do its thing, not increasing the pressure on the pedal.

The engine will shift at 2000~2200 into all the gears.

It shifts at 15, 25, & 40 MPH approximately.

At 4th gear, it shifts at about 40 MPH and the RPM will fall below 1500.

Kevin

 

I have gotten used to the sound of the engine and just baby the pedal to keep it below 2000 rpm. My girlfriend thinks I'm crazy for doing this, I'll use you as an example to show her I'm not the only one.

 

The shift from 3rd to 4th is a big jump, and seconds later the TQ locks up, and at that point the engine will be lugging a little, and I think the lugging is the noise/resonance/vibration you are getting. People have always complained about constant upshifting and downshifting due to tall final drive ratios coupled with even taller overdrive ratios; Toyota has evidently set the transmission to require more pedal input before downshifting back down to 3rd once it has hit 4th(od). I would try letting the 3rd to 4th shift occur at a higher speed; say 2250-2300 and see if that raises the RPM's enough to make things smoother. The 2.7 has good torque, but by the time you are shifting into 4th, the wind resistance is up, also remember the Tacoma's are a little heavy, and if you shift into 4th @ 40 MPH and continue acceleration to 55-60; you are probably having to very gently apply more and more throttle to get from 40 to 60 and don't realize that a downshift for 1 second would probably be more helpful getting there than just keeping the trans in 4th. Try it this way also; when on highway make the 3rd to 4th shift occur @ 75-80% (45-48MPH)of your desired cruise speed of ~60 lower on level/downhill, and at the higher end on slight uphill grades or into headwinds. Remember; when the auto od trans is in 4th with the TQ locked, and @ 1500 RPM, it is just like a manual 5 or 6 speed in the highest gear, but with the automatic just a little more accelerator pressure will let the TQ unlock and/or downshift to 3rd to prevent lugging. Toyota could have calibrated the trans where it up and downshifts constantly like some GM's and Fords do when the load changes 1/2%, but they chose not to, but one should not go out of the way to hold a gear till it lugs, let it downshift if it lugs. if you had a Scan Guage, you can see that higher throttle inputs at very low speed actually yields worse instant MPG figures. If that don't work, just disregard everything I stated.......

 

That makes sense. Seems that a few of us are trying to drive in a way to be saving fuel....and making people behind us blow their horns at the same time.

Thanks. I really appreciate your thoughtfulllness....and all who have answered.

Kevin

 

What's the difference in working the tach (the method you mention) versus just slowing down 10mph and driving normally (not worrying about rpms)?

That just sounds like too much work & effort. I'm busy enough keeping my eyes on the road and watching for dumbfarts plus my hearing ain't that great to listen to the RPM's while my tunes are playing (somewhat loudly).

 

I drove ~100mi round trip today to go to a VW show to look and to pick up a few odd parts for my recently purchased VW type 181 (aka Thing) and at times tried to do the shift at 2K RPM. It only bogged a little at times, and other than traffic backing up into neighboring states, everything was OK. Throttle response is nil at this point, and I was giving just enough throttle to what I thought would prevent a downshift were I driving an automatic, but even flooring the accelerator would only give a barley noticeable increase in performance. In my case the 4th to 5th shift was the most likely to bog and cause slight bucking, and the automatic has an even larger jump from direct to overdrive. So my hypothesis was correct, dropping to 14-15K @ upshift will cause some bucking and shaking, more so just the driveline flexing on the engine/trans rubber mounts until the RPM's rise just a little. I will try more later when less traffic is present. If just delaying the 3rd to 4th shift only will stop the problem, continue 1st-2nd and 2nd-3rd at the lower RPM and delay the 3rd-4th

EDIT: Everything Janster stated was basically the same conclusion I reached, you have gotten to the point of lugging the engine.

 

I had same problem with 2007 Tacoma after 24,000 miles,
Shift into third gear @ low rpm created vibration.
Dealer corrected the problem 8/20/2010 with a chip upgrade from Toyota
Toyota knew apparently knew about this problem although the dealer did
not until I brought it to their attention.

 

I have a 2019 Tacoma first one and I love it but I also have some issue while driving at slow speed I try to keep rpms at around 15 it feels like it is puttering I feel it like I need to downshift but it is automatic I try to baby this truck I want to have it a long time but I don’t know how to fix the problem