The truth about rev hang in the Manual Transmission.

It's just needs to be broken in.

Before I bought my truck, I test drove a used 2016 and new 2017 (both manual), and I noticed a big difference in the transmission feel. The used 2016 felt significantly better.

I definitely remember having rev hang when I bought my 2017, and I really delayed my shift from 1st to 2nd. My muscles already got used to the delay. Today, I decided not to delay my shift just to see what would happen. To my surprise the rev hang was completely gone.

Here is graph of one of my most recent trips (recorded with the Torque app). The X-axis represents each second of my trip. The Y-Axis represents both the RPM(/10) and my Speed. I divided the RPM by 10 for presentation purposes. I wanted show my speed and RPM in a concise way without messing around with so many graph settings in Excel.

The RPM record clearly shows that there is no rev hang. For example, after the second stop light (see below), I shifted quickly, with the same speed from 1st to 4th, and there was no hang at all.



Please pardon the misspelled "3nd" labels...

 

my trick has 15k miles and still hangs

 

Can you please change your graph to a much larger scale to show on the horizontal axis just the short duration between top revs 1-2, around 120-125 second mark. Thanks

 

I have 25k and the rev hang is the same as new

 

It's an emission thing. Sucks but it is what it is.

 

Why is this good for emissions?

 

You may want to read this.

 

When the throttle is closed between shifts the ECU would normally reduce the amount of fuel being injected to, or near to, idle levels--but with the engine still spinning faster than idle this would create a lean mix, pushing up oxides of nitrogen (NOx) emissions. By keeping the throttle open a bit, for a bit, the NOx. emissions are reduced.

As emission requirements have become more stringent the "hang" has been made more annoying...

 

8k miles in and mine still hangs. The quicker I am on the shift the less I notice it. If I take my foot off the gas a second or two before shifting,trying to anticipate the hang, it actually hangs longer than doing a split second transition between gas, clutch, gas.

 

Awesome. I love learning new shit. Thanks guys.

 

Here you go! Doesn't appear to be any rev hang at all. There is a bit more than 1 second in between my shift from 1st to 2nd. It's not a super fast shift, but it's not a relaxed shifting speed either.

 

What is the mileage on your truck currently? Or when did you notice that the rev hang disappeared?

Did you ever run the torque app when you had rev hang to see if it captured it on the graph?

 

I have had the torque app for one week. I bought the 2017 Tacoma in the beginning of May. It had 150 miles at that point. It currently has 2900 miles.

 

6300 miles, still getting rev hangs..

 

All vehicles have rev hang over the last bunch of years, including yours. It's an emissions thing

 

Keeping the throttle open means injecting fuel to make it richer.
So, extra fuel is injected in order to reduce the emission?!

 

Take it out and run it to the redline between each of the first 4 gears and you will see the rev hang. It is way worse at higher rpm's. Gets a 2nd gear scratch without my foot on the gas! Never had a manual do that and I have owned a bunch.

That said I don't notice it as bad under 3000 rpm.

 

Exactly right, slightly longer duration of injection does the trick but gives you rev hang.

Thanks, is it possible to stretch the graph even more, just over 5 seconds on X -axis to show the detail between 17 and 24 second? I would like to compare it with this my graph.

I agree that rev hang gets worse at higher revs. The above referenced graph shows extreme situation (8K - K20 engine in Civic Si, admittedly a very different beast from Tacoma). Still, it illustrates the rev hang well when trying to shift gears quickly.

 

Your graph shows it takes 3 seconds to drop 1000 rpm (3500-2500). Seems like that's too much

 

No it doesn't, it does not make it rich. With "fly-by-wire" throttle control the ECU can do whatever it likes. What it does during the "hang" is keep the throttle open a bit and inject sufficient fuel to keep the mix stoichiometric--thus making the Feds and the "tree-huggers" happy.

It's a new paradigm, the old way where directly controlled (i.e. cable controlled) throttle position ruled, is all over and done with...