High idle momentarily while shifting gears

[willtill]

Greetings,

I picked up a new 07 4x4 TRD Tacoma V6 a couple of months ago. Have downsized from an 02 F350 diesel (what a difference!) Anyway I have a question regarding high idle and shifting the manual transmission.

When I am shifting up in the gears, the motor will continue to maintain it's rpm's for about a second or two, after I have depressed the clutch and let off of the accelerator pedal. It will do this as well when I come to a complete stop. It will idle high for a couple of seconds and then drop.

Doesn't matter if the engine is cold or warm.

Is this typical behaviour for this type of truck?

Kindest Regards,

-Will in Maryland

[Viper-2]

Originally Posted by willtill

Greetings,

I picked up a new 07 4x4 TRD Tacoma V6 a couple of months ago. Have downsized from an 02 F350 diesel (what a difference!) Anyway I have a question regarding high idle and shifting the manual transmission.

When I am shifting up in the gears, the motor will continue to maintain it's rpm's for about a second or two, after I have depressed the clutch and let off of the accelerator pedal. It will do this as well when I come to a complete stop. It will idle high for a couple of seconds and then drop.

Doesn't matter if the engine is cold or warm.

Is this typical behaviour for this type of truck?

Kindest Regards,

-Will in Maryland

Yes it is, the 6 speed manual does this but not the 5 speed. If you do a search here or Toyota Nation you will see a lot of discussion about it.

I believe the general consensus is that Toyota does this as an efficiency emission thing.

I personally could not get used to it on the test drive so I opted for the 5 speed manual.

[concrete jedi]

Yeah it's a pain to get used to, but it actually made me a better driver, more concerned with my revs, I find it best around 2000 rpm, and quick shifts.

[jtsimaras]

It does do it with the 4 Cylinder as well.

[jtsimaras]

Drove my WRX again for the first time since I bought the Taco---10 days ago. WoW--Freaking FAST. The Taco has forced me to drive different as a result my shifting style has changed in the WRX as well --- for the better.

[TSUNAMI*22]

One day I was about to coast a large (5 minute or so) downhill in my 2.7 manual 5-speed and just to see what mileage numbers I could get (i have scangauge), I depressed the clutch with the shifter engaged in 5th gear. The RPM's stayed at 2,100 (where I was cruising at) for approx 30 seconds before dropping to idle.

Now, with that being said, when I decelerate first before depressing the clutch (engine engaged braking) the RPM's immediately decrease to idle.

By the way, I accidentally found that coasting downhill with the tranny engaged for more than a few seconds actually shuts the fuel off to the engine (as opposed to coasting by depressing the clutch and idling).

How do I know that the fuel shut off? The scangauge II shows real-time temperature (water) and it decreased from 195 to about 168 during the 5 minute coast downhill. It can only decrease like that because there isn't any fuel burn to create heat. In that 5 minute coast I managed to go from a trip mileage of 28.6 mpg to 33 mpg. After I resumed normal driving for approx 1 hour I eventually netted 29.8 mpg for the trip. This was obtained at 70 mph average. At the same time I began the descent I noted the (trip), (current), and (tank) mileage increasing dramatically.

The large downhill that I speak of is in the southbound lanes from the top of the Grapevine down into Castaic, CA. Anybody who lives there should know where I'm talking about.

Also, the water temp needle never moved from it's original position.

Bottom line: decelerating with engine engaged to tranny gets better mileage than just coasting with the clutch depressed at low rpm idle.

[MotoXFreeStyle61]

Originally Posted by TSUNAMI*22

One day I was about to coast a large (5 minute or so) downhill in my 2.7 manual 5-speed and just to see what mileage numbers I could get (i have scangauge), I depressed the clutch with the shifter engaged in 5th gear. The RPM's stayed at 2,100 (where I was cruising at) for approx 30 seconds before dropping to idle.

Now, with that being said, when I decelerate first before depressing the clutch (engine engaged braking) the RPM's immediately decrease to idle.

By the way, I accidentally found that coasting downhill with the tranny engaged for more than a few seconds actually shuts the fuel off to the engine (as opposed to coasting by depressing the clutch and idling).

How do I know that the fuel shut off? The scangauge II shows real-time temperature (water) and it decreased from 195 to about 168 during the 5 minute coast downhill. It can only decrease like that because there isn't any fuel burn to create heat. In that 5 minute coast I managed to go from a trip mileage of 28.6 mpg to 33 mpg. After I resumed normal driving for approx 1 hour I eventually netted 29.8 mpg for the trip. This was obtained at 70 mph average. At the same time I began the descent I noted the (trip), (current), and (tank) mileage increasing dramatically.

The large downhill that I speak of is in the southbound lanes from the top of the Grapevine down into Castaic, CA. Anybody who lives there should know where I'm talking about.

Also, the water temp needle never moved from it's original position.

Bottom line: decelerating with engine engaged to tranny gets better mileage than just coasting with the clutch depressed at low rpm idle.

I too have noticed the same thing with the high idle and the better mileage with the tranny engaged. By the way, where the heck do you find 5min downhills? I live out in the saltflats of Lubbock TX, and the longest downhill ride is usually measured in milliseconds.

[TSUNAMI*22]

There's a mountain range that separates Los Angeles from the central San Joaquin valley in CA. The grades lay within it.

[Viper-2]

Originally Posted by jtsimaras

It does do it with the 4 Cylinder as well.

It does? This is the first I've heard of this on any forum. Mine is a 5 sp manual and has never done it.

Can you let me know where you heard this so I can check it out?

[jtsimaras]

Originally Posted by Viper-2

It does? This is the first I've heard of this on any forum. Mine is a 5 sp manual and has never done it.

Can you let me know where you heard this so I can check it out?

Oh ya It is actually mentioned in this thread. You would never really experience it unless you do highway driving alot. If yours doesn't do it your lucky or something like that.

[jtsimaras]

Originally Posted by TSUNAMI*22

One day I was about to coast a large (5 minute or so) downhill in my 2.7 manual 5-speed and just to see what mileage numbers I could get (i have scangauge), I depressed the clutch with the shifter engaged in 5th gear. The RPM's stayed at 2,100 (where I was cruising at) for approx 30 seconds before dropping to idle.

Now, with that being said, when I decelerate first before depressing the clutch (engine engaged braking) the RPM's immediately decrease to idle.

By the way, I accidentally found that coasting downhill with the tranny engaged for more than a few seconds actually shuts the fuel off to the engine (as opposed to coasting by depressing the clutch and idling).

How do I know that the fuel shut off? The scangauge II shows real-time temperature (water) and it decreased from 195 to about 168 during the 5 minute coast downhill. It can only decrease like that because there isn't any fuel burn to create heat. In that 5 minute coast I managed to go from a trip mileage of 28.6 mpg to 33 mpg. After I resumed normal driving for approx 1 hour I eventually netted 29.8 mpg for the trip. This was obtained at 70 mph average. At the same time I began the descent I noted the (trip), (current), and (tank) mileage increasing dramatically.

The large downhill that I speak of is in the southbound lanes from the top of the Grapevine down into Castaic, CA. Anybody who lives there should know where I'm talking about.

Also, the water temp needle never moved from it's original position.

Bottom line: decelerating with engine engaged to tranny gets better mileage than just coasting with the clutch depressed at low rpm idle.

Pretty cool investigation!