using 4 or D? (transmission)

jimmy2020 · 03-27-2006, 07:25 PM

I'm used to driving a 6 cyl Tacoma and I recently purchased the Titan (love the V8). It seems like the truck shifts and runs at very low rpm's. When not on the highway, does anyone keep the tranny in 4 and not D. If so, can u see much of a difference in fuel economy.
I must say I do like to play with the shifter as if is more of an auto stick.

I like hearing the V8 revup.
Jim

CHEIF · 03-27-2006, 08:07 PM

I've found that in the city, 4 comes in handy. I usually don't hit '5th' anyway.

You'll also notice that the tranny downshifts more in 'D' when braking down a hill. It helps keep your foot off the brake, but you are also running at higher RPM's and using more fuel. That's what I noticed.

Sometimes when it downshifts in 'D' when coasting, I put it in '4' and the revs drop. Usually I just leave it alone though.

Cheif

sudden urge · 03-27-2006, 08:16 PM

Under 50 mph, I'm using it more and more in 4 than drive because I noticed if you're driving at a steady 40 ish, it will shift into overdrive and the rpm's are so low it wants to buck a litttle. That i don't like, so I only use drive when running over 50 mph.

SUBTITAN · 03-27-2006, 08:38 PM

I stay in D unless towing a heavy load then I will drop into fourth. That is to save the tranny from overworking.

Smoke05 · 03-29-2006, 08:57 PM

Quote:

You'll also notice that the tranny downshifts more in 'D' when braking down a hill. It helps keep your foot off the brake, but you are also running at higher RPM's and using more fuel. That's what I noticed.

The engine isn't using gas to slow you down, it just down shifts a gear. You only use more gas if you step on the gas pedal. It is also called engine braking. People with standard transmissions do this all the time.

**helomech** · 03-29-2006, 09:04 PM

Like smoke said not using more fuel, just because the rpm went up.

CHEIF · 03-29-2006, 10:01 PM

Quote:

Originally Posted by Smoke05

The engine isn't using gas to slow you down, it just down shifts a gear. You only use more gas if you step on the gas pedal. It is also called engine braking. People with standard transmissions do this all the time.

That is incorrect. Fuel is fed to keep the engine firing at all times. More RPM's = more firing = more fuel. You aren't stepping on the accellerator, but every cylinder is still firing. There is also a control to feed some fuel as the engine rapidly decelerates, like when you gun it in neutral.

Not the same as stomping the pedal but it still uses more fuel.

The only situation I can think of where it's not true is on a properly set-up 2 stroke MX bike. It should only idle for a few seconds then die with no throttle for engine braking.

Mileage also takes a sharp drop because of RPM's on the highway, I can do 75by using hardly any pedal, but I'd get much better mileage at 1500 RPM's and 55 MPH.

**helomech** · 03-29-2006, 10:07 PM

Not necessarily cheif, just because rpm increases with gearing doesn't mean the fuel injection is feeding anymore fuel than when idling. I some carbs that use airflow to control fuel flow that would be true, but not with fuel injection. RPM doesn't control fuel flow.

CHEIF · 03-29-2006, 10:20 PM

**loufish** · 03-29-2006, 11:11 PM

I keep it in 4th below about 50 mph...my issue is with the converter slippage. The converter doesn't want to lock up till at least 60 mph, and it doesn't take much to get it to unlock.
I believe this got worse when I went to 35" tires...

**Helinut1970** · 03-30-2006, 05:51 AM

Quote:

Originally Posted by SUBTITAN

I stay in D unless towing a heavy load then I will drop into fourth. That is to save the tranny from overworking.

Ditto...... Couldnt have said it better myself.

**goathead** · 03-30-2006, 07:57 AM

i keep it in D pretty much all the time....sometimes though, i will drive in 3rd when running errands on the local strip just to be "ready"....

SUBTITAN · 03-30-2006, 08:36 PM

Quote:

Originally Posted by goathead

i keep it in D pretty much all the time....sometimes though, i will drive in 3rd when running errands on the local strip just to be "ready"....

Too funny.

CHEIF · 03-30-2006, 09:22 PM

That is pretty funny. Musta read it too fast the first time, I thought he said "Just to keep it steady"

miketan · 04-02-2006, 04:53 AM

I used to drive around with the tranny in (D), but I've found using (4) is much better in the city. In (D), the tranny seems to shift in and out of overdrive too much and the automatic downshift feature when braking down hills is a little distracting.

In (D), the tranny likes to short shift into the next gear which lugs the rpms down. If you need to accelerate quickly for some reason, you practically have floor the pedal to get it to downshift and then upshift into the proper gear for maximum acceleration.

With the tranny in (4) in tow-mode, the upshift into overdrive is eliminated and each gear holds longer under load. This makes the truck feel less sluggish around town.