nycACURA

Just wanted to ask you guys if you experienced your car slowing down by itself when you take you take your foot of the gas. I feel the car slowing itself down. It feels as if the brakes are being applied. Just want to know if this is normal. i have 5at.
-vee

6mtV6

When I had my 5at I felt the same thing. I think it's normal.

the4chews

Is this happening when going down hill by chance? I have been told it is normal and is the way the trans is programmed, especially when going down hill.

crazymjb

Makes sense. Not sure on the specifics of this tranny though. To test it for breaking put it up on a lift and see if the wheels spin freely. What RPM are you at when this occurs?

6mtV6

It happens to me when i'm driving at a constant speed and let go of the accelerator to slow down. I guess it's a characteristic of the 5at.

bluenoise

Yeah, I was just going to post a similar thing this morning. It bugs me. When I'm slowing down, whether on a downhill slope or gently approaching a stop, the downshift around 40 MPH feels like I suddenly applied too much brake. I've had to apologize to passengers and explain I wasn't trying to make them kiss dash. Sometimes, I anticipate it and switch to manual mode while slowing and then popping back to auto once stopped.

nycACURA

It usually happens at low speeds(2500-4000 rpms). But sometimes it happens at high speeds

dsc888

It't totally normal. It's part of Grade Logic that Honda programs into the auto tranny to help with braking. It downshifts rather quickly into a low gear so that you won't over heat your brakes. It's esp. noticiable when going downhill. I like it personally as I don't have to ride the brakes much while going down hill.

dsc888

bluenoise

I find I still need to ride the brakes on most hills in my area. In that case, I switch to manual and lock into third or second, depending on the desired speed. I wish it could either be disabled or smoother in its engaging. When it happens, it's rather startling.

nycACURA

thanks dsc888... i was worried all day today

crazymjb

Another thing to add to the safety features section of my paper, thanks guys.

dsc888

No problem, man. The Grade Logic is a bit abrupt compared to my 97 Camry V6. I still need to hold the brakes on hills that are not so steep as it barely kicks in enough. It take advantage of a phenomenon known as "Engine Braking" where it uses engine compression to slow the car down. Tractor trailors and buses do it all the time as they slow down. That's the "farting" noise you hear as the driver slows for the red light.

dsc888

madehtsobi

yeh i feel it in my auto...espescially when i come off the freeway and goto about 40mph and i feel it kinda kick back......kinda cool....saves my brakes!

Hou-RL

dsc888,


I totally about the grade logic but it is also a function of the drive-by-wire feature of the car also. The drive by wire also adjust the accelaration and deceleration of the vehicle when you depress te pedal.

KJSmitty

Then again it could be me if I'm parked next to ya....

--I think it helps the "butt prints", but I digress......

sebounet2005

I noticed in low position that the change is very hard. It could be surprising when you take a turn an d the AT decides it,s time to go to the lower gear.

ONAGER

dont forget that slowing effect is also related to engine or compression braking.... the higher the compression the more the effect. to which the tl has a lot of compression....

dsc888

HAHAHAHAHHAHAH! Thanks for the laugh.


dsc888

dsc888

As always, you make an excellent point. I feel like it drops to 1st gear each time I slow and torn down a hill near where I live. It's like a 28% grade (read steep) and it causes the car to shudder for a moment as it goes from 3rd or 2nd into 1st.

dsc888

ONAGER

i really do try

Repecat

It is my understanding that "compression braking" is a misnomer. The braking effect has nothing to do with compression; it is internal engine FRICTION that causes the vehicle to decellerate. The point is that Honda's "grade logic" system really works (maybe sometimes too well) and I like it. Kudos to Honda.

rgorsk

I actually like this feature too. When I used to drive a stick I always downshifted to slow down. I have the 5AT now and I usually use the SS and to downshift myself, but when I'm in auto mode I like that it downshifts to slow down on its own.

Brewmaster

When I first got the vehicle this would sometimes catch me by surprise .. between my braking and the car braking it could get a bit harsh at times .. over time I've learned to anticipate it and it's smoothed out quite a bit ...

(actually I think I've smoothed out, the TL never had the problem I did ... hmmmm just like being married )

golferboy1862

I don't mind Acura's "grade logic" system but prefer to use my brakes rather than the engine to brake. I don't want the additional wear on my engine and replacing the brakes is much cheaper than rebuilding or replacing the engine in the future.

dsc888

I understand your reasoning but there is virtually no damage to the drivetrain. If I remember correctly, the 5AT's torque converter can lockup in 2nd, 3rd, 4th, and 5th to help with fuel ecomomy. Someone correct me if I am wrong. But that would mean no slipping of the tranny and practically no wear. Plus you won't overheat your brakes which can occur if you are going down a very, long hill.

dsc888

EnJ

Damn, a lot of people replied to this which makes me hesitant to post but I'm gonna do it anyway. That was one of the first things I noticed when I first drove the car; it doesn't coast at all. Seems like you constantly have to apply the gas to keep moving otherwise you'll come to a complete stop relatively quick.

golferboy1862

I don't imagine the drivetrain would have much, if any, additional wear but your engine would. Over time you'll lose compression and as compression goes so does performance.

GUMP

It's Definitely "engine Braking".. All Hondas Use It. Nothing To Worry About. A Little Annoying, But Useful.

Rick F.

Actually, compression is probably the biggest part of the braking effect that you feel. If you turn an engine over by hand or with the starter with the spark plugs removed (no compression, but same level of friction), you'll feel surprisingly little resistance. Try the same thing with the plugs back in, and the difference due to compression is substantial (even at the approximately 6 rpm that you can manage by hand!)

At relatively high speeds, incidentally, wind resistance also contributes to the braking effect. If I remember correctly from my SCCA racing days, the combined effect of compression, engine and chassis friction, and wind resistance--but no brakes--would produce upwards of 0.4 g deceleration at around 100 mph (and that's in a low, slippery sports-racing car).

Rick

KJSmitty

Think about what is actually taking place in the engine and what you are saying....

If engine wear was even a factor with the TL's "engine braking" (and it's not), you would have less wear during this braking effect than you would during normal cruse or acceleration.... With your foot off the gas you have significantly reduced the “combustion” within the cylinder thus have reduced “internal forces” on the engine…..

The only difference with the TL from other vehicles is at lower speeds the computer allows the throttle body to close to idle and the tranny to downshift to lower gears etc. to facilitate braking…. It’s an energy saving benefit.

If your that concerned with having reduced compression i.e. rings and valve wear, you best not start the car.

It's a good thing that yes, may take some getting use to, but has absolutely no ill effects on the engine or trans.....

golferboy1862

Of course there is less wear then when you're accelerating but that's not my point. Everytime the motor is used to brake there is more wear on it that's just simple physics. You don't have to be a dickhead!

AnthraciteTL

That's normal for the car to slow down. However, it should not be that noticeable. When in doubt, just call the dealership and ask.

KJSmitty

Sorry you took my response that way,,, but your actually wrong on both accounts.
--Engine braking in regards to the TL causes no "additional" wear on the engine.
--I am not a dickhead.

I just don't think a bunch of TL owners need to be thinking they are inflicting "additional" engine wear while they are benefiting from Acura's "grade logic" feature.

That is all.

Have a good weekend

alextclam

we also have a brake assist feature. it senses when you let go of the gas pedal abrubtly and starts braking before you step on the brakes.

zoeyridley

Wow, great info guys. I just got my car back from the dealer because I was discribing the same problem. At first I thought it was my brakes sticking but then realized that it had to be the downshift. The dealer of course could not duplicate the conern so to them the problem did'nt exist. I guess I'll have to learn how to brake TL STYLE!!

bluenoise

Well, there is a difference between compression braking in our car versus what's happening with big-rig trucks. It's not so much the compression that's slowing down a gasoline engine. It is a combination of friction and suction. When the throttle body is closed, it starves the engine of air. When a piston is on its intake stroke and the throttle is closed, there is quite a bit of resistance and this slows the engine down. The compression is actually more than negated by the ignition stroke that follows, so calling it "compression braking" is a bit misleading. On a big-rig, they use what's called a "jake brake," which closes off the exhaust system to create backpressure to slow the engine. Its generic term is "exhaust retarder" or "engine retarder." This is the loud augh! sound they make when slowing.

golferboy1862

I totally agree bluenoise. To call it compression is really not correct but more friction. The auto TL does this so slightly using the "grade logic" system that you can feel it but the engine rpms climp very slightly. In a manual ( 6 spd) you'll see, hear and feel it much more because the driver will generally gear down sooner than the "grade logic" system.

Repecat

Absolutely...Thats what I said back in Post #21. It's amazing how urban legends get carried through. I had kinda forgotten about "Jake Brakes" until Bluenoise mentioned it.

SnappyPappy

Yes, if the car detects an incline it down shifts to use engine backpressure as a braking force. It's called "Hill Logic" and works in conjunction with your 'drive by wire' throttle and tranny controls. But normally the car WILL slow down to some degree with not throttle because of drag forces.

SnappyPappy

I do not think that is the correct interrpretation of 'brake assist'. I believe it is applied when the brakes are activated giving an incremental boost to the drivers braking efforts. IMHO . . .