I don't understand why when I'm crusing anywhere from 40-46 mph, my 5AT Type-S 08 doesn't upshift into 5th gear.

Only once you hit that magic 47 mph does it upshift into 5th gear. So I'm constantly manuall upshifting in 35-40mph speed zones (40-46 mph actual speeds)

Why does it act this way? Is it smart/stupid to manually upshift to save on gas?

Thanks IN advance

 

the older cars did that (read 01-03 maybe some 04s) until Acura did the software update. Now unless you use SS to put it into 5th, it auto shifts at 47 just like your car does. They did it to save the transmission from excessive shifting and wear.

 

If you manually upshift in 35mph zones into 5th, you can't have much power when you accelerate. I am assuming that you have to downshift immediately when you want to hit the gas? The AT most likely knows this and doesn't add that extra shift. Isn't it designed to run in a certain rpm range/throttle response?

 

Sure, acceleration is less powerful, but not to the point that I have to downshift. The only time I could see this being a problem is a long highway entrance ramp, where the speed would quickly jump from 40 to 60+

 

 

Well I just see myself in a lot of city driving situations where a upshift in the 40-46mph zone would be helpful for gas mileage!

 

Heat is the main reason. The higher the gear and the lower the road speed more heat you're going to generate. My guess is the converter is locked in 4th so you gain efficiency and seriously knock down the heat. Low speed in 5th will have the converter unlocked as well as having a large speed differential between the input shaft and output shaft which creates the heat.

 

One of the reasons I got the 6MT

 

That makes sense, but WHY do you gain efficiency? Because of less heat?

 

Ill have to give the short version since I'm typing from my phone.

Heat is the result of inefficiency. You're wasting power in the form of additional slip and it shows up as heat.

The simplest way to explain it is this. A torque converter is a fluid coupling, it performs the same job as the clutch in a manual except it will always have some slip. Slip= wasted power in the form of heat. The converter is the main source of heat in an auto. Since the 80s they have come with an actual clutch inside that engages after you're above a certain speed and in a certain gear. This gives 100% coupling like a manual and the converter is eliminated as a heat source.

Putting the transmission in 5th at a low speed is similar to starting off in second gear on a manual. The engine (input) speed will be about the same but the output (transmission input shaft) will be at a lower speed. With the bigger speed differential between the engine and transmission you have more slip and more heat. That gas you think you're saving by running it in 5th early is literally turning to heat.

The other way you're hurting efficiency is at 45mph the torque converter will apply the clutch and you have zero slip meaning less heat and more efficiency. Trying to run it in 5th at such low speeds requires running the converter unlocked to avoid bogging/lugging the engine.

 

does the type S have more "sporty" shifting points than base TLs? I know performance cars usually wait a bit longer to shift to give you more power instantly

 

My AT shifts exactly at 39mph

 

^04-06 base tl has different geared ratios than 07-08 TL, that may be the reason

 

Keeps you from lugging the engine, my Accord is the same way (pretty much the same transmission, I believe). Honda engines aren't really known for low end torque and lugging the engine in a big gear is tough on it.

 

My 05TL shifts to 5th at 48-50mph but when i am on SS mode- i make it go to 5th at 42mph- higher gear less gas lol

 

cruising at 40-45 mph in 4th you should still be below 2k rpm. not a considerable amount of fuel saved, but idk if its worth it putting the strain on the tranny. because as soon as u touch the brake or go up a hill your gonna down shift.

 

You can't actually lug the engine because the torque converter has a stall speed of at least 2,000rpm. In theory you could be in 5th at 20mph and if you're accelerating rpms will be well above the lugging threshold. What you will have is a boatload of slip in the torque converter and a lot of heat. This will overheat the transmission quicker than just about anything else you can do.

Not with an auto. RPMs will not drop because the torque converter unlocks. You lose the mechanical leverage advantage of 4th gear so it requires more throttle and you lost the efficiency of the locked converter. There's also decel fuel cutoff to consider. Once you're off the throttle and coasting and as long as the rpms are above around 1,200rpm the injectors are shut off completely. That's not going to happen in 5th gear.

The other thing to think about is wear occurs on shifts. Each time you shift you put some wear on the clutch packs. If I'm in ~45mph traffic I'll lock it out into 4th to make sure it doesn't hit 5th gear, especially in the heat we've been having lately.

 

IHC

 

/thread

 

True

When coasting on 4th gear- 40mph and less, i am off the throttle and the rpm is at 1700-1800 and thats why i go to 42+mph if possible so i can shift to 5th gear and the rpm drops to 1200 like you said.

I agree with you- i thought about wearing the clutch packs faster that way and now i am more hesitant to shift to 5th gear because sooner or later i have to brake and it drops to 4th gear again

 

I just leave it in D mode, if I do SS then 5th gear wont be shift until 55 mph is reached.

 

Good info in this thread. I was a little hesitant to use the semi auto shifter as i was not sure what kind of additional wear it would be putting on the transmission, now i know. I guess I'll just be using it to drop a gear when on the high way to leave those Civics and Accords in the dust. I love how the TL is such a sleeper... those who dont know, never see it coming lmfao

 

Also i've noticed a few things. When using SS... from a dead stop it shift from 1st to 2nd AUTOMATICALLY.

another thing to note is that per the manual, the system will not let you down shift to a lower gear that will max out the RPM's... great feature.

lastly, it seems to auto downshift when the current gear and engine RPM's are too high for your current speed.

This car is SMART. I'd make love to it, if i was into that kind of stuff lol

 

this thread is done. IHC has chimed in and gave the word of god

 

not sure about the 04-06 model but all the 07-08 model does not shift 1st to 2nd Automatically in SS mode.

 

The older ones did, my 01 CL-S used to upshift to 2nd in sport shift, was quite annoying. Also, i don't think you could start off in 2nd with the older models like you can with the later models. That was a long time ago.

 

I can confirm that my 08 will not automatically shift to second. Hate when I forget I'm in SS after a stop