EmersonHart13

iTrader: (3)

Why doesn't my car go into 4th gear until 49 mph? Around 2K rpms?

I did a semi-scientific method of setting the cruise and switching into manumatic mode to see and 49ish is when it went to 4th....

That seems late?

Enlighten me,

John

deft

iTrader: (7)

what about in manual mode? i can manually shift into 4th at 25+

i have had a problem where my car would limit the shifts a bit higher. i never got any advice on it other than: restart the car.....disconnect the battery. this doesnt occur very often, probably 3 times since ive owned the car. the transmission is running around 200 degrees when it acts up....i cant use 4th gear until 55 at this point.

EmersonHart13

iTrader: (3)

Yeah Manual mode is fine, I just don't get why the car would not automatically shift into 4th sooner?

And that doesn't sound good at all!

Nacho SS

iTrader: (4)

I think the problem lies in setting cruise control.....the car almost goes to sleep on me!

TiredGXP

iTrader: (2)

Yeah, but check out your RPM when manually shifting into 4th below 80 kph. The engine is really lugging. Trust me, the knock sensors are working overtime with any throttle at all, and you will have to lean on the gas to get any acceleration. I'm sure I saved a log from last summer that shows 12 degrees of knock retard when lugging the engine in 4th.

I played around with manually shifting early, the DIC shows that the instantaneous fuel economy is the same, or better, in third gear at lower speeds, probably because the engine is in an area of the power band where there is better volumetric efficiency.

If you are really bent out of shape over the speed it shifts into 4th, you can always tune for earlier shifts, just don't expect better mileage or drive-ability.

Edit to add image of stock shift table (in mph)

EmersonHart13

iTrader: (3)

Excellent info, I understand what you are saying and that really makes sense. I figured it was probably something to do with efficiency but I could not figure it out, and your attachment is a great piece, thanks!

ChipC

That is to protect the tranny from overheating. While it hasn't overheated at that point, it is moving to a lower gear to prevent introducing more heat into the tranny.

Chip

TiredGXP

iTrader: (2)

Yep.

There are separate shift speed tables in the TCM for when the transmission is running hot. My experience is that the trans fluid has to be just over 101*C (214*F) for the hot table to become active.

Here's a shot of the shift speeds in the "Hot" table (km/h)

Nacho SS

iTrader: (4)

Our trannies sure do get hot quick!

deft

iTrader: (7)

you nerds with your km/h i dont know if im actually getting the same thing....

i attached the american version of what you showed and im definitely not needing to hit 70 mph to shift to 4th----that and im pretty sure im not getting up to 214 but its at least close--so i could be wrong about the temp portion. im not sure hp tuners takes into account the tapshift settings fully.....i know its a combination of rpm and speed, but there are certain unchangeable speeds that you must hit to allow you to manually shift--and i havent found these in hp tuners yet.

TiredGXP

iTrader: (2)

Well, this table is only in effect with the gear shifter in "D". As you noted, you can shift into 4th using tapshift at lower speeds. This table did come into effect for me last summer after several minutes of first gear, high rpm running while logging data to fill out the VE table. If I recall correctly, it wouldn't shift into 4th automatically until the tranny temperature dropped below 101 to 102*C

Our tables are the same, your's shows 75 mph, which is essentally the same as the 120 km/h in my table.

Eventually the US will crawl out of the stone age and start to use a sane system of measurements

deft

iTrader: (7)

at least if we switch to km/h our cars will be ready sometimes i like to switch it into that mode so my hud says im going super fast!

so my problem is still a mystery? it sounds as if you got it with high tranny temp, but what table controls the manual shift points?

TiredGXP

iTrader: (2)

I'm also a member over on the HPT forum. Chris@HPT has indicated in numerous threads over there that there are always tables in the tune that HPT has not made available for us to tune (sometimes for liability issues, sometimes because they don't think that the table does anything useful...).

I suspect that the manual shift table is one of those. I don't usually bother with tapshift, so I've never been worried about that too much, and haven't had much in the way of problems in selecting the gear I want when I do use it.

From what I remember, the limitation most often encountered seems to be in downshifting to first gear at speed - probably to prevent shocking the transmission internals with high rpm downshifts. I can live with that if it lets the tranny live longer.

Compg

You can tune this table. I've done it on my 04 GTP Comp G using a DHP Powertuner. Maybe the HPTuners just don't show that table to us. On my 04 Comp G, hell since I tuned the car to shift when I want it to then I never use Tapshift with it. On the GXP it still shift stupid until I get my tune so I'll still use the Tapshift function.
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