Gear at Speed Question: 7AT

Jordo!

Something I've found to be a little irritating about the 7AT, which I am otherwise extremely pleased with.

I notice that 4th gear appears to be very particular regarding road speed and RPM -- that is, on coast down, the ECU is especially picky about being in 4th vs. 3rd.

Put another way, I invariably down shift at the correct engine/road speed, and thus am not beaten to the down shift on coast down by the 7AT.

The one exception is 4th gear. 2nd, 3rd, 5th and higher all seem to allow one to coast down to very low speeds without initiating an automatic down shift to prevent stalling.

It's not a big deal, but occasionally I will miss the downshift at low speeds, and if I fail to drop a cog at about 1900 RPM, the ECU may beat me to it, and suddenly I am in 2nd, revving higher than is needed.

Is there a specific mechanical reason why 4th is very picky? Are 3rd and 4th just especially close.

Anyone have any thoughts on this, strictly from a mechanical standpoint?

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NickTurnon

I have no insight on the mechanical portion of this topic...

But I can say, that my 4th gear hangs its RPMS even when I let off the gas longer then my other gears.. Like you mentioned, other gears let you coast and 4th gear just wants to play.

You think the ECU is programmed to make 4th the "picky" gear because theres a huge amount of power in that gear?

I personally think 4th gear is the best gear on this 7AT.. On the freeway- with my exhaust- its perfect!

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Tazicon

Just down shift sooner.................I have never experienced this issue with mine. I am always in Manual with it. One thing though I have an CBE on mine and I love the sound so I probably down shift early anyway.

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Jordo!

4th and 5th are great cruising gears, but downshifting to 3rd at, say just over 2K initiates a throttle blip whereas and just under it's perfect -- at least based on my style of driving.

On throttle at lower speeds 4th will be okay, but throttle off even for a second at low speeds and it will insist on being in 3rd gear, which may mean accidentally dropping to second -- too low a gear.

It's an infrequent issue for me, and not the end of the world, but it strikes me as a bit of design or tuning flaw considering the comparatively wide practical range of use for the other gears (except 7th, which is pointless unless highway cruising at sustained high speeds.)

3rd gear is perfect for slow residential streets where you go over speedbumps and the like -- it will just hold the gear and have plenty of grunt to get moving again.

I wish we could turn off the automatic down shift with UpRev. Be interesting to see whether or not the engine would really stall out if it were left in 4th at the "wrong" speeds. 4th is kind of a limited gear with a narrow range of practical use it seems.

I'll have to compare gear ratios -- I bet 3rd and 4th are just a little too close together or something.

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danelonson

FPenvy

i agree with nick.

4th just seems to have some serious pick up when cruising. usually my freeway/highway entrance gear unless its a tight turn where 3rd is needed due to slower speed.

as for the downshift from 4th to 3rd i havent really noticed it on mine in awhile. when i first got my car i got caught double downshifting into 2nd because of the OP's problem. now though i feel my ECU, TCM, and me are on the same page. 4th doesnt downshift on me anymore like it used to.

also i will say i had my TCM tuned for stronger shifts but no clus if that would effect OP's problem.

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324whp/258wtq AAM Tuned |F.I. NonRes CF CBE/NonRes TestPipes #373|UpRev Tuner|Akuma Motorsports Intakes|Z1 34 Row Oil Cooler

FPenvy

1 - 4.924
2 - 3.194
3 - 2.043
4 - 1.412
5 - 1.000
6 - 0.862
7 - 0.771

R - 3.972

FD - 3.357

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324whp/258wtq AAM Tuned |F.I. NonRes CF CBE/NonRes TestPipes #373|UpRev Tuner|Akuma Motorsports Intakes|Z1 34 Row Oil Cooler