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View Full Version : Transmission shift feature during heavy throttle



PSWired
January 6th, 2005, 02:20 PM
I've been wondering about a feature that some Lexus cars have that might be possible to implement on a GM truck. When driving at WOT and the trans has downshifted to get the RPMs up, if you let off the throttle it will not upshift immideately, it will stay in the lower gear for a few seconds in case you get back on the throttle again. Would it be possible to add this feature to a new GM vehicle through the PCM tune?

GMPX
January 7th, 2005, 12:14 AM
I don't think so.

Sorry,
Ross

emarkay
January 7th, 2005, 03:39 AM
Wouldn't that just be a factor in RPM and MPH and vacuum and line pressure - I am sure something can be creatd to simulate this feature with the proper combination of shift point and other tunable params in the electronic transmission.

Can a "delay" (a loop or other thing) be programmed in to postpone transmission actions?

Now what about "Power" and "Economy" modes - I know some GM cars have that switch, and it must do SOMETHING to the PCM programming - anyone investigated just what 2 lines to close (or open) to enable this as a toggle switch?

Taking it further, how about while black box logging (for the next release model) have a input jack for a 3 way pushbitton switch. Switch centered for nothing, bump up to lock in current gear, bump up again to upshift, and the reverse for bump down. Great for dragstrips and those that like the automanual trannies on some cars, and could give a BIDI feature that is most important while dynoing easy access.

Comments?

MRK

GMPX
January 7th, 2005, 08:21 AM
Problem is nothing in the shift tables is time based, it's all RPM and TPS and MPH. You might be able to simulate it, but I don't think it would behave just like the Lexus trans, so I still say no it wouldn't behave like a Lexus.

As for your Power/Econ switch, just a momentary close to ground switch to toggle between the two on Blue connector pin71 (for 1999+), for the Camaro I think all you would need to do is add in some sane values in the power shift tables.
Of course you also need to know which mode you are in, that is a serial data message, so you might be in trouble there.

Paddle up/down shifts MRK, man, would you like an Apexi sticker with that :wink:

Cheers,
Ross

Brains
January 7th, 2005, 10:42 AM
:lol:

wait4me
January 7th, 2005, 01:13 PM
lol

GMPX
January 8th, 2005, 01:45 AM
'Zat one of doze riceburner wrong wheel drive thingies????


Yes, it's the must have add on for the ricer crowd, only Apexi do make some decent stuff, problem is the decal sales would out number real products 10 to 1 I'm sure.

Now, there was a place here in Aus that did a paddle shifter for the 4L60E, it looked rather crude though and was not cheap.

Of interest, out here the new GM QuadCam V6 has the option in the transcontroller for paddle up/down shifts. Well, for the new 5speed auto anyway.
http://www.holden.com.au/www-holden/action/modeloverview?modelid=4004

Cheers,
Ross