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Shift by RPM instead of MPH

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Old Nov 6, 2008 | 08:39 PM
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Default Shift by RPM instead of MPH

Just wondering if you can have the car programmed to shift by RPM instead of MPH? That way you could run 28" tires at the track and 26" on the street without any shift point problems.
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Old Nov 6, 2008 | 09:23 PM
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I could be wrong, but i believe shift points are always calculated by RPM. I know in efi live, when you move the shift point, you change rpms, not mph.
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Old Nov 6, 2008 | 09:32 PM
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Thats what I have mine doing..

So instead of the car having to meet the two commanded requirements, MPH & RPM to shift, I lowered the MPH really low so it always meets that requirement and just set it to shift at the desired RPM.. Its been flawless ever since.

Only thing I noticed was when I data logged a pass, the data on teh shifts were all wacked. It says I shifted into 4th at 68MPH and skipped 2nd gear. But, I know its not true as I ran a 10.71 @ 126 mph.
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Old Nov 6, 2008 | 09:34 PM
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WOT shift points are governed by rpm, part throttle by vehicle speed. Since at the track you'll only be going WOT, you shouldn't have a problem.
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Old Nov 6, 2008 | 09:42 PM
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Okay, so I could run taller tires and not have to worry about shift points at the track? Is that also true for LT1s?
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Old Nov 6, 2008 | 09:57 PM
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Originally Posted by RevGTO
WOT shift points are governed by rpm, part throttle by vehicle speed. Since at the track you'll only be going WOT, you shouldn't have a problem.
You may be right but why do the tables below have to do with it? In EFILIVE it says this under "parameters". I have mine set at 3-8MPH so I know this has been met and use the rpm to shift..

{D0910} WOT 1->2 Shift Speeds, Normal
{D0911} WOT 1->2 Shift Speeds, Performance
{D0912} WOT 1->2 Shift Speeds, Hot
{D0915} WOT 2->3 Shift Speeds, Normal
{D0916} WOT 2->3 Shift Speeds, Performance
{D0917} WOT 2->3 Shift Speeds, Hot
{D0920} WOT 3->4 Shift Speeds, Normal
{D0921} WOT 3->4 Shift Speeds, Performance
{D0922} WOT 3->4 Shift Speeds, Hot

Which is WOT and wanting a certain speed.
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Old Nov 6, 2008 | 10:37 PM
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I don't know what the interface is exactly between that table and the WOT RPM shift table, but IIRC, this is how it works: the 100% throttle mph in the part-throttle table must be less than that of the WOT mph table for it to shift properly.

When the WOT rpm setting exceeds the WOT mph, it shifts by rpm. That's how it's programmed from the factory, so de facto it shifts by rpm at WOT.

You'll notice when you log that the mph of your WOT shift exceeds the figure in the WOT mph table.
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Old Nov 6, 2008 | 11:24 PM
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Originally Posted by RevGTO
I don't know what the interface is exactly between that table and the WOT RPM shift table, but IIRC, this is how it works: the 100% throttle mph in the part-throttle table must be less than that of the WOT mph table for it to shift properly.

When the WOT rpm setting exceeds the WOT mph, it shifts by rpm. That's how it's programmed from the factory, so de facto it shifts by rpm at WOT.

You'll notice when you log that the mph of your WOT shift exceeds the figure in the WOT mph table.
Yea, I have it set from 3pmh-8mph so its sees it right from the beginning.

Mine might be a little different as its a vaccuum modulated FLT 60E.. I had a question about my N20 data logged pass a month back. The shifts it was saying does not match to my ET.. See here.

https://ls1tech.com/forums/automatic-transmission/1006020-data-logged-my-n20-pass-question-about-converter-trans.html
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Old Nov 7, 2008 | 08:16 AM
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I had a problem with corrupt data in my log files. I posted on EFILive Forum and was told to "Reprogram the PIDs into your V1 after first entering your correct VIN and OS."
When I checked the scan tool, it was showing correctly at the bottom of the page, but when I opened the VIN window, the OS box was blank. I fixed it and end of problem.

A friend had a similar problem and it showed his WOT shifts at 4000 rpm. Yet we were running neck and neck at the track and my shifts were showing right on. After adjusting the scan tool, it showed his tranny was behaving properly.

So, given your times, I'm quite sure your transmission was shifting normally; your log data is corrupt.
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