WOT Shift Issue
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From: Marysville, WA
WOT Shift Issue I didn't get any response in the PCM section, so maybe one of you tranny guys has an opinion. I finally got around to logging a WOT run after my Yank SS3200 install. I only picked up 2/10ths at the track, ALL in the 60', and I lost ~ 2mph. So I knew something was amiss. Anyway, what I found was this:
I have the car set to shift @ 6700 in all gears, Rev Limiter @ 6800, but the car never hits that target. It shifted at 6500 1-2, and at 6200 2-3. The 1-2 shift hit the MPH limit, so that probably explain that (more later) but the 2-3 was 6mph under the shift point, so that one really puzzles me. I wound it out in 3rd & it shifted again about 6500 rpm.
EVERY table is set to make it shift @ 6700rpm, 37mph 1-2 (I'm raising that to 39) & 72mph 2-3. So what gives? I can't imagine it's the converter. Or the vacuum modulater mod we did. All I can think is that I need to do the SD tuning & re-scale my MAF tables accordingly. (actually, a friend - Racehead - thought that might be my problem).
Any ideas? I need some help if I'm going to hit an 11 sec cam-only 1/4 mile (I'm at 12.29 now)
Thanks!
Mark
PS The tranny was gone thru....new clutches, servos, band, planetary....all GOOD stuff. And my shift point selection was derived from dyno runs. It peaks around 6300 & holds steady to 6700.
I have the car set to shift @ 6700 in all gears, Rev Limiter @ 6800, but the car never hits that target. It shifted at 6500 1-2, and at 6200 2-3. The 1-2 shift hit the MPH limit, so that probably explain that (more later) but the 2-3 was 6mph under the shift point, so that one really puzzles me. I wound it out in 3rd & it shifted again about 6500 rpm.
EVERY table is set to make it shift @ 6700rpm, 37mph 1-2 (I'm raising that to 39) & 72mph 2-3. So what gives? I can't imagine it's the converter. Or the vacuum modulater mod we did. All I can think is that I need to do the SD tuning & re-scale my MAF tables accordingly. (actually, a friend - Racehead - thought that might be my problem).
Any ideas? I need some help if I'm going to hit an 11 sec cam-only 1/4 mile (I'm at 12.29 now)
Thanks!
Mark
PS The tranny was gone thru....new clutches, servos, band, planetary....all GOOD stuff. And my shift point selection was derived from dyno runs. It peaks around 6300 & holds steady to 6700.
It should have nothing to do with SD mode, maf just affects shift pressure, but not rpm at wot. I'd keep bumping up the rpm an mph untill you get your desired shift pt. I've found the pcm to be very much like a woman, you can't trust it and you'll have to mess around with settings to get it to do what you want. lol
Joined: Nov 2003
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From: Wichita KS / Rancho San Diego
Originally Posted by WAHUSKER
What? A table that doesn't do what it implies? Say it aint so.... Actually, I never thought about it being that simple. I'll go try that.
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From: Marysville, WA
Originally Posted by RevGTO
I noticed my 1-2 shift has dropped off about 200rpm since installing the converter and others have had the same experience. I don't know of anyone who has explained why.
Anyway, I think I may have found part of my problem. (the above may be the other part) I measured my Nittos & they are 25.6" tall, where my GSCs are 25.25" tall. And the custom Predator tune set my gear ratio at 4.10 - correct if I had a 10 or 12 bolt, but a 9" has 4.11 gears. So changing all that in the speedo tables moved my numbers about 5%. I'll bump the shift points up a tad more & hopefull call it good.
