Quick shifts off the line only at WOT
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From: Orange Park, FL
Quick shifts off the line only at WOT I've been having some problems at the track off the line. At the launch, the trans immediately shifts to 2nd then 3rd gear (litterally right off the line). It'll ride in 3rd for about 20 feet out then downshift to 2nd and go. It only does this off the line at the track at WOT. Part throttle shifts in city driving are fine. It honestly acts as if the tires are spinning (27" ET streets) but the rear end doesn't feel loose at all. Also I shouldn't be hitting 3rd gear at WOT until somewhere near 80 and my speedo shows no where near that MPH, nor does it drop down before it downshifts to 2nd as it would if the tires were spinning.
The trans is a built vacuum modulated 4L60E with a Yank SS4000 converter. I've messed around with the shift pressure modifiers with HP tuners, although I'm not sure if that's going to have any effect with the vacuum modulator installed. I basically took a stock Z06 vette tune and transplanted the shift tables onto mine. I haven't flashed the tune yet to test it out.
Has anyone else dealt with an issue like this before?
The trans is a built vacuum modulated 4L60E with a Yank SS4000 converter. I've messed around with the shift pressure modifiers with HP tuners, although I'm not sure if that's going to have any effect with the vacuum modulator installed. I basically took a stock Z06 vette tune and transplanted the shift tables onto mine. I haven't flashed the tune yet to test it out.
Has anyone else dealt with an issue like this before?
Are u tuned to ur stall? I know of a couple of people who werent tuned to their stall and from stalling their car up for to long time (stalling it up at the line) cause them to automatically shift into 2nd real early.
Watch the tps readings if you have the ability .
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From: Orange Park, FL
GT Griller - what exaclty do you mean by "tuned to your stall" ? I was set up on a different motor with a 3500 stall and was running great; pulling 1.60 60's all day. I then changed the motor, built the trans, and went to a 4000 stall. I retuned for the new setup by Mike Norris (Next Level Performance) and did some fine tuning myself with HP Tuners software (after my initial runs where I noticed the quick shift problem). I haven't made any changes specifically because of the change in stall speed, and I don't know of any changes that Mike made for the transmission other than some WOT shift point adjustments for the new setup (well above where it is actually shifting).
daniel6718 - It's actually shifting into 3rd gear, not locking into 2nd
Performabuilt - One thing I noticed that was a bit peculiar is that the TPS readings displayed in my Tech 2 never went above 99% in the transmission data. In engine data display, it showed 100%. The actual TPS voltage displayed in both engine data and transmission data was the same. However I wouldn't think this would make any difference because the PCM is programmed (according to HPTuners) to use the WOT shift tables anywhere above 93% TP. Aside from that, the part throttle shift tables are the same from 90% up.
daniel6718 - It's actually shifting into 3rd gear, not locking into 2nd
Performabuilt - One thing I noticed that was a bit peculiar is that the TPS readings displayed in my Tech 2 never went above 99% in the transmission data. In engine data display, it showed 100%. The actual TPS voltage displayed in both engine data and transmission data was the same. However I wouldn't think this would make any difference because the PCM is programmed (according to HPTuners) to use the WOT shift tables anywhere above 93% TP. Aside from that, the part throttle shift tables are the same from 90% up.
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Ok well was and idea I imagine your going to have to figure out the tuning then it about has to be there,
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Joined: Nov 2006
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Skinny im having the same problem as you. I have the same trans setup 4L60E level 4 from FLP vacuum modulator,did you find out what was causeing the shift problems. The only thing i changed was the heads, and cam now it shifts immediately into 2 then into 3 for about 20-25 feet then in 2 and pull like hell. My porgrammer is puzzled so am i any help would be great.