1998 Z28- doesn't downshift to first at WOT below 20mph
#1
1998 Z28- doesn't downshift to first at WOT below 20mph
Basically what it says, if I allow the car to get a second gear or higher it doesn't want to downshift back to first gear when I punch it. Sometimes it even does it at 30 miles an hour or so but almost always At low speeds. Otherwise transmission has seemed completely fine
Anyone know what's up?
Anyone know what's up?
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Basically what it says, if I allow the car to get a second gear or higher it doesn't want to downshift back to first gear when I punch it. Sometimes it even does it at 30 miles an hour or so but almost always At low speeds. Otherwise transmission has seemed completely fine
Anyone know what's up?
Anyone know what's up?
First, you mentioned in your other thread that you've done a wheel swap that has significantly changed tire diameter, causing your speedometer to be off by 5-10mph. This will also affect shift points, so I wouldn't worry about diagnosing any issues with shift points until first getting the speedometer corrected for the the current tire diameter.
Second, there is something odd in this regard that has occurred with every A4 LS1 F-body I've owned. Right around ~31-33mph they often don't want to downshift to 1st at WOT, but they will at lower speeds AND slightly higher speeds of 34-37mph or so. Now, this odd gap in downshifting is something you'd only notice on a 2.73 geared example because the 3.23 cars won't downshift to 1st above 29/30mph with the stock tune. However you can raise the downshift points via tuning (to 35mph for example), after which the 3.23 cars will experience the same gap/failure to downshift in that specific ~31-33mph range, even though they'll have no problem downshifting to 1st at ~34-35mph or at ~30 and below. It's not model year dependent either, I experienced this with my '98, '00 and '02 cars - also with stock and aftermarket built 4L60Es, stock and non-stock torque converters. Seems to be something inherent with their design/operation rather than any sort of mechanical failure.
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there are parameters in the tune that have to be met for both up and down shifts basically there are "windows" where shifts can happen if rpm & speed are both met , of course like rpm ws6 is saying if the rollout is different on the tire (taller or shorter than stock) things can get pretty crossed up.
Toss some stock sized wheels/tires on it to see if it still does it. you can easily change tire size enough to get the same effect as swapping gears a size or 2 323 to 342, 342 to 373 etc...
Toss some stock sized wheels/tires on it to see if it still does it. you can easily change tire size enough to get the same effect as swapping gears a size or 2 323 to 342, 342 to 373 etc...
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