Posted: Sun Mar 07, 2010 11:07 am Post subject: Poor 1-2 shift under heavy throttle
The car is a 2000 Impala 3.4L with 128K miles. At 115K miles the transmission failed after a dealer service (transmission flush) and a used transmission was installed. If driven “normally”, the transmission works well, 1-2 shift at 20-25 mph, 2-3 shift at 30-35 mph 3-4 very smooth (hard to notice) at 45mph, torque converter lock-up seems fine at 60 mhp under light load. All down shifts are smooth. All upshifts are less than 0.5 second and seem to work well.
Under heavy acceleration “aggressive driving, heavy accelerating on highway on-ramps” , 1-2 gear shift seems to “hang”. 1st gear accelerates to 40-45 and transmission seems to be trying to shift but hangs in 1st. The transmission shifts into second only if I let off the throttle. Once I back-off the throttle the transmission shifts , there is no bang or harsh up shift, and seems to work normally after that point. That is 2-3, 3-4 shifts.
Transmission was service at 120K miles with a fluid flush and AMSOIL transmission fluid. Fluid looks good, not pink, a little orange and no burnt smell.
I don’t want to put another transmission in this car and could probably drive it normally for a lot of miles. Problem is, I keep it around for my teenage son to drive and he has a heavy foot so I am interested in getting it fixed, or at least preventing transmission damage.
When the transmission was replaced, I don’t know the mileage, year or vehicle it came from. I read a lot about reprogramming the PCM and I am sure this was not done by the dealer after the transmission was changed. BTW, there are no check engine lights and the transmission does not slip in any gear.
In your experience could this be a PCM reprogramming issue, Pressure control valve, solenoid problem, clutch problem or is this transmission just on the way out.
Your opinions please,
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