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Old 03-04-2012, 05:49 PM   #4
Rat Fink
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Delayed and harsh shifts can also be caused by things like throttle position sensors. In the old days, there was a throttle valve in the trans that increased "TV" pressure based on driver input (how hard they were on the gas). This offset governor pressure (which was responsible to open the various shift valves) and caused a delay in shifting when you were on the throttle (This is what caused the trans to shift at a higher rpm under heavy throttle as opposed to shifting earlier under light throttle).

In modern vehicles, the EPC solenoid is responsible for line pressure and is pulse-width modulated to provide boost as needed to the system (replaces the throttle valve in most modern applications). Input from the throttle position sensor tells the TCM how hard you are stepping on the gas pedal.

Honestly, its anybody's guess as to what is wrong with your trans without actually being there in person to test it. Personally, I would hook a line pressure gauge up to your trans and attempt to recreate the condition while monitoring the line pressure as well as monitoring a scantool for input from the TPS.

The harsh shift into drive, as well as hanging onto gears longer than normal tells me there could be something wrong in the "TV" circuit.
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