91FormulaKiller

iTrader: (28)

Have an issue on an S10 where if cruising in overdrive and the throttle is applied lightly until it initiates the downshift into 3rd it skips/slips and more throttle needs to be applied so it goes to a 4-2 shift for passing. Can anyone propose what the issue is? Not good with trannys. Thanks

mrvedit

This simply sounds like the 3/4 clutch is slipping. You aren't noticing it in 4th gear because by the time you give moderate throttle it downshifts into 3rd.

91FormulaKiller

iTrader: (28)

ok makes sense. I ended up talking with a transmission rebuilder (the actual builder of the shop) and he was telling me I should check engine performance first, which I will admit, it does have a misfire on cyl 5 from a bad plug wire that needs to be replaced but the bucking the truck does during that shift point seems more harsh than a simple misfire initiated problem.

mrvedit

The mechanic is pointing out that a bad engine sensor (especially TPS or MAF) could cause the PCM to not raise the transmission's line pressure enough to prevent slippage.
Hooking up a pressure gauge and monitoring it while driving is the best way to rule that out. (Search "ATD-5550" its $35 on Amazon)