another question for the pros!

ok what happens or what are the symptoms when your overdrive goes out?

Mine does all that sputtering and stuff when the over drive button is engaged.



THanx again

What? I have NO idea what you're trying to say/ask here. A little better question and description of what's going on will help tremendously.

Do you even know what the overdrive is?

Maximum Overdrive!

So when ovedrive is on it acts weird? Overdrive conserves gas it is a different gear for 5th so it helps mostly on highway, i think it also tells the tcu to shift sooner. If it only does it when it's on leave it off or vice versa.

actually overdrive makes the gears longer. If your driving at lets say 70mph at 2900rpm with the over drive on and the turn it off without changing anything else your rpms will go up to like 3400. Thats all it does nothing special just makes the gears longer

Overdrive isn't another "gear". It's a clutch inside the torque convrter that when locked in, prevents any slippage, which improves fuel economy and lowers the transmission fluid temp. As far as the "sputtering", i'd say it's a misfire during high load situations. Changing the plugs, wires, distributor
cap and rotor (or coil pack) should fix the problem.

I didnt say it was another gear I said it acted like it. And in some situations it is another gear like with an external over drive on a rwd application.

Overdrive is not simply a locked TC, though the TC will typically only lock while in overdrive, since it needs to be unlocked to shift. In more modern transmissions the TCU will lock the TC in other gears as well, and automatically unlock it for shifts. My dooley for example would lock in 3rd and 4th. The newer models could lock the TC as low as second gear.

In most cases of 4 speed autos, there are only 3 "gears" provided by the planetary gearsets. Overdrive is an additional mechanism that provides further output rpm multiplication (less torque multiplication). It uses a seperate clutch band, that can often fail (usually from people doing a lot of city driving with OD engaged, so it shifts in and out OD constantly). When this clutch is failing, it can surge a bit as it slips/grabs. If it's acting strangely when the car is going to slow to engage OD (usually around 45 mph or so) then something else is going on, probably with the TCU or something, but this is all well out of my personal eperience/knowledge.