Strange 3rd gear in '03 auto?

[bham_gt]

I have a 2003 Mustang GT auto. When the car is in 3rd gear at low RPM’s (around 35-40 mph) and you start to slightly accelerate, it is a bit jumpy and sort of bucking. It’s almost like it’s trying to shift into OD, but can’t make up its mind whether or not to shift. Once it shifts into OD, it’s fine and doesn’t do it anymore. Also, under hard acceleration, it doesn’t do it. Only when you’re barely on the gas. Third gear is the only gear I’ve noticed it in. Only mods are welded in mufflers and a K&N. It’s done this ever since I got it (it has 26K miles now, 16K when I bought it). Does anybody else have this problem or know what it might be? I’ve just assumed that it was normal, but if it’s something that needs fixing, I want to get it in before the warranty goes out. Thanks!

 

[02davestang]

I have this same thing happen to me in my car. my tranny went out about 2 months ago and it did it then.(don't think thats why the tranny went out tho) it does this now with a completly new tranny. i to am wondering why it does this. also, my g/f 2000 v6 with an auto tranny does this as well. i was thinking maybe it needed a flush and filter change, but i'm not so sure anymore since mine does it too. also sometimes i just turn the o/d off and it doesn't do this, but i don't do it all the time for fear of the tranny getting too hot. i need that dang tranny cooler in there!

 

[bham_gt]

...also sometimes i just turn the o/d off and it doesn't do this...

Yeah, I've tried turning off the O/D too, but mine still does it although not as much. Hopefully somebody will have some answers for us.

 

[prsrizdgt]

My opinion is that Ford has the computer shifting the car into OD too early. I think it should be up around 45mph, but for gas mileage they program it in as early as possible. I think this can be rectified with a custom SCT tune.

 

[propellerhead]

Mine used to make a sort of clunk sound when I was cruising lightly in 4th at 40-45 then I give it gas to accelerate. Ford told me it was the 4r70w switching from cruise mode to engage mode. It doesn't do it now since I got a custom tune that changes my part throttle shift points.

 

[back_in_black]

Mine used to make a sort of clunk sound when I was cruising lightly in 4th at 40-45 then I give it gas to accelerate. Ford told me it was the 4r70w switching from cruise mode to engage mode. It doesn't do it now since I got a custom tune that changes my part throttle shift points.

same with me, chip fixed problem and also was able to firm up shifts

 

[samishii]

I have a 2003 Mustang GT auto. When the car is in 3rd gear at low RPM’s (around 35-40 mph) and you start to slightly accelerate, it is a bit jumpy and sort of bucking. It’s almost like it’s trying to shift into OD, but can’t make up its mind whether or not to shift. Once it shifts into OD, it’s fine and doesn’t do it anymore. Also, under hard acceleration, it doesn’t do it. Only when you’re barely on the gas. Third gear is the only gear I’ve noticed it in. Only mods are welded in mufflers and a K&N. It’s done this ever since I got it (it has 26K miles now, 16K when I bought it). Does anybody else have this problem or know what it might be? I’ve just assumed that it was normal, but if it’s something that needs fixing, I want to get it in before the warranty goes out. Thanks!

Its the stock Torque Conveter. It does it in the AODE trannys. Same thing with mine.

 

[Dark Knight GT]

Its a number of things balled into one. However, if you only notice it at light throttle, its probably low torque levels that is resulting in the slower shift. Remember, the transmission operates off torque for the most part. The more torque it recieves(I.E. the more gas you give the car) the faster it will shift and disengage gears. It could also be that the fluid needs changed. Its common rule in these cars to change the fluid every 20-30k miles along with the transmission filter.