I hope someone has seen this problem. 2001 F-150 71000 miles., 5.4 liter 4R70W trans.
When shifting from park to revers the engine idle surges. 200-300 rpm approx. When going from reverse to drive 100-200 rpm. Doesn't matter if it is cold or hot. Except that the rpm is higher when it is cold. Had the pan dropped. There was some metal in the pan, and the mechanic said he felt a slight shudder on the test drive. I don't know how much is too much metal in these. But it didn't seem excessive to me. I just bought the truck. I do not know if the fluid has ever been changed. Probably not. Truck shifts fine in all other situations. Seems to have lots of power and pulls through all gears. Is this a trans issue or an idle issue?

Thanks to all who answer.

 

I would clean the IAC and see if that helps.

If there wasn't a yellow plastic bobber in the pan, the fluid has been changed.

Shudders can also be a low grade misfire.

 

Mine does the same thing. 02 with the same trans, though it's a reman. Fluid/filter are good.

I would guess it's normal.

Mine also bounces a bit going from 30mph to 0.

 

Thx, I will try that. Don't remember seeing anything in the pan beside the magnet.

 

Frank, I've merged your two threads on this subject. Please don't start duplicate threads on one topic because it can lead to confusing responses that waste everyone's time, including yours.

- Jack

 

Did you ever get to the bottom of this? Im seeing the same issue start recently. I have changed my trans fluid several times in 140K miles using the Motorcraft Mercon V so I dont think thats the issue. Im thinking some type of sensor is acting up.

 

I think this is your answer:
The IAC (Idle Air Control) is not part of the transmission. It is located on the engine throttle body.

 

Thanks Mark - I was wondering if a cleaning or replacement actually cured the symptom though as I would likely want to just replace it with a new one and move on:-)

 

I would at least try cleaning it first to see if it helps. If it doesn't help, then you need to start looking at other things. If it does help, then plan on replacing it sooner or later. It's very easy to get to.

 

I never solved it. I just have to wait until it idles down after the first start of the day to minimize the surging.

 

Thanks Frank, Did you clean & or replace the IAC at all? Curious.

Thanks Again!
ALR