New member here.

I'm glad to be on board but I have a question.

I have a 1997 Ford F150 with a 4.6 and the tranny code is a U. The tranny seems to rapidly "bounce" in and out of overdrive at 1700-1900 rpm. Is this something that anyone else here has experienced and what did you have to do to fix it? Thanks.

 

Hi Tn Welcome!

When i first got my 99SC 4.6L a/t (4R70W) it did same thing.
I think same tranny in your truck. Apparently fairly common at the time...dont know about newer models?

After i installed the schip...it did change way a/t shifts...still drops out of o/d...just not as much. Check out computer bd.

Read/search what others have done to change way a/t shifts. Lots of info. here.

Good luck...OT

 

This sounds more like your truck is umlocking the torque converter. I'm assuming this happens on a slight incline. When you think your truck has shifted out of OD into 3rd push the OD button & see if it shifts down again.

If what I described is what is happening, don't worry...it's perfectly normal.

 

Thanks for the replies. It actually does the same thing if the overdrive is on or off. It does it when going up a slight incline. What concerns me is that I never really noticed it with this frequency over the first five and a half years or the first 40k miles I owned the truck. It seems to be perfectly normal other than this.

 

Okay, in that case it may be torque converter shutter. This was very common in the 97+ models with Mercon III ATF. It normally happens between 35-45 mph, but can happen at other speeds. The simple fix to this problem is to completely replace all the ATF with Mercon V. This will normailly clear up any TC shutter within a few hundred miles. I think this can be done with a transmission flush too, but I'm not sure.

 

The transmission codes are:

M — Manual, 5 speed, overdrive M5OD.
U — Automatic, 4 speed, 4R70W.
E — Automatic, 4 speed, E40D.

 

Thanks for the info, everyone.

 

If you're interested in changing the fluid yourself, this site could be a help.



http://members.shaw.ca/pferlow/transmission_oil.htm

 

Just asking for an opinion. I regularly change my own oil and spark plugs on different vehicles and other simple things. This fluid change with the torque converter drain procedure sounds a little more complicated however. I don't want to bite off more than I can chew. Any advice or opinions from someone who has done this previously?

Thanks.

 

If you can change the plugs in your f150 4.6 then you shouldn't have any problem with this. I can be a bit messy, but if you don't mind getting dirty go for it. Jack stands can help with the job, but I'll warn you, my '97 f150 4x4 has a cross member that prevented me from dropping the back of the pan first. Considering I had the front jacked up I thought gravity would help if I dropped the back first, but just ended up making a big mess when the fluid ran down the cross member to the frame.

Regardless, it's fairly easy, just be ready for a mess. The good news is if you do it yourself you know its done right.

And I almost forgot...DON'T use the cork gasket that comes with the filter! Reuse the Ford gasket.

Good luck

 

Try this method. It may be less messy.

http://www.ford-trucks.com/articles/...hangingatf.php

It covers the E4OD, 4R100, and 4R70W.

 

Is there no danger of damage to the tranny if you drain the fluid by using the engine to pump the fluid out with the tranny in neutral as described in the proceedure referenced by Mark?

 

If this guy is a "Ford Transmission Engineer" like he claims he is, there is nothing wrong with Mark's advice.

Great Transmission Info Here

After reading some of the info here, it seems like a good cooler is the single most important item for a tranny...