When leaving home on a cold day my truck will not lock the converter for 2 or 3 miles and when you step on the skinny pedal the rpms go up and to somebody that doesnt know whats happening it could seem like its slipping. I highly doubt the OP drove hundreds of miles with a slipping trans. And with no od light flashing and the truck still going strong I think Marks answer is probably the most logical.

 

DOH!

My name happens to be Mark too. Maybe there's a trend.

 

Oh come on and not buying it, sorry couldnt resist either..

 

Now that right there is funny

 

Sounds like you and the OP have the same problem. That's just not normal. Maybe normal to your vehicles but not something Ford intended.

In my amateur racing days, people used to throw synthetic expensive fluids into everything. Don't get me wrong, I really don't want to get into the merits of synthetic fluids. But I think some people make a mistake not going with the regular old stuff Ford recommends. I know from experience, for example, that some synthetic fluids in a manual trans will really mess up the synchros and cause you to grind every gear. I know this is about automatics and torque converters but its possible the guicci fluid is adding to the problem.

 

I've now lost track of who said what and who is an engineer and who knows anything

Sounds like we have two former transmission engineers or builders. Lets let them duke it out.

 

No we only have one Mark K, Not sure how many fords you have had but both my f150 and my superduty need to come up to a certain temp before the converter will lock up and yes that is by design from Ford.

 

I don't agree Mark. My Excursion as well as lots of other vehicles I've driven do the same thing. By not locking up the torque converter generates heat which helps the transmission to warm up faster. Completely normal and they are programmed to do that. My point is only that I've never seen this last more than a few minutes before.

 

So says the voice with no knowledge of how this system works.

When did you work at Ford in Automatic Transmission Engineering? I was there from 1988 (at the very start of electronic transmissions) until 2007. I helped design a lot of the software running these transmissions. I even have one US patent (Click to read my patent) from software design.

I can tell you with 100% certainty that you have no clue what you are talking about. You're spouting off here and just showing your ignorance. You have no idea how the software works, but you do have your uninformed opinion on how YOU would design it. You're wrong.

I've known many auto trans mechanics. Most of them know A LOT of automatic transmissions. Almost none of them know much, if anything, about the software that operates the transmission. You're clearly in the category of not knowing the software. If you did know the software you'd know that the torque converter DOES NOT LOCK UNTIL THE TRANS WARMS UP.

There is one former auto trans engineer that worked extensively with the software and tunes that control the trans for 19 years. There are others here that have NO IDEA of what they are talking about that know THEY wouldn't calibrate the torque converter to not lock cold.

Now that I got that off my chest, I still think this is the torque converter not locking when it's cold. That is the way we designed it to work and there is nothing to fix. If I'm wrong, and that is possible, then there is a slipping clutch. It is easy to check for a slipping clutch. Pull out the transmission dipstick. If the fluid is nice and red there is NO slipping clutch. If it's brown, there may be a slip. If it is black then I'm wrong and there is a clutch slipping.

The fluid will turn black in less than 10 miles with a slipping clutch. Often within ONE mile.

 

I never said it didn't lock up until it was warm, and that makes sence because the action in the converter before locking up is beneficial to warming up.

 

I doubt if the fluid is the problem here and most people don't realize the brass syncros are actually a clutch that slows the opposing shafts down to equal speed to they can mesh so nothing more slippery is needed in the manuals.

 

Mark is an engineer not a hands on mechanic and they both have their merits.

 

I guess I'm just going to be happy that my transmission doesn't slip or not lock the torque converter or whatever. It works great outside the design spec.

 

I just realized something. All the experts on this thread that are busy throwing their weight around could all very well be right about transmission designs but funnily enough, they are all arguing about something that the OP might not be even experiencing. I said this earlier but this is pretty much impossible to diagnose based on the poor OP trying to explain a symptom in a forum like this.

You guys can keep reminding us of your expertise, which I do respect (your expertise that is, not the reminding) and I'm still going to say the OP should get his transmission diagnosed if he's worried about it. Then he can come back to this thread and enlighten us all on the results.

 

Both, actually. I've never been a professional mechanic, but I do a lot of mechanic work. I also owned a repair shop for a couple years, so I do have a lot of mechanical experience.

I do agree that both have their merits. I've worked with many professional mechanics, and most of them would tell you that they liked working with me because I listened to what they had to tell me, and respected their knowledge. I often leaned on their knowledge where mine was lacking.