Greetings everyone!

I have a 2002 F150 5.4 SC...with a chute. Well, it feels like a chute.

This started happening the other day. I am driving around 65 MPH at around 2kish RPMs. When I let off on the accelerator the truck "coasts" at 2kish for a little then the RPMS drops to around under 1k...thus feeling like a parachute just opened in the back.. or if you had a manual trans, put it in 4th and slowly let out on the clutch at 65.

I CND this everytime but it seems to happen more so when its warm out (I live in Oklahoma.. it can be 75 one day, 35 the next). Does anyone know what is going on with this or have ever experienced it before?

 

Try putting it in neutral and coast. If it still drags then its transmission. The converter input assembly has a one way clutch that can have a fault that makes it lock up even though you would be in neutral.

 

Thanks, Bluegrass.

I'll try that this afternoon on the drive home (if its acting up). Obviously the trans is dropping out, thus letting it goto a much lower RPM, but would 'nuetral' cause the 'drag'? It doesnt seem like it would.

Anywho.. will give it a try and post an update.

 

Well darn. I CDN this afternoon do to highway construction! eeep!

Will try again in the morning!

 

I'm going to throw something out here for everyone to ponder!

I think that part of the pcm's learning curve is to cycle it into and out of "open and closed" loop operation for the first few driving cycles after it has been cleared, either by battery discount or reset by a code reader.

With that in mind, have you disconnect'ed your battery lately?

Is it possible that your battery is getting weak and the pcm is resetting on start-up?
Do your guages (speedometer & tach) do a full sweep at start-up? That's a sign that the pcm is being reset?

The reason I bring all this up is, I have a SuperChips custom tune in my truck and when I switch between custom and stock tunes the pcm gets reset and when it's in it's learning cycle I have the same thing happen for the first 30 or 40 miles and have noticed (by my scan guage it going open and closed loop operation) then all is fine.

Going from open to closed loop operation does lock and unlock the converter.

But in your case if the pcm's getting reset on every start it's always in it's first learning curve.

Just for what it's worth! And to get the idea juices flowing.

Gene

 

Gene:

I think that is exactly what has happened. I did disconnect my neg terminal the other day while I cleaned my IAC. I havnt been able to duplicate it again since it happened Tues. afternoon.. but again, I havnt been able to travel at 65 again do to contruction lol!

EDIT:

But I did want to mention that my gauges do sweep everytime I turn the key over.. Well, they did this morning.

 

Had cold weather the oter day and I noticed that my truck was making a full guage swing when started, I had the battery teasted and was ony making 245 cold cranking amps. If the battery is low enough to make the guages swing it could possably erase the computer memory. I installed a new 850cca battery and is fine now. That low of a battery can't last long and also is very hard on the starter.

 

I don't always word things right and don't it clear sometimes.

But Chucks bp is right! The guage sweep means just that "the pcm has done a reset" because the battery voltage was low during engine cranking. And that is a sign of weak battery or poor connection to the posts!

Good luck and it's been what, three years on that battery anyway! It proably living on borrow'ed time and needs replacing.

Gene