Had the batteries disconnected to do the alternator. Does that force a relearn on the tranny and maybe miss a shift or run the RPM to high? If it does go above max RPM, what happens...De fuel occur or like a gasser, run the risk of blowing an engine?

Any info appreciated!
Randy

 

Drive it....no problems...the PCM won't let you destroy it.

 

The PCM has an RPM limit flashed into it. The only way to go above that is to reflash the computer.

 

a runaway will do what it wants

it has a rev limiter but I am unsure of its conditions

why do you ask??

 

He didn't say anything about an oil leak, Benny. He will be ok.

 

After the batteries were hooked up, I installed my SCT street tune. Drove the truck a little to confirm the voltage was at 13.5 or more and the new alternator was good. Couple stop signs later, stomped it, swore I saw 4000 rpm at the shift but was so fast I couldn't really tell cuz I'm really watching the street. Tires were making a big black mark and I was going kind of sideways. As soon as I noticed I let off but at that point, to late.

 

4,000? You didn't even come close to the being worried stage.

 

Worry when you are at 6k or higher!

 

No but the Chevy guys were.......

 

I wouldn't go above 4500 RPM. The rods don't last long at 5K+.

 

I usually have pretty good luck a dredging up old posts but no luck in this case. A couple years ago a poster was discussing this same subject and talked me into checking out what my truck would do if I would start in 2nd gear and hold the skinny pedal to the floor. Yea I know, but I got curious and tried it. I don't remember the exact numbers but the truck ran up to something like 40mph-RPM's ramped up to maybe 4800 and after a couple of seconds it dropped back a couple of hundred to 4600 and everything just kinda hung there with the skinny pedal on the floor. It didn't seem to be painful to the truck just motored along smoothly. Clearly there's a governor function in the ECM. As posted above, it won't let you over rev.

 

The PCM has a defuel strategy that kicks in at 4000 rpm

 

That is what I was looking for. Kind of knew the truck wouldn't be hurt, hearing that diesels don't like much over 3500rpm, couple buddies have said this 6.0 likes RPM. Wanted a second opinion as there trucks have had engine repairs.

 

As stated in some above posts, the PCM probably doesn't actually prevent the rpms from exceeding 4000, but will cut fuel in an attempt to regulate the rpms - clearly Ford wanted to keep the rpms below that number.

 

The 6.0 does like RPM's. My previous engine went over 4K many many times. 4500 on the dyno. You'd have to run some pretty extreme tunes to hurt the bottom end on this motor