Hello,

When my 2006 F250 with a 6.0 was newer, I could hit a top speed of around 95. Now with 155k miles, it tops out at 81 with a fair amount of pedal left. What happened?

Thanks,
Bill

 

We need more information if you want answers.

 

Don't know what else to say. The truck used to hit 95-96 MPH when it was new, now it tops out at 81, 82 if going down hill. I have not done any mods to it.

 

Could be a fueling issue, could be a high pressure oil limitation, etc.

Do you have an OBDII scan tool that reads engine parameters?

If you don't have one, then a smart phone can get you one (download ForScan lite and buy the ELM327 OBDII device appropriate for your phone - Bluetooth or WiFi)

 

Thanks. I do have a scanner, and will check into it. I have had the dummy plugs replaced on both sides, guess it could be related to that.

 

 

Mark just out of curiosity what is the governor set at?

grelch Getting something to read live data with the 6.0L is vital for diagnostics. In fact that is true with any of the modern vehicles do to all the electronics and
particularly the drive by wire ones like the 6.0L. When I say drive by wire in our case the throttle and trans are both controlled electronically. Yes you can override
some of the trans shift controls but not all of it. Then you have all the modules that talk to each other and effect each other. To get a good idea what is going on
you need to be able to read that data in a form humans can understand.

The tools to do the job vary from the low cost to the very expensive and the funny thing is some of the low cost tools can do a very good job.
One word of cation with the ELM devices. You want to avoid using the included software they come with. The word is you get a lot of malware
and other types of adware. The better packager to use with them are the Forscan and Torque. There may be others that have not been looked at yet.
If you want to go high end they your into the Snap On and Ford VCM2 tools. The Autoenginuity.does not read the 6.0L injectors all that well and
that is a big drawback with it. With it's price you can buy one of the China clones and do much better.

 

Defuel at 95 mph: PC/ED manual - page 1-15 (81 mph for F450 and F550)
Defuel at 4000 rpm's : PC/ED manual - page 1-13
Damage can occur at over 4200 rpm

 

Thanks Mark. I guess I should of just looked.

 

I just copied and pasted from my spreadsheet ..... that is the only reason for the PC/ED reference!

Re-reading it, including the PC/ED reference might have made it look like I was implying for you to look it up. I certainly wasn't. I have easy access to most of that stuff and don't mind posting it!

 

No, I was thinking your looked it up and was letting me know where is was found.


After having noes nose in way too many FAA reg books it can help to get a
little pointing on where something is hiding.