recalibration???
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Joined: Sep 2010
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recalibration???
i have a 92 f-150, 4x4,supercab when i bought the truck it had 31 inch tires. over time i've gradually gotten bigger until i got to 33's. the question i have is. can running these bigger tires cause performance issues? i know it will throw the speedometer calibration off. but can it cause my truck to hesitate or pull back when going up hills or accelerating. does this model truck have a computer that would need to be reprogrammed for larger tires? it has the e4od tranny. i've noticed that it doesnt pull back as bad when i turn overdrive off. i have the 351w engine. my mpg is around 11mpg. is that normal? seems like it should be higer with efi. could i possibly have a tranny problem? any info or help with this is appreciated.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
Running that size tire is gonna have an impact on MPG. Also what gearing do you have? That makes a big difference as well. Some other posters can chime in and they will give you a more detailed view of tires vs. mpg vs. performance.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
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From: Kentucky
The computer is making decisions based on a specific tire size. Now that you have changed one of the parameters the PCM needs a corrected speed input. The PSOM needs to be updated with a different calibration constant to compensate for the larger tires.
Here is a writeup from another forum: What's a PSOM & how do I "P" it???
Thanks to Steve83
Here is a writeup from another forum: What's a PSOM & how do I "P" it???
Thanks to Steve83
Junior User
Joined: Nov 2009
Posts: 94
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From: The boonies of NH
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Ak Ford Man
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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Feb 4, 2011 12:42 PM
