F150 5.4 vs. Navigator 5.4
#1
10-08-2005, 11:05 AM
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F150 5.4 vs. Navigator 5.4
I have both. The F-150 specifies 87 octane regular fuel, but the Navigator requires 91 octane premium. Anyone out there know the specific reason why? I think it may be the factory tune, but I am extra curious... the engines seem to be identical, both are 3V 5.4L, although the intake duct on the Nav is totally different than the intake on the King Ranch. I sure wish the F-150 had the 6-speed tranny - the Nav get's better mpg than the King Ranch!
#3
10-08-2005, 11:30 AM
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this is what i posted in another thread a while back as to why i only run regular in my navi.
There is a normal section of data in the PCM for controlling timing advance. Then there is another, alternate table that has advanced curve rates (up to 7 degrees extra). If the vehicle even uses data from the knock sensor ( some, including a 99-04 lightning, do not even have the capability of making changes based off the ks) then it will use values from the alternate table as long as the voltage on the return of the ks stays below a certain level. The vehicle will perform just fine using the standard timing tables though. Even if the engine was detonating significantly, the PCM cannot "retard" the timing any past the base table values. And 7 degrees of timing at cruise makes little to no difference in fuel mileage.
Last edited by kidtriton; 10-08-2005 at 11:38 AM.
#4
10-08-2005, 11:58 AM
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Many Thanks!
Thanks for this info - the PCM is much smarter than I realized! Do you suppose the F-150 PCM is programmed the same way, and thus would benefit from the use of 93-octane fuel with the factory tune; i.e., can the F-150 use the alternate advance table if the knock sensor detects no pinging with max advance from the primary advance table? 
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10-08-2005, 01:00 PM
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Originally Posted by Texas Wolf
Thanks for this info - the PCM is much smarter than I realized! Do you suppose the F-150 PCM is programmed the same way, and thus would benefit from the use of 93-octane fuel with the factory tune; i.e., can the F-150 use the alternate advance table if the knock sensor detects no pinging with max advance from the primary advance table?
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10-08-2005, 01:50 PM
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#7
10-08-2005, 02:13 PM
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10-09-2005, 01:03 PM
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#10
10-27-2005, 09:47 AM
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I have an 05 F-150 and a 99 Navi. I use 87 in both and both run great. When I bought the Navi new in 1999 I used super 93 for the first 4 years and then switched to regular (after heads were replaced) and cannot tell a difference. Can you beleive I had both heads replaced on that thing at 70,000 miles due to carbon build-up. Ford said it was a problem they were aware of and I paid $600 and they covered the rest $5500!
I also have a Mustang GT 1990 I bought new in 1989 and now has a 331 stroker, Just thought I would share that
I also have a Mustang GT 1990 I bought new in 1989 and now has a 331 stroker, Just thought I would share that
Last edited by F150--FORD; 10-27-2005 at 09:49 AM.
#11
10-27-2005, 10:13 AM
When I bought our 2000 Expy, new, the salesman told me to run 87 octane only as any thing higher would run the risk of damaging the sensors. Was this true or BS? I have always used 87 octane and it runs great, of course, it only has 7800 miles on it. It is my wifes car and sits in the garage most of the time.
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#12
10-27-2005, 05:43 PM
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Thats a load of crap. Running a higher quality fuel will not only not hurt sensors, it will probably prolong their life due to the cleaner burning nature of premium fuel. I burn premium fuel in all my vehicles. When I run fuel injection cleanings on them, they never smoke or have any other effects of a system that is carbon slathered.