I had not used premium fuel in my truck for more than a year but about two weeks ago I decided to try it again. I got so tired of the pinging and rattle my engine makes under acceleration that I decided to use the higher octane to see if it would stop. It did. On take off and when passing my engine is now smooth and quiet, no rattles at all. It seems to have an extra bit of oomph when passing, or is just wishfull thinking? One thing I have noticed also, the gas mileage went down a bit. I have a 97 with the 4.6 with 155, 688 miles on it . Anyone out there with a similar problem?

 

I have a '98 F-150 with the 4.6L and 99K miles. I have almost always used premium fuel. My truck will clatter and ping on anything lower, and I've noticed it does it a slight bit on premium when under hard accel. As far as performance increases, I never felt any difference in relation to fuel grade. I don't know if there is a solution to the clatter. I don't have much contact with any make other than Ford, but almost every vehicle i deal with seems to clatter on regular gas.

 

Try cleaning tha mass-air sensor first. ALso replace the fuel filter. It sounds like a lean condition.

Jimmy

 

Ford says to use 87 oct on "our" truck.....and I do and have never had any problems.
If you are getting pings or knocks then you have something else wrong. Do not use a octane different from what ford says.
I have heard many "expert" technitions says that high oct does nothing for gas mileage at all and I believe it.
The only time to use it is if you go to a high performance chip or something like that but not as a standard day to day fuel.

 

hello! as far as using prem fuel it is a waste. unless you have advance timing or higher compression. 87 should be all you need. small amount of pinging is normal if your getting heavy pinging try some high quality fuel injection cleaner to clean the piston tops.
as a side note all grades of fuel have the same additives. the octane rating is the ability of the fuel to withstand preignition (ping)
please save your money for fuild changes!

 

i've been running nothing but 89 octane in my truck...i've seen what 87 octane can do to a motor...after 100k miles running that crap and you tear it all down you will see what i am talking about...it messes up your valves, pistons, pretty much gunks up most of your internal parts and leaves carbon deposits that cannot be scraped off! not to mention 87 is a mix of basically anything they can get just to make it combustable! i have also noticed tons of water from the tailpipes when i use 87...not as bad with the 89 and my vehicles seem to run much better on it...

you guys wanna talk about pinging/knocking and compression? my 87 buick grand national can't run on anything LESS than 93 octane and that's the bare minimum! usually i run 104 unleaded if it's on the street or 116 leaded if on the track

 

That's true on the Buick. Turbo motors have very high cylinder pressures under boost. It's like running 13.0:1 compression.
A 9.0:1 compression engine should not require anything other than 87 octane. I have towed over 6,000lbs in 98 degree weather running the a/c on 87 octane in my 01 with the 5.4L and have never had a pinging problem. It is being caused by either a lean condition or carbon build-up in the cylinders.
I too run 93 octane in my 5.0 Stang, but I run the timing jacked way up which is good for 20 more horsepower on the dyno. If I back it back down to under 12 degrees initial, it runs fine on 87 octane.
Oh and leaded fuel will foul the injectors over time, but I'm sure that you don't use it enough to hurt anything.
I always use a bottle of good injector cleaner at every oil change. The Stang has over 156,000 miles on it and I have never had a fuel related problem with it.

Jimmy

 

Agreed, I think what will cause problems with an engine is a LACK of good oil.
I have always used what ford states.....5w30.....castrol and my engine is running as strong as ever with 180000 miles on it and still going.....and that's in arizona where it gets 115 degrees.

 

It's classroom time! Most folks have no clue as to the meaning of octane or what it is for that matter so let me give you the basics. When crude is refined, the results are hydrocarbons of different lengths. Some of these you would recognize like methane has one hydrocarbon atom, propane has three hydrocarbon atoms chained together, butane has 4, pentane has 5, hexane has 6, Heptane has 7 hydrocarbon atoms chained together and Octane has eight. These fuels are blended together to get other fuels. Heptane and Octane are mixed together to get todays gas. Heptane is unstable when compressed and this property is used to assist in the ignition of the gas. An 87 octane gas has 87% octane and 13% Heptane. It will ignite quicker and at lower combustion pressures than a 93 octane gas that has less Heptane. Octane will have marginally more BTUs therefore there is a little more energy to be had from higher octane but only if your engine is designed to take advantage of the higher octane. The Triton series of engines seems to like octane ratings around 89. Using a higher octane gas will slow the ignition of the flame front in the combustion chamber resulting in lower fuel mileage. It would be like running the engine with retarded timing.
Class over.

 

o know i guess flash is some sort of radical genuis!
we are not worthy!! for us stupid folks if it says use 87 then use 87!!!!!!!!!

CLASS OVER!!!!!!!

 

Flash, I have driven vehicles that have had a noticable increase in fuel milage when higher octane gas was used. If I understand what you're saying, the increase in milage was due to that particular engine "liking" the higher octane. My '97 F-150 showed a very marginal increase in milage when I used 93 (vs. 87)octane. So, maybe 89 will show the same result at less cost.

 

Joe, the fleets that we track, none of the Triton engines are getting better gas mileage with premium gas. Using 89 or 87 octane is a mixed bag. My personal truck is a 02 SCrew with the 4.6. It runs better and stronger with the 89 but there are no fuel mileage advantages. That is not always the case. Some of the Tritons seem to like and perform well with the 89 proof and give better fuel mileage. I would suggest running several tanks of each back to back, and track the mileage.

As much as Ford attempts to build the Tritons alike, there are differences. If you particualr engine comes out loose, it will perform differently than one that comes out tight. Same goes for the electronics. The electronics have ranges to be in spec. If most of your electronics are on the high end, it will perform differently than a truck whose electronics are at the low end.

 

Thanks flash. Your insight was infomative and easy to understand. I have had over 15 years as a factory Mercedes Benz and Porsche tech. Benz has done extensive studies and found that the higher octane fuel worked better in their cars. However, it was noticed over a length of time. The increase in milage was noticed when inconsistant fuel batches and regional differences in fuel could sort-of average out. The overall increase in fuel milage amounted to about 14%. plus less wear upon teardown. Porsche observed the same. Our trucks will probably find a similar benefit over time. I use 93 octane in my 4.6 and have had no problems. An increase of 14% is well worth the added cost of the higher grade fuel. The manufacturers recomend the lower grade stuff to keep cost of ownership down on the sticker price. Use the good stuff.

 

I have a 97 4.6L Scab 2WD with 80k miles. I always use 5W30 oil and regular gas (Costco or AM-PM mostly). I have never observed knocking and seem to get 16 mpg in the city and 18 mpg on the highway averaging 70mpg. Pulling my 17.5 ft Tracker Bassboat reduces the mpg by 2 mpg. I hope my 2004 FX4 Scab (on order) can do the same.

 

Ain't no such thing as a 4.6 getting 14% better mileage using premium fuel on a stock tune if there is nothing wrong with the vehicle.

If there's something wrong that's causing ping (which will make the engine pull back timing) then it could happen --- but Ford truck PCM's do not take advantage of premium fuel. The knock sensor pulls back timing from an 87 octane base timing, not from a premium fuel base timing.

If your performance is better on a stock PCM with premium, or you need use higher than 87 to prevent ping then either there is something wrong with the vehicle or the quality of gas you're buying is marginal.

To anyone who says "my truck needed premium from day 1 to prevent pinging" --- that doesn't mean there isn't something wrong. For example, many Rangers and Explorers came brand new with EGR issues that caused ping.

If you're not tuned for premium, you're throwing your money away.