I know the manual states to use 87 octane only. I was wondering how would it damage the motor, if using 93 oct. could damage the motor. What creates carbon deposits in the motor? Does the 93 octane burn hotter to help prevent that, or make it worse? Just wondering.

 

Unless you've modified your engine and it now has a higher compresion ratio it would be a waste of money to use a higher octane fuel. The way I understand the octane rating is the higher the number the more resistant it is to pre-ignition or detonation. You won't see any performance gain and you'll probably see a reduction in fuel economy. Probably the best way to reduce carbon deposits is to "get on it" once in a while to blow out the excess carbon.

 

Please search on this topic. It has been covered, but if you want to waste your money on something that won't help you..... go ahead.

For the most part Bruker is correct.

If you want to reduce carbon, got get yourself a can of SeaFoam and have at it.

 

yeah, unless you fork out 200 bucks for a diablo chip (like i did) premium isnt worth it, but when you have the chip....

 

If you are curious try it. Keep good records of your mileage and see what happens. I did and gained about a mile per gallon and the pinging went away in my 1999 3.0 Ranger. Has a bit more power too.

Only way to know for sure is to try it. Also, motor oil can make a difference. Try Valvoline Durablend, you might be surprised. I switched from Valvoline dino to durablend and was amazed at the difference.

 

the only reason for higher octane is the prevent detonation and pinging otherwise it has no purpuse so if your truck is pinging then its good but if not its a waste of money i know this im going to school for auto tech and thats what i have learned so if u have any othere questoins email me at smoky19781998@comcast.net
the spaces are so you can see it otherwise its all together

 

I run 89 octane in my ranger, only to keep it from pinging when under heavy load. Otherwise, used to just run 87.

 

Our Rangers engine isn't designed nor timed to make good use of premium fuel.

Using premium is sort of like retarding the timing, as premium fuel is a little harder to ignite, so at our compresion ratio, so it has a slower flame front.

As such all of it isn't completely consumed on the power stroke.

The unburned excess fuel & additives, end up as deposits on the piston crowns, combustion chamber, plugs & exhaust valves & the cat converter has to process any that reaches it to, so premium in these engines has no good purpose & as has been said.

It is a useless waste of money on a stock engine IMHO.

 

I wonder if in the case of the 3.0 FFV that maybe the PCM is able to adjust the timing and fuel control for optimum use of the higher octane gasoline ?

E85 has an octane rating of 105-110, PCM can adjust the timing and fuel control to work with this high octane.

If so this could explain why my 3.0 FFV gets better gas mileage and more power with the higher octane gasoline. I dont use it for better mileage but rather to stop the pinging. The increase gas mileage and power is just icing on the cake.

Here is some further information on E85 and on how the PCM in the FFV vehicles work

http://www.renewableenergypartners.org/ethanol.html

http://www.asashop.org/autoinc/dec2004/techtips.cfm

I found this to be particularly interesting "vehicles can be ethanol-optimized (capable of running only on ethanol) to achieve superior gas mileage as compared with gasoline."

 

why would the truck still knock when i switched to premiem gas
i have a 1999 ford ranger xlt 4.0 6 cly
i replaced the wires , plugs , maff sensor

 

Premium grade fuel resists burn more than regular grade fuel. It is initially designed for higher compression engines, but if you were to run Shell or Petro-Canada premium, they have additives that help clean fuel injection systems and carbon deposits as you drive.

To drive this fact home, I did a rebuild on a 360FE in my 69 Ford. The heads were caked with years worth of carbon buildup. I dunked them, and had them spotlessly polished up with a drill and scotchbright pad. About 45,000 miles(not k) after the rebuild, a wrist pin keeper let go, and I was busy looking for another block to rebuild.

I lucked out on a parts truck, and ended up with a 390. Since my heads were already re-done, and ported, I re-used them. Upon removal(and only running on Petro-Can premium) the heads were covered in a mild grey dust that would wipe off to shiny metal with your finger.

For those of you with lower compression engines. You can bump your timing advance up a couple of degrees or so if running premium only, and gain a bit of power and mileage there.

For those in colder winter climes, running premium in the winter time can have adverse affects on cold starts. I run premium when going on a long highway trip in the current 81 F150 400M block, but run regular the rest of the time, for short trips.

One side note on premium fuel. Because it resists burn, during extremely hot weather your engine will run cooler than it will on regular.

Detonation is mostly caused by carbon deposit buildup getting so hot that it glows, and it ignites unburnt fuel left in the combustion chamber even when a given cylinder is not on compression/fire stroke.

 

GWIGG: Common situation with Rangers is carbon build up both in the combustion chamber and the passage behind the EGR valve through the intake manifold. The carbon in the EGR chamber reduces the flow of exhaust gasses into the combustion chamber causing the ignition to be hotter than normal. Yes the exhaust gasses actually cool the combustion for emission purposes. The carbon build up in the combustion chamber will raise the compression ratio. Changing gasoline will not fix the problem - decarbonizing will have a big impact.

See the thread in the Read Me First Technical Section titled how to decarbonize a 4.0. Which ever engine you have the theory behind this procedure will transfer just fine.


Good Luck

Russ

 

I have ran 93 many times in my Ranger, usually for road trips, but also for everyday driving too. With the 93 I have better acceleration and my gas milage increased by 2-3 mpg. Since I have kept extensive records of milage I have the data to show that the use of 93 octane has increased gas milage in my Ranger--it depends on whether you want to spend the extra couple of bucks at the pump! ...just my $0.02