madeSICC

With shift points etc.. the lower you go the more "economical" your truck will be when you go in the higher numbers the more performance oriented it will be.

ak_cowboy

I've got my shift firmness at +7 all around and set my 3-4 shift a little lower, so that it kicks into o/d sooner when i'm cruising around town.
I've been getting 15mpg w/o too much trouble, and know I can get 16 if I tried. A lot has to do with driving style.

JCP281

See this is another thing I find laughable(not knocking on you personally FSU FX4, speaking more from a marketing standpoint). There is virtually no power to be had with a tune on 87 octane. The only thing that can be done for any performance feel is lean the stock pig rich fuel trims out and firm up shift points. The only timing that can be added is very minimal with 87.

Skull31

Ya i have no idea on what you just said,lol.
"The only thing that can be done for any performance feel is lean the stock pig rich fuel trims out and firm up shift points. The only timing that can be added is very minimal with 87" Can you explain what all that means?This is what i am talking about for those of us who dont know much about this kinda stuffBut who wants to learn about it

JCP281

First off: If you REALLY want to grasp the concept of tuning, buy and read that book I posted. It is an excellent way to spend 20 bucks.

As the truck comes from the factory, the tunes that come with them are VERY safe. There is a ratio called the air/fuel ratio that is based off a concept in chemistry called stoichiometry. When you are just cruising around driving normal the ratio will read 14.7. This is a perfect ratio for a gas motor. However, when you go full throttle, more fuel is added and the ratio changes.

Basically the higher the stoichiometric number, the leaner(hass more air and less fuel) the motor will run. The factory makes the tune so that at full throttle the A/F ratio is rich, meaning a lot of fuel added. Iv seen readings as low as 10.5 for a stock tune. That is PIG rich.

tuning your car in the fuel trims to get your wide open throttle A/F ratio around 12.5-13 is optimal for a naturally aspired motor. It provides some of the best, safe fuel trims for performance; it also saves some gas.

You get these numbers from measuring your exhaust gas with a wideband A/F meter. DO NOT GET THIS CONFUSED WITH THOSE POS NARROW BAND GAUGES RICERS USE TO LOOK COOL! THOSE DO NOTHING.

So to recap Ch.1:
your A/F ratio is a stoichiometric relationship where the higher the number the leaner the motor, and vise versa.

14.7= cruising A/F ratio, always unless your front o2 sensors are bad*

Now, to address the timing:

87, 89, 91, 93 octane gases are not just distinguished by the different added detergents. The fundamental difference between them is whats called their heating value. the higher the octane, the higher the heating value for that gas. This higher heating value means that the gas takes longer to completely burn. Consequently, it also has more internal energy to yield from the combustion.

when you increase the timing, you fire a spark sooner. This is good for 93 octane because it has longer to burn before its fully compressed in the engine. When you increase the timing to much on an 87 octane fuel, the fuel is burnt to fast and a condition called detonation occurs. FYI, detonation, just like it sounds, is not good.

87 octane does not posses enough internal energy to utilize more than 2-3* of advanced timing without starting to detonate. So the fact that a company calls an 87 octane tune "performance" is basically a lie. LOL

Ch 2 Summary:

Octane rating tells you in a nutshell how much timing can be added.

To much timing= boom

----------------------------------------
* Natural fluctuations occur from about 14.3-15, the average is about 14.7

BassAckwards

Are you sure that 93 octane rated gas takes longer to burn?? Because my uncle is a petroleum engineer and he said that part of the advantage of higher octane rating is that the fuel burns more instantaneous and quicker and burning quicker also means that it won't heat up your engine as fast because its not detonating in as long of a time frame.

But to help contribute to the thread and give some settings to people new to the tuner, here is what I've been running and I would love for anyone who knows more about tuning than I to improve upon it. And this adds a great deal of difference with my taller tires!

Performance Tune (Level 3) 93 Octane Only
WOT Shift: 1st-2nd 5300; 2nd-3rd 5300; 3rd-4th 5000
WOT Fuel: 1.8
Timeing: 1.5
Shift Firmness: 12-all
Rev Limiter: 5450
Standard Lock Points: 3rd -4; 4th -6
Tires: <Insert your tire Circumference here>
Gear Ratio: <Insert your gear ratio here>

JCP281

Im affraid your uncle needs to reference his chemistry book.

Higher octane requires more time to burn to release all its energy. It burns slightly slower.

EDIT: Ill elaborate:

Higher octane has more chemical bonds, so it takes longer for those bonds to break.

BassAckwards

I do recall him saying there were more bonds, but he said something about these bonds breaking apart in a more even manner and not sporadic like lower octane fuels.

But no matter I don't feel its worth discussing to in-depth, lets just help people figure out how to tune their truck! I know I would love some advice

JCP281

That may be the case about uniformity, but it still takes more time for the bonds to split and completely burn.

LOL I went and looked it up before I even responded just to make sure I was on the ball with my original post. That book had quite a bit of dust on it, thats for sure!

BassAckwards

I must simply be misquoting him/misunderstood him lol

But idk if you know a whole lot about tuning, but what do you think of my settings, if you know anything about them.