Few questions
10-13-2006, 01:46 AM
#1
3rd Gear Member
Thread Starter
Join Date: Oct 2006
Location:
Posts: 905
Few questions
Hiya, i dun own a 5.0 ( wish i did) they have been in my family tohugh since i was a little kid, uncle had a pace car 5.0, cousin has had 3 5.0s my bro has a 5.0 with a 306 waiting to be installed... so yea just some things i wanted to know since i love expanding my automotive knowledge
What is Running "Rich" mean?
How does a tune affect wether you ahve to us 87 or 93 octane? is it the compression ratio?
Whats the difference between Speed density and MAF?
i have a few more questions but i can't think of them atm just that i am always reading these boards and some things idk what you guys are talking about lol
What is Running "Rich" mean?
How does a tune affect wether you ahve to us 87 or 93 octane? is it the compression ratio?
Whats the difference between Speed density and MAF?
i have a few more questions but i can't think of them atm just that i am always reading these boards and some things idk what you guys are talking about lol
10-13-2006, 01:51 AM
#2
6th Gear Member
Join Date: Sep 2005
Location: Hamilton, NJ
Posts: 15,042
RE: Few questions
This might be hard for you to understand at first but you will get it eventually. It explains alot about what you are asking about, mass air, SD cars, etc. Also, if you want a better understanding this article was in last months Muscle Mustangs and Fast Fords. There are pictures in the article also that help a little bit. Good Luck. Anymore questions, let us know! 
10-13-2006, 01:54 AM
#3
6th Gear Member
Join Date: Sep 2005
Location: Hamilton, NJ
Posts: 15,042
RE: Few questions
Inside The Black Box (Part 1)
Understanding and Tuning Your Ford EFI System
Some of us have been there. Others never have. For those who have seen the inside, we realize it’s a scary and confusing place. We slowly found our way around the “safer areas.” than ventured further as we felt more comfortable. Still, years later, there are unknown caverns where we fear to tread. The place we speak of does not exist in the physical world - it’s a virtual one. We’re talking about the world of the Ford Electronic Engine Control system.
Not too many years ago, the means to get inside and reprogram the Ford Electronic Engine Control (or EEC, pronounced eek ) system was reserved to few who possessed the specialized systems and electronic engineering knowledge to read and “reverse engineer” the Ford EEC system. But in this day and age, in addition to several stand-alone electronic engine control systems (that totally replaces the stock system), there are many aftermarket systems available with the ability to reprogram your existing Ford EFI system, either through an add-on chip or by reflashing to stock processor.
In this three-part series, we’ll give you the background info on how the EEC systems work. In part 2 we will discuss simple tuning specifics (as far as the Ford EEC system parameters go), while in Part 3 we’ll go through some actual tuning techniques (again, very much simplified). In the end, you’ll hopefully understand what your hired tuning expert is doing.
THE SIMPLE EXPLANATION
The Electronic Control Unit (ECU, aka Powertrain Control Unit or PCM) is the brain of the entire EEC outfit. It uses various sensors to “see” current running conditions and understand driver demands, then makes decisions and perform calculations based on its internal programming (on board memory). Finally, it sends electronic outputs to a host of actuators which control the fuel and spark delivery for the engine, emissions control systems, coolant fans, automatic transmission functions, and so on. As EEC systems have evolved and continue to do so, the ECU gains control over more and more variables. In this series, we will focus primarily on the fuel and spark control, since they have the greatest influence on engine performance.
FUEL CONTROL BASICS
Before we go into detail on the three different fuel control strategies, you need to understand the fundamental similarities between all EFI systems. That leads us to the electronic fuel injectors and the EFI fuel system. It’s a simple enough concept. For a constant air/fuel (A/F) ratio, as the airflow into the engine increases (from increased rpm, increased throttle opening, or increased boost, for example), the fuel flow must also increase proportionately. But with electronic fuel injectors, the added fuel flow does not come from increasing the flow through the injectors the same way, as say, the throttle valve increased the airflow by opening the passage in the inlet path. Electronic fuel injectors are actually digital (on/off) devices.
An electronic fuel injector is an electrically controlled on/off valve for fuel flow. When it’s on, it flows fuel in proportion to its nozzle size, and fuel pressure. When it’s off, meaning they are opened and closed quite rapidly. If more fuel is needed, the “on” pulse gets longer. The amount of time the injectors are open is termed Pulse Width.
Or the time between successive pulses gets shorter. This is important, since many people don’t understand how you can flow more fuel with a shorter pulse width. The ratio between injector “on time” and on time plus “off time” (total cycle time) is know as the Duty Cycle, DC. For example, if the PW (on time) is 2.5 milliseconds (ms), and there are 5 ms between injections, the DC will be 0.5 or 50 percent.
Injection events can either be done in batch fire mods, where groups (banks) of injectors are fired at the same time (usually once per engine revolution), or in sequential mods, where individual port injectors fire for their cylinder only, normally following the engine firing order (once every second engine revolution for four stroke engines). Sequential EFI (SEFI) systems have some advantages for fuel control over batch systems (like improved emissions and rev limiting ability), and are therefore used on all modern OEM EFI systems.
For a given injector size, at a fixed fuel pressure, the fuel flow rate will increase directly proportionally to the duty cycle. That is, until you reach 100 percent DC. At that point, the injectors are theoretically open all the time, and fuel flow can’t increase unless the fuel pressure is increased - we’ll get to that in a minute. If you get to the point of saturating the injectors (100 percent DC), you’re a/F ratio will go lean if additional air flows into the engine. Hence the reason to install larger flow injectors. In practice, you typically don’t want to exceed 85 percent, since the injectors can overheat from all the applied current. Also at high DC the injector pulse width can become unstable, and with some injectors, less fuel will actually flow at high DC’s.
So maximum fuel flow will then be limited by the size of your injector, right? Not totally. The other variable is the fuel pressure acting across the injector (from the supply side to the intake manifold side). For a given nozzle size, you can push more flow through with a higher fuel pressure. This is why injectors are flow rated at a specific fuel pressure. It is also why you can get away with smaller injectors when using a Fuel Management Unit (FMU) that’s included in many supercharger kits. The FMU basically cranks the fuel pressure way up under boost to force more fuel through the smaller injectors. It’s really a Band-Aid solution to having properly sized injectors, because the high pressure can shorten the life of your injectors and your fuel pump.
So for a given injector size, we now have two variables to control our fuel flow: DC and Fuel Pressure (FP). To make life easier for the Ecu to control the fuel flow precisely, we’d like to have only one variable, so the FP is fixed at a constant value, typically 39 psi for most stock EFI fords. But if we want constant fuel pressure, why do we regulate it with manifold vacuum in order to maintain a constant pressure across the injector? As intake manifold vacuum increases, the intake pressure decreases, therefore we reduce the fuel rail pressure the same amount to maintain the constant pressure drop across the injector. For boosted applications, we need to do the same thing in the other direction, i.e., as boost increases manifold pressure, we need to similarly increase the fuel pressure (although most stock fuel pressure regulators will not do this). The confusing part is we normally talk about manifold vacuum in units of inches of Mercury (in. Hg), while boost and fuel pressure are usually measured in pounds per square inch (psi). If you do the units conversion, at 15 in. Hg manifold vacuum (idle with a mild cam), we should reduce fuel pressure by about 7psi.
On the earlier EEC cars, the fuel system was a return-style system, where the electric fuel pump in the tank simply pumped fuel at full flow all the time. The (manifold vacuum modulated) fuel pressure regulator then bypasses the excess fuel back into the tank. With the newer returnless fuel systems, it gets a bit more complicated. Now the ECU senses fuel pressure in the fuel rails and relative to the manifold vacuum, and controls the fuel pressure across the injector by pulsing the pump voltage. With this system, fuel is not needlessly pumped around and around, heating up in the process. But it requires a special pump to work with pulsed voltage.
Now that you understand the basics of fuel delivery, you need to understand how the Ecu decides the proper injector pulse width or
Understanding and Tuning Your Ford EFI System
Some of us have been there. Others never have. For those who have seen the inside, we realize it’s a scary and confusing place. We slowly found our way around the “safer areas.” than ventured further as we felt more comfortable. Still, years later, there are unknown caverns where we fear to tread. The place we speak of does not exist in the physical world - it’s a virtual one. We’re talking about the world of the Ford Electronic Engine Control system.
Not too many years ago, the means to get inside and reprogram the Ford Electronic Engine Control (or EEC, pronounced eek ) system was reserved to few who possessed the specialized systems and electronic engineering knowledge to read and “reverse engineer” the Ford EEC system. But in this day and age, in addition to several stand-alone electronic engine control systems (that totally replaces the stock system), there are many aftermarket systems available with the ability to reprogram your existing Ford EFI system, either through an add-on chip or by reflashing to stock processor.
In this three-part series, we’ll give you the background info on how the EEC systems work. In part 2 we will discuss simple tuning specifics (as far as the Ford EEC system parameters go), while in Part 3 we’ll go through some actual tuning techniques (again, very much simplified). In the end, you’ll hopefully understand what your hired tuning expert is doing.
THE SIMPLE EXPLANATION
The Electronic Control Unit (ECU, aka Powertrain Control Unit or PCM) is the brain of the entire EEC outfit. It uses various sensors to “see” current running conditions and understand driver demands, then makes decisions and perform calculations based on its internal programming (on board memory). Finally, it sends electronic outputs to a host of actuators which control the fuel and spark delivery for the engine, emissions control systems, coolant fans, automatic transmission functions, and so on. As EEC systems have evolved and continue to do so, the ECU gains control over more and more variables. In this series, we will focus primarily on the fuel and spark control, since they have the greatest influence on engine performance.
FUEL CONTROL BASICS
Before we go into detail on the three different fuel control strategies, you need to understand the fundamental similarities between all EFI systems. That leads us to the electronic fuel injectors and the EFI fuel system. It’s a simple enough concept. For a constant air/fuel (A/F) ratio, as the airflow into the engine increases (from increased rpm, increased throttle opening, or increased boost, for example), the fuel flow must also increase proportionately. But with electronic fuel injectors, the added fuel flow does not come from increasing the flow through the injectors the same way, as say, the throttle valve increased the airflow by opening the passage in the inlet path. Electronic fuel injectors are actually digital (on/off) devices.
An electronic fuel injector is an electrically controlled on/off valve for fuel flow. When it’s on, it flows fuel in proportion to its nozzle size, and fuel pressure. When it’s off, meaning they are opened and closed quite rapidly. If more fuel is needed, the “on” pulse gets longer. The amount of time the injectors are open is termed Pulse Width.
Or the time between successive pulses gets shorter. This is important, since many people don’t understand how you can flow more fuel with a shorter pulse width. The ratio between injector “on time” and on time plus “off time” (total cycle time) is know as the Duty Cycle, DC. For example, if the PW (on time) is 2.5 milliseconds (ms), and there are 5 ms between injections, the DC will be 0.5 or 50 percent.
Injection events can either be done in batch fire mods, where groups (banks) of injectors are fired at the same time (usually once per engine revolution), or in sequential mods, where individual port injectors fire for their cylinder only, normally following the engine firing order (once every second engine revolution for four stroke engines). Sequential EFI (SEFI) systems have some advantages for fuel control over batch systems (like improved emissions and rev limiting ability), and are therefore used on all modern OEM EFI systems.
For a given injector size, at a fixed fuel pressure, the fuel flow rate will increase directly proportionally to the duty cycle. That is, until you reach 100 percent DC. At that point, the injectors are theoretically open all the time, and fuel flow can’t increase unless the fuel pressure is increased - we’ll get to that in a minute. If you get to the point of saturating the injectors (100 percent DC), you’re a/F ratio will go lean if additional air flows into the engine. Hence the reason to install larger flow injectors. In practice, you typically don’t want to exceed 85 percent, since the injectors can overheat from all the applied current. Also at high DC the injector pulse width can become unstable, and with some injectors, less fuel will actually flow at high DC’s.
So maximum fuel flow will then be limited by the size of your injector, right? Not totally. The other variable is the fuel pressure acting across the injector (from the supply side to the intake manifold side). For a given nozzle size, you can push more flow through with a higher fuel pressure. This is why injectors are flow rated at a specific fuel pressure. It is also why you can get away with smaller injectors when using a Fuel Management Unit (FMU) that’s included in many supercharger kits. The FMU basically cranks the fuel pressure way up under boost to force more fuel through the smaller injectors. It’s really a Band-Aid solution to having properly sized injectors, because the high pressure can shorten the life of your injectors and your fuel pump.
So for a given injector size, we now have two variables to control our fuel flow: DC and Fuel Pressure (FP). To make life easier for the Ecu to control the fuel flow precisely, we’d like to have only one variable, so the FP is fixed at a constant value, typically 39 psi for most stock EFI fords. But if we want constant fuel pressure, why do we regulate it with manifold vacuum in order to maintain a constant pressure across the injector? As intake manifold vacuum increases, the intake pressure decreases, therefore we reduce the fuel rail pressure the same amount to maintain the constant pressure drop across the injector. For boosted applications, we need to do the same thing in the other direction, i.e., as boost increases manifold pressure, we need to similarly increase the fuel pressure (although most stock fuel pressure regulators will not do this). The confusing part is we normally talk about manifold vacuum in units of inches of Mercury (in. Hg), while boost and fuel pressure are usually measured in pounds per square inch (psi). If you do the units conversion, at 15 in. Hg manifold vacuum (idle with a mild cam), we should reduce fuel pressure by about 7psi.
On the earlier EEC cars, the fuel system was a return-style system, where the electric fuel pump in the tank simply pumped fuel at full flow all the time. The (manifold vacuum modulated) fuel pressure regulator then bypasses the excess fuel back into the tank. With the newer returnless fuel systems, it gets a bit more complicated. Now the ECU senses fuel pressure in the fuel rails and relative to the manifold vacuum, and controls the fuel pressure across the injector by pulsing the pump voltage. With this system, fuel is not needlessly pumped around and around, heating up in the process. But it requires a special pump to work with pulsed voltage.
Now that you understand the basics of fuel delivery, you need to understand how the Ecu decides the proper injector pulse width or
10-13-2006, 06:38 PM
#7
6th Gear Member
Join Date: Sep 2005
Location: Hamilton, NJ
Posts: 15,042
RE: Few questions
yea I did type it out.... it took like 5 hours! I dont think you understand how boring it is sitting on a computer form 9-5 doing nothing lol I will do ANYTING to pass the time lol I copied it out of the MM&FF magazine. I wanted it to be a sticky becuase its a really good article but I guess noone was really interested..... 
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