AEM_EFI_Basics_V1.3.pdf

Warning!

Use this system with EXTREME Caution! The AEM EFI System

allows for extreme flexibility in engine tuning.

Misuse of this product can destroy your engine!

Read this User’s Manual thoroughly before using this product.

Technical Help

NEED ASSISTANCE?

If you need technical or installation assistance with your AEM EMS System,

DO NOT RETURN THIS SYSTEM TO YOUR VENDOR.

Please contact our technical help department. Our technicians will be able

to solve most problems over the telephone.

Only AEM can authorize the return of this system after having

discussed your problem over the phone.

Call 800-423-0046 for technical assistance.

AEM is continuously adding features or making improvements to the AEM

EFI system. For the latest updates check www.aempower.com .

NOTE: AEM holds no responsibility for any engine damage that results from the misuse of this product!

This product is legal in California for racing vehicles only and should NEVER be used on public highways.

AEM EFI Basics

Version 1.3

Congratulations! You have just purchased the AEM Programmable Engine Management System (AEM

PEMS), the finest programmable engine management system on the market. The following information

details the features and operations of the AEM PEMS, as well as the engine requirements necessary to

successfully operate the AEM PEMS. To ensure proper use of this system and to prevent risk of damage

to your vehicle, you must read these instructions and understand them thoroughly before attempting to

program this unit.

The AEM PEMS

The AEM Programmable Engine Management System (AEM PEMS) is a Windows™-based, user-

programmable Electronic Control Unit (ECU) that uses a powerful 16/32 Motorola bit3 microprocessor

and has 1Mb memory for data storage. On most applications, the AEM PEMS is a “plug and play” (PNP)

installation, eliminating the need for time-consuming, expensive custom wiring harnesses. Additionally,

the AEM PEMS uses the vehicle manufacturer’s Original Equipment (OE) sensors, eliminating the need

to adapt sensors from another vehicle.

Functions and Controls

The AEM PEMS controls the fuel delivery, ignition timing, transmission shift points, and all ancillary

engine controls. The ancillary controls can be boost controllers, VTEC solenoids, staged inlet manifolds,

Nitrous Oxide systems, two-step rev limiters, and/or any other type of additional system that requires a

logic control. The AEM PEMS has 1 Mb of internal memory for data acquisition that records all input and

output channels at high speed for comprehensive data analysis and tuning ease. This data is displayed

in our AEMLog software in both easy-to-use text and graphical format. This is essential to the proper

tuning of the engine. Data acquision stores important engine data to help determine the running

condition of the engine. This data allows the tuner to make changes to the engine calibration for

maximum power and reliability. Just a few of the items displayed are air fuel ratio (AFR), Ignition

timing, knock information or any parameter that relates to the operation of the vehicle. Even non-

engine parameters can be displayed such as vehicle speed through wheel speed sensors, drive

shaft speed, or accelerometer information. The data acquisition system also displays oscilloscope

patterns for input signals for various magnetic, Hall effect or infrared sensors on the vehicle. This feature

aids in the diagnosis of potential noise or synchronization problems.

In addition to comprehensive data acquisition, the system is capable of aiding in engine diagnosis by

allowing the tuner to perform cylinder balance testing by shutting off one injector or spark plug at a time

and recording the RPM change between cylinders.

AEM PEMS Operating System

The AEM PEMS is Windows™-based and therefore uses this familiar format for copying, moving,

viewing, and manipulating data. User-defined templates are configurable and enable the tuner to

establish a “quick key” to organized, useful information during the tuning process. Up to 12 template

buttons can be made to cover virtually any tuning parameter at the click of a button.

The major advantage of Windows™-based software is that the user can utilize a mouse for quick data

entry; as opposed to the slow, cumbersome key entry method of a DOS based system. The software is

infinitely adjustable so that virtually any combination of engine control, power adder(s), and ancillary

device(s) can be programmed to maximize the potential of the vehicle. Furthermore, the AEM PEMS is

capable of accurately delivering the proper amount of fuel and correct ignition timing for any boost level

or possible operating condition.

Required Tools for Operation

A PC (preferably a notebook computer) equipped with Windows 95, 98, 2000, NT, or Me edition-operating

program with at least a Pentium 100 processor and 16 Mb memory is required to run the AEM PEMS

software. The computer connects to the AEM ECU via a standard serial cable that can be purchased

through AEM or a local computer supply store. There are no special connectors or cables to buy. If

1/25/02

AEM EFI Basics V1.3.doc

you purchased the AEM Racing PEMS, a wire harness kit and sensor terminations will have to be

purchased from AEM. If any sensors other than OE sensors are used it will be necessary to purchase the

appropriate sensor terminations through AEM. These sensors can also be purchased from an electronic

fuel injection (EFI) system component supplier.

The user of the AEM PEMS MUST have an excellent understanding of internal combustion engine in both

theory and operation. This includes not only the mechanical aspect of the engine, but it’s requirements in

terms of air/fuel ratio, ignition requirements, and mechanical limits. AEM provides conservative guidelines

for base ignition timing and recommended air/fuel ratios. We recommend that the ignition timing be set 5 °

retarded from stock on a naturally aspirated engine and 10 ° retarded on turbo or nitrous oxide engines. It

is very beneficial to have a fast response air/fuel measurement system to get the best performance from

your engine. If a wide-band oxygen sensing system or UEGO system is not used, we recommend

starting even richer than the guidelines suggest.

Installation Requirements

The AEM PEMS will ONLY perform correctly on an engine that is in proper working order. It cannot

compensate for engine problems such as an improperly timed camshaft, poor compression or any other

mechanical problem. Please ensure that the engine is in good working order before installing this ECU.

The AEM PEMS must be located in a water-safe part of the car. It is important to place it where it will not

encounter temperatures in excess of 160 ° C. The preferred mounting location is in the interior of the car.

In the case where a PNP unit is used, the stock location is ideal. NEVER run the ignition wires, or any

high power wire in close proximity to the ECU as this may cause RFI or EMI problems. Only ignition

wires with a carbon core or “spiral wound” core should be used. Do NOT use metallic conductor wires.

ANY DEVIATION FROM THIS WILL RESULT IN IMPROPER OPERATION OF THE AEM PEMS.

Fuel Delivery System Requirements

Adequate fuel delivery is generally the greatest problem that we have encountered when tuning and

calibrating EFI systems. We cannot stress enough how important it is to have adequate, consistent fuel

pressure, and volume to the injectors. The use of a properly sized fuel line from the tank, fuel rail and

return hose is imperative. Measures must be taken to eliminate excessive pulsations in the fuel rail so

the injectors get even fuel flow. These instructions will review the entire fuel delivery system in the

following section to help you design your own comprehensive fuel delivery system. On vehicles using the

PNP version of the AEM PEMS, all of the essential elements for adequate fuel delivery are designed into

the stock fuel system. If you are using a PNP system on a vehicle that is heavily modified (forced

induction, nitrous oxide, etc.) pay close attention to the following information regarding fuel delivery, as

the OE fuel delivery system may not be capable of supplying an adequate amount of fuel.

Fuel Tank or Fuel Cell

In most cases the stock fuel tank is acceptable for street use. Most OE fuel tanks have internal baffles to

reduce fuel slosh in the tank, which reduce the chances of intermittent fuel delivery.

Fuel cells are the best means of fuel storage because they eliminate the chance of fuel slosh by using a

foam liner that dampens the fuel travel. Fuel cells also have the fuel pick up placed in a position that is at

the lowest portion of the tank—or in the case of a drag racing car—in the rear of the tank where the fuel

shifts to during acceleration.

In either case, the tank must be vented to provide air for displaced fuel as the engine consumes it. The

tank must also have provisions for fuel return. It is important that the fuel return be placed as far away

from the pick up as possible to prevent foaming or bubbles at the inlet.

1/25/02

AEM EFI Basics V1.3.doc

Fuel Pump Sizing

To achieve proper fuel delivery, you must select the right fuel pump for your vehicle. In most cases, where

the engine has been modified only with “bolt on” performance items, there is rarely need for a larger fuel

pump or larger injectors. Vehicle manufacturers typically design a “safety factor” into the fuel pump to

accommodate the deterioration of the fuel system over time. This safety factor is intended to compensate

for a fuel filter that is nearing the end its life, or for deposits in the injector orifice. Our research has

revealed that generally there is about a 15%-20% oversize in most factory fuel pumps.

If the engine is enhanced via forced induction or nitrous oxide, the stock fuel pump is inadequate. If the

engine’s power is increased more than 15-20% fuel delivery must increase as a factor of the power

gain.

The way to determine the proper-size fuel pump is based on the desired brake specific fuel consumption

(BSFC) of the engine. This term refers to how much fuel in pounds per hour (pph) the engine consumes

per horsepower and is a measure of the efficiency of the engine. It is a useful term in determining the

total fuel requirement of the engine.

On vehicles equipped with forced induction or nitrous oxide, higher BSFC’s are required as an added

measure of safety to prevent detonation or high combustion chamber temperatures. Below is a guide of

BSFC’s with standard CR that AEM uses for various engines that run on gasoline:

• Naturally Aspirated engines have a BSFC of .48 to .50

• Forced Induction engines have a BSFC of .65 to .68

Methanol (alcohol) powered engines require twice the amount of fuel so the BSFC’s are doubled.

Calculating the total fuel requirement of an engine requires simple equations that we outline in the

following section. You must know how much power the engine is anticipated to make and we

recommend that you guess on the high end. The fuel requirement will be determined in pounds per hour

of fuel flow. Since most pumps are rated in gallons/hour you must know the weight of your fuel/gallon.

(The vast majority of gasoline based fuels run at 7.25 lbs./gallon.)

The equations to determine your fuel requirement is as follows:

• (Power x BSFC) x (1 + Safety Margin) = pounds/hour

• Pounds/hour / 7.25 = gallons/hour.

An example of this equation is:

• 500 hp gasoline engine using moderate boost with a 30% safety margin

• (500 x .625) x 1.30 = 406.25 lbs./hr.

• 406lbs/7.25 = 56 gallons/hour.

• If the pump that is being considered is rated in liters per hour, use the conversion factor of

3.785l/gallon. The pump described above would be rated at 56 gallons x 3.785 liters = 211.96

liters/hour.

In the fuel pump sizing, always use a safety margin greater than 20%.

Fuel Pump Location

The fuel pump should be located at a level that corresponds the lowest part of the fuel tank. This does

NOT mean that the pump should be in a vulnerable position such as hanging below the tank. The pump

should also be positioned so that it is protected from the road hazards (speed bumps, curbs, road debris

etc.). In the event of an accident, the vehicle structure around the fuel pump should not deform to a point

where the pump and its electrical connections are compromised.

1/25/02

AEM EFI Basics V1.3.doc

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: