Ford EEC computers

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EEC stands for Electronic Engine Control. Ford uses the computer to electronically control vehicle functions. Fuel injection computers are part of a broader title called Programmable Fuel Management Systems, whose main function is to supply a mixture of fuel and air to the engine that can be easily ignited by spark to produce reliable efficient power. The EEC computer contains chips for memory, micro-relays to control actuators, a processor, and a program to keep it all working smoothly. It looks to sensors to learn what environment the engine is operating in. It also looks at driver inputs to learn what you want to do. It processes the information it receives and calculates what the best fuel mixture and timing setting should be. It then activates those actuators to implement the previously calculated fuel mixture and timing. It cycles back to listen to the sensors again to insure the outcome was what the driver and computer wanted. All that happens in a millisecond and repeats at speeds so fast it can adjust calculations between firing cylinders at 6000+RPM. When it's all working in harmony it will last for over 30 years with only basic maintenance.

Ford started putting EEC in vehicles starting in 1978. There have been 8 versions of EEC.

EEC-I 1978 Ignition timing, EGR, and Smog pump.
EEC-II 1979 Carb (O2 feedback and fuel stepper motor), Ignition timing, EGR, and Smog pump.
EEC-III 1980 Central Fuel Injection (no Self-Test functions).
EEC-IV 1984 OBD-I (covered in text below).
EEC-V 1994 OBD-II (covered in text below).
EEC-VI 2003 Multiple connectors, No J3 connector for chips, complete Flash Memory capable.

Due to business reasons Ford had many cross overs. There were carburetors in 1988, and many other crossovers that make pinpointing individual applications almost impossible. Some times a vehicle manufactured for one state was delivered to another, and dealers traded cars frequently. So dates are relative most of the time.


EEC-IV has been Ford's computer of choice with enthusiasts for years. Its advanced programming can run almost any engine, while not being over complex. All the necessary engine controls are just as advanced as the newest vehicles coming out. While emissions controls and other secondary devises are easily deleted. EEC-IV uses the same 60-pin connector as III, but one of the indexing tabs on the outside is offset.

Ford EEC4 pinout.png

EEC internals

Intel and Ford had a joint venture building EEC. EEC uses a custom Intel 8061 chip for its processing functions. This chip is modified only for EEC and is soldiered into the computer board. This 8061 processor chip holds the factory fuel injection program and commands the rest of the internal components. There is also a custom Intel 8361 memory chip. The EEC has three different kinds of memory, ROM KAM & RAM. Read Only Memory or ROM is the long-term memory where the master program is kept. The ROM cannot be altered and lasts 20 years after the EEC is disconnected from voltage. Keep-Alive Memory or KAM is the complex mid term memory, this memory lasts for as long as EEC is receiving 12 volts. The KAM is where the trouble codes are stored, and where the sensor baselines are memorized. Random Access Memory or RAM is the short-term memory; this is where data is stored during a trip. Once the key is turn off the RAM is deleted.

The Intel 8061 processor chip holds the factory fuel injection program and commands the entire system. Within the program are Scalars, Functions, Tables, and Flow Charts. A Scalar is "a single numerical value assigned a label." It sounds more complex than it really is. A common easy to understand example is the engine limiter: "REVLIM = 6000." Functions are graphs, but Ford like to call them functions. It's usually an input vs an output. So more input causes more output and vise versa. Tables are more complex than functions and are 3 dimensional graphs, when 2 inputs influence an output. The flow charts combine the basic scalars, functions and tables to dictate within the program to calculate an output. Flow charts are more for human understanding than computer function; it helps us to look at a complete thought.

Scalar: REVLIM =6000 Function: Ford EEC function.png
Table: Ford EEC table.png Flow chart: Ford EEC flow chart.png

The programmed values within the EEC are different for each vehicle / year / engine / transmission model. Flow-Charts are not changeable, they are forever burned into the processor. These numbers within the scalars, functions, and tables can not be replaced. But they can be substituted with numbers by a chip. The EEC only has one or two Flow Charts that are a lot larger than the simple example above. The engine Flow-Chart is all combined and creates the system strategies, a second flow chart can be added for vehicles with automatic transmissions. It runs these flow charts at incredible speeds, a sequential fuel injected V-8 engine needs the injectors, and spark plugs activated 4000 times a second at 6000RPM. EEC-IV operates at 15MHz, that's the ability to do 15,000,000 tasks in one second. But there is more to do than send out a spark signal, reading a sensor takes one task away, EEC-IV has to check sensors in-between firing cylinders. Therefore the EEC has the capability to do 1000 functions in-between injector and spark plug firing.

There are main strategies that EEC uses to run the engine and back up strategies for emissions and diagnostics. In each strategy the master Look-Up table must use the sensors PIP, TPS, ECT, MAF or MAP. Those sensors run the show and which part of the flow chart EEC is directed down. The set values that dictate which Strategy to use and when to use them are different for each vehicle application. This table quickly explains the strategies control of fuel, timing, and emissions, for further information see the strategies page.

Strategy Fuel control Spark control Emissions Sensors in use
Start / Crank Open loop, preset enriched values TFI controlled None RPM / ECT
Cold Start & Warm Up Open loop, preset enriched values ECT Multiplier Air to CAT RPM / ECT / ACT
Cold Drive-Away ECT < 185 = Enrich, ECT > 170 = Lean RPM vs Load Multiplier, ECT Multiplier Air to CAT RPM / MAF or MAP / ECT / ACT / TPS
Warm Idle Preset Enriched Values Retard after 1 minute Intermittent Air to CAT RPM / TPS / ECT / ACT / HEGO
Warm Cruise Closed loop: 14.7:1 RPM vs Load Multiplier ECT Multiplier EGR Multiplier EGR Canister Purge Air to CAT RPM / MAF or MAP / TPS / ECT / ACT / EGR / HEGO
Part Throttle Acceleration Closed loop: 14.7:1 RPM vs Load Multiplier ECT Multiplier Air to CAT RPM / MAF or MAP / TPS / ECT / ACT / EGR / HEGO
Full Throttle Acceleration Open loop, preset maximum enrichment RPM vs Load Multiplier ECT Multiplier None RPM / MAF or MAP / ECT / ACT / TPS / KS / VSS
Deceleration RPM > 1500 = O, RPM < 1500 = 15:1 Preset Advanced Value Canister Purge RPM / ECT / TPS / VSS


EEC-V and EEC-IV are alike in a lot of ways. EEC-V is faster, has more capabilities, and has an easier to alter flash programming. EEC-V has a lot of the same programming it's just harder to read it. EEC-V is 18MHz that's 18,000,000 tasks in a second. For aftermarket needs that is sufficient for everyone's applications. Its internal memory is four times greater than EEC-IV. Today's cars with traction control, air bags, and cruise need these extra capacities. The EEC-V uses a new 104-Pin connector to accommodate more sensors and actuators to help it grow beyond just engine and transmission control.

Ford EEC5 pinout.png

The new EEC also had to apply to newer 1996 government regulations, these were labeled as "On-Board-Diagnostics II", and they required a new test plug called the Diagnostic Link Connector. All brands sold in the USA had to use the same test connector, and it has to be within reach of the driver's seat.

ODB2 connector

This connector makes inserting a chip into the EEC obsolete. Ford uses this connector to update the vehicle's program. They plug into the EEC and upload the most current program for emissions, transmission shifting, and other changes that Ford develops after you purchase the vehicle. Technology is being developed to the point where you can add an aftermarket performance programs just as Ford upgrades the stock program. One day we will be able to order an EEC-V from aftermarket with our specifications, engine size, sensors options, and transmission options. You pick the fuel ratios, you pick the timing curve, then wait for the mail, make your wiring harness to the included directions, hook it up and drive. No more searching for the best EEC, no more using just enough sensors to make it happy, and no more using dummy sensors to trick the EEC. As of now aftermarket is able to change the Look-Up-Tables from the Diagnostic Link Connector, and is currently hacking into the programming. The more they learn the more you can alter. Right now EEC-IV is the best Ford EEC to choose for swaps, EEC-V is only a good swap if you're going to use all its vehicle control functions. EEC-VI is starting to hit the streets. EEC-VI will not only replace EEC-V, but make EEC-V more appealing to aftermarket venders.

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