Electronic Engine Control

These will be the more difficult tech pages; but once read, and understood the rest will fall into place.  These pages are far from perfect or 100% accurate, but I will categorize Electronic Engine Control starting in 1978.  Electronic Engine Control is Fords “computer” for running engine systems; it is abbreviated to EEC but pronounced as “eek.”  There have been 3 major production versions of EEC:  III, IV, & V; EEC-III 1980 – 1985, EEC-IV from 1986 – 1993, and EEC-V from 1993 to current.  Unfortunately American capitalism drives Ford, “just because you making a new toy doesn’t mean you can’t sell the old toys until they’re gone.”  This is called crossover, there were carbs in 1987, EEC-IV in 1996, EEC-V in 1993, and many other crossovers that make pinpointing individual applications almost impossible.

EEC-III

EEC-III is an item we will acknowledge but not discuss in depth.  EEC-III was used with carbureted engines as well as diesel trucks.  It had a 60-pin connector but did not have all the pins inserted into the computer.  EEC-III controlled timing, some carburetor functions, and some emissions controls.  Publication and the aftermarket have not shown much light on this computer system.  Below is the 60-pin connector:

 

EEC-IV

EEC-IV has been a Ford workhorse for years; I’m not going to compare EEC-IV with other fuel injection systems.  EEC-IV is externally the same to EEC-III and uses same 60-pin connector but EEC-IV’s have all pins inserted in the computer whether they're used or not.

It isn’t the actual component that is so special, but the programming inside.  This is currently the best choice for engine swaps and upgrades.  The internals of EEC are complex; Intel and Ford had a joint venture building EEC.  EEC uses this Intel 8061 chip modified only for EEC it is soldiered into the board.  This is what controls the rest of the internal components and where the factory program is kept.  Within the program are Look-Up-Tables and Flow Charts.

 

The Look-Up-Tables are the values that Ford inserts into the program.  Examples are; engine 175F, air 15parts fuel 1part, HEGO 0.3V, injectors 25%.  Below is a very simple Look-Up-Table for MAP and ECT.

The values with in the EEC are different for each vehicle/ year / engine / transmission model.  Fuel values are written as injector duty cycles.  A Duty Cycle is an osculating waveform, making the injectors flutter are a certain rate.  Timing curves are different for each application as well; the timing values are seen as “additions to base.”  This means each condition met adds a set amount to the timing.  An example would be Wide-Open-Throttle adds 10 degrees to the current timing.  These values within the Look-Up-Table can be replaced with others, more on that later.  The program uses the values coming in from the sensors; plugs them into the Flow Charts; and it sends out a command.  Examples are; TPS at set value à go to certain strategies, engine idling for so long à go to certain emissions strategies.  Below is a simple Flow-Chart I made (HINT: read it slowly.)

Flow-Charts are not changeable, more on that later.  The EEC only has one or two Flow Charts that are a lot larger than my simple example.  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.  So if your doing the math, we still have the capability to do 1000 functions in-between injector open and spark plug fire.  We don’t really need to go any further into this, just understand it works.

 

There are basically eleven Strategies EEC-IV understands, this means there are 11 sets of Look-Up-Tables.  At the top of the master Look-Up table are a few sensors the PIP, MAF or MAP, ECT, and TPS (in that order).  These sensors run the show, they direct which branch of the flow chart EEC is directed down.  The set values that dictate when to use which Strategy are different for each vehicle application.  Get the hint I don't know your perfect Air / Fuel Ratio or know what Ford says it is, just follow basic tuning philosophies.  Remember, it cycles threw this Flow chart 100 to 4000 times a second.

These 11 branches dictate fuel, timing, and emissions, so lets get to it; for further information on why click here: Strategies

Strategy	Fuel Control	Spark Timing Additions	Emissions	Sensors in Use
1 - Start / Crank	Open loop, 2:1 A/F	TFI controlled	None	PIP / ECT
2 - Cold Start & Warm Up	Open loop, set enrich values	ECT	Air to CAT	PIP / ECT / ACT / NDS
3 - Cold Drive-Away	ECT < 170° = Enrich ECT > 170° = Lean	RPM  / Load	Air to CAT	PIP / MAF or MAP/ ECT / ACT / TPS
4- Warm Drive-Away	ECT > 160° = Lean ECT > 185° = Enrich	RPM / ECT / EGR / Load	EGR Can purge Air to CAT	PIP / MAF or MAP/ ECT / ACT / TPS / EGR
5 - Warm Idle	Closed loop, 14.7:1	Retard after 1 minute	Intermittent Air to CAT	PIP / MAF or MAP/ ECT / ACT / TPS / EGR / NDS / HEGO
6 - Warm Cruise	Closed loop, 14.7:1	Approx 20 degrees	EGR Can purge Air to CAT	PIP / MAF or MAP/ ECT / ACT / TPS / EGR / HEGO
7 - Part-Throttle Acceleration	Closed loop, slightly richer than 14.7:1	Load / RPM / ECT / ACT / EGR /	EGR Air to CAT	PIP / MAF or MAP/ ECT / ACT / TPS / EGR / HEGO
8 - Full-Throttle Acceleration	Open loop, set maximum A/F ratio	WOT Values; approx 30 degrees; back off if KS indicates	None	PIP / MAF or MAP/ ECT / ACT / TPS / KS / VSS
9 – Deceleration	RPM > 1500 = Ø RPM < 1500= 14.7:1	Set Advanced Value	Can purge	PIP / ECT / TPS / VSS
10 –Failure Mode	Open loop set by last ECT signal	Set by last ECT signal and RPM	None	PIP / TPS / MAF or MAP
11 –Limited Operation Strategy	Open loop 14.7:1 from last MAF or MAP signal	Base 10	None	PIP

 

EEC’s use two different programs and sensors to indicate engine Load.  Engine Load is the amount of work the engine must do to accomplish a task.  Wide-Open-Throttle from a stoplight is the greatest load.  The two different styles of load measurement are Speed-Density, and Mass Air Flow.  Speed-Density uses intake manifold vacuum and engine speed to estimate the volume of air entering the engine and engine load.  The EEC programming uses a MAP sensor and look up table to determine the amount of gas to send to the engine.  Mass Air Flow systems actually measure the mass of air with a MAF sensor with relation to the ACT sensor.  EEC Mass-Air systems can sense engine modifications and still work great.  The downfall of Speed-Density systems is a 460 will have the same Wide-Open-Throttle vacuum as a 302.  While the 460 has a very different Mass Air requirement.  The downfall of MAF is it will sense airflow in both directions, so air pulsations from wild cams cause problems.

 

Now lets talk memory, the EEC has three different kinds of memory, ROM KAM & RAM.  Read Only Memory or ROM; this is the long-term memory where the master program is kept.  The ROM cannot be altered and lasts 20 years after the EEC is disconected from voltage.  Keep-Alive Memory or KAM; this 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 from this one drive.  Once the key is turn off the RAM is deleted.

 

EEC-IV is currently our best “factory” engine computer choice today.  The best thing to do is write out a list of goals you wish to achieve, and see what it takes to achieve them.  See what aspects of your goals are not so important.  Power, Streetability, Fuel milage, ease of installation, passing emissions, ease of repair, and the almighty dollar are all factors you need to think about.  Many people don’t realize the big picture until the picture doesn’t work or costs alot.  Plan ahead, ask experienced tuners, racers, and talk to your friends.  As a good friend always asked me, “speed is money, how fast do you want to go?”

If you are new to EEC and want to start form scratch go here:

NEW TO EEC-IV

If you have an EEC-IV and want to make it better go here:

MODIFYING EEC-IV

 

EEC-V

EEC-V and EEC-IV are alike in a lot of ways, we'll skip to the changes.  EEC-V is faster, has more capabilities, and has an easier to change programming.  EEC-V has a lot of the same programming just harder to read it.  EEC-V is 18MHz that’s 18,000,000 tasks at once.  For aftermarket needs this 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 for more sensors and actuators for growing beyond just engine and transmission control.

The new EEC also had to apply to new government regulations, these were labeled as “On-Board-Diagnostics II,” and they required a new test plug called the Diagnostic Link Connector, all brands had to use this, and it has to be within reach of the drivers seat.

This connector makes inserting a chip into the EEC obsolete.  Ford uses this connector to “upgrade” you’re vehicles program, just like a home computer.  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 search 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.  Listen for future technology.

 

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