This page describes how the hardware in an ECU works, and fun things you can do with it. If you are just wanting to learn how to chip your ECU, you should look at What You Need instead. If you are looking for detailed information about what is going on inside a particular program, you might want to look at Rom Maps.

Honda definitely did not reinvent the wheel in terms of ECU technology for each new motor they released. Each "family" of ECU generally shares one or more PCBs that are populated with different components in order to run different motors. This really opens the door for ECUHardware Mods. Additionally, there are design peculiarities that carry over from one family to another.

ECU Families:

• OBD0 Vacuum Advance ECUs from pre-88 cars lacking electronic advance distributors share some common features.
• OBD0 DPFI ECUs from 88-91 cars are useless bastards that are 2 injectors short of being useful
• OBD0 MPFI non-vtec ECUs from 88-91 are a definite family.
• OBD0 Vtec ECUs like the PW0 and PR3 are a definite family.
• OBD1 Civic Integra ECUs are a definite family.
• OBD1 Prelude Accord ECUs are a definite family.
• V6ECUs from the Acura/Rover/Honda Legend V6 cars, NSX and (?) V6 Accord have many common features.
• OBD2 A ECUs are quite similar.
• OBD2 B ECUs are quite similar.
• OBD2 K ECUs are an evolution of OBD2B ECUs designed to run K-series motors

If you want to learn about how the Oki 66K MCU works, you should look at 66k Assembler Docs.

There are many ECUHardware Mods you can do to change how ECU hardware works.

Honda often used MCUs that had internal (on-chip) programs. These were often copy protected. There are Mcu Readers to defeat the copy protection.

Ever wonder who designed honda's ECUs? Kehein Indiana Precision Technology is to blame...

It is possible to switch between more than one program on your oversized EEPROM. All you need to do is add a pullup resistor to the extra address lines (A15, A16, Etc.), then to switch them, just add a debounced switch to the address lines to ground them.

Here is a diagram of 28 & 32 pin EEPROMS:

• EEPROM pinouts:
  

Attachment?:	Modify:	Size:	Date:	Who:	Comment:
1.32_pin-2-28PinIC.jpg	mod	39713	06 Feb 2007 - 01:39	Jared Karagen?	EEPROM pinouts