Obd Explained

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In 1996, On Board Diagnostics went into its first revision: OBD2. The goal was to produce vehicles that emitted less toxins into the atmosphere. While good for the ozone layer, their are several problems of OBD2 for tuners like you and I.

As most of us are well aware of, OBD1 is very easy to work with. P28 ecu's are a dime a donzen, cheap, and many "programs" exist for it, such as the Skunk2 or the Mugen program. As you may have noticed, it's rare, if not impossible to find a program for an OBD2 ECU. Let's take a look at the differences between the two versions.

First, and most obvious, is the plug playout. While irrevelant to anything actual electronic, it makes direct plug-n-play impossible without a conversion harness. In addition to the pin locations being different, there are some differences electronically.

The only electronic differences between OBD1 and OBD2 is that OBD2 has an additional O2 sensor located after the catalytic converter and a crank fluctuation sensor located near the oil pump. So why is OBD2 considered to be such a pain in the ass?

Basically, it's not. It's the plugs and wiring design that become the pain in the ass. OBD1 cars use a 2-piece harness. The engine harness plugs into all the sensors, and then plugs into the shock towers on either side of the car, which go into the chassis of the car. For the most part, OBD2 cars are 1-piece harness. The wires plug into all the sensors, and then goes straight through the firewall into the ECU.

OBD2 is simple to use if you are putting an OBD2 motor into an OBD2 car. It's when you put an OBD2 motor into an OBD1 car that custom wiring comes into play.

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