This page describes the basic process for getting your car setup for speed density operation with ECMLink. If you need a more general speed density tutorial, then the Speed Density 101 page may be what you're looking for. In fact, we're going to assume you already know everything off that page as we discuss items below. So it might be a good idea to read over it even if you're already pretty familiar with SD in general.

The first step is to connect your sensors to your ECU. You'll need a GM IAT sensor and an absolute pressure sensor. The following two sections list the supported sensors. A good source for the GM sensors might be GM Parts Direct. We also really like the EFI Connection for GM connectors.

For addition wiring and/or pinout information, please refer to our ECU Wiring Information page.

You must connect your IAT sensor to the ECU's IAT input. This is the only input that's compatible with the speed density logic inside the ECU.

You'll want to use pin 72 (red w/blue stripe) on a 2G ECU harness or pin 8 (green w/orange stripe) on a 1G ECU harness for this. Or, more likely, you'll want to use those wires off the MAF harness under the hood as that will probably be a lot more convenient since that's where the IAT sensor is actually being installed. The wire color is the same on the MAF connector as on the ECU harness.

The IAT sensor has two wires coming out of it. Either wire can be connected to the ECU's IAT input.

The other wire should be connected to the ECU's sensor ground. That would be pin 92 (black) on a 2G ECU harness or pin 24 (green w/black stripe) on a 1G ECU harness. This can also be pulled from the MAF connector under the hood. The wire colors is the same on the MAF connector as on the ECU harness.