How do I Connect an Air-to-Fuel Ratio Flowmeter?

The air-to-fuel ratio flowmeter is a gauge that measures the free oxygen content in the exhaust emissions of a vehicle. This gauge detects the amount or percentage of oxygen, and converts it into a specific voltage shown on the flowmeter's display. Most vehicles run on a 14.1-to-1 air-to-fuel mixture for maximum performance. But when parts are added on to increase airflow or horsepower, monitoring the oxygen flow becomes important. The air-to-fuel flowmeter can be used to tune the engine for different performance parameters. Connecting it can be accomplished with a few basic tools.

Instructions

1

Set the transmission selector in park, for an automatic and neutral for a standard. Set the emergency brake, and raise the hood. Use a socket and wrench to disconnect the negative battery cable. Look for a good location to install the flowmeter on your dashboard, that will allow you to drill a hole with a hole saw bit. Make certain no components exist on the other side of the dash panel. Depending on your meter's diameter, use the correct bit to drill the hole through the panel.

2

Route the meter wires through the hole, and pull them down under the dashboard for easy access. Slip the meter into the hole, and connect the mounting brackets on the inside of the meter. Tighten the bracket nuts with a socket. Splay the meter wires apart, so you can identify them. Look at the poles on the back of the flowmeter, and refer to its instructions. For instance, you will have a black ground wire, a red wire for the ignition switch, a white wire for dash lights and a violet wire for the signal wire -- which goes to the oxygen sensor.

3

Push the black wire (on the meter) through a rubber grommet on the firewall, and route it into the engine compartment. Strip the end of the black wire with wire strippers, and crimp an eyelet connector on it. Use a socket to remove a small engine bolt, and connect the eyelet to it. Insert the engine bolt, and tighten it with a socket. Push the violet, or "signal" wire through the same grommet, and route it to the oxygen sensor on your exhaust manifold. Check your manual, if you're not sure where these parts are located.

4

Unplug the connector that routes from the oxygen sensor to the electronic control module, also called the "power train control." Look for a "C", which denotes the signal wire. Check your manual to make sure you have the right one. Plug the connector back in, once you have found the C wire. Cut the wire at a position between the connector and the electronic control module. Strip both ends of the wire, as well as the end of the violet wire. Twist all three together, and twist a screw nut onto it.

5

Remove your fuse box lid, either located on a kick panel, under the dashboard or in the glove box. Find the fuse marked "ignition switch." Pull out the fuse if it is a spade type, or lift up one end of the fuse if it's a glass tube design. Strip the end of the red meter wire, and twist the end together. Place the red wire under the tube fuse and push the fuse down, or push the spade-type fuse down over the wire.

6

Locate the dash light fuse. Strip the end of the white wire -- or dash light wire -- from the meter, and place it under the tube fuse, or push the spade-type fuse down over it. Refasten the fuse box lid. Use electrical tape to secure all the meter wires to existing looms or convenient locations that will keep them neatly tucked away. Do not let the black ground wire sit directly on the engine block, but lift it up and away -- securing it on a bracket or nearby loom.

7

Reconnect the negative battery cable with a socket, and close the hood. Start the engine, and read the air-to-fuel flowmeter. You will see the needle fluctuate, as you press and let off the accelerator pedal.