This week we will talk about O2 sensors and air to fuel.

Convert to heated O2 sensor
Older cars use a standard single or two wire O2 sensor. They work pretty well but not well enough. To help gain some MPG and for the car to run better and last longer it should be time to convert to a heated O2 sensor. A heated O2 sensor is like a standard O2 sensor but has a heating element. O2 sensors work better when heated. Before the hot exhaust gas would heat the sensor for it to function correctly but your car would run lean or rich by time the sensor got to temp.

To convert to a 3 wire heated O2 sensor you just have to supply a 12 volt lead, ground and signal from the onboard computer. Some people use the 12volt lead that goes to the fuel pump but personally I would run a new line. All you need is some 16 gauge primary cable, a 5 amp fuse, a fuse holder, crimp ring terminals and O2 sensor extension cables. Basically run the 12 volt leads from directly to the battery. If you know what you are doing you can tap into the fuse box. Also remember the car's metal frame and body is ground but make sure there isn't any dirt or pint covering the metal that you plan to use as ground.

Depending on the car some use 2 sensors and others use 4. I've seen a few 4 cylinders that use three but they're rated for cali emissions.

Air to fuel gauge
A air to fuel gauge gives you a read out on the exhaust fumes. It will tell you if the motor is running lean or rich. It retrieves the data from a O2 sensor. If you plan on getting a gauge you should use a dedicated O2 sensor. Any kind of O2 sensor will work but you will get a better reading with a Wideband O2 sensor.

A/F gauges range in price but you can build one dirt cheap. You can find the parts at the local radioshack or you can order them from digikey or even allelectronics.
Heres a diagram and parts list.

parts list
DOT/Bar Display Driver LM3914N
Voltage Regulator LM340MP-5.0
10 Segment LED BarGraph
Resistors (2.3k and 3.3k)
Mini Circuit Board
16-20 gauge wire

Hyper Milling done right
A few of us have looked into hyper milling. You can use any car just about. Problem is it can be very dangerous. When you turn off the motor and let the car coast the motor has stopped creating a vacuum. the Brake Booster will only have enough vacuum to stop the car one or twice or even just enough to slow down but not stop. To fix this all you have to do is take a trip to homedepot. What we will discuss here is a cheap easy way to make a vacuum reservoir. People have been using vacuum reservoirs in muscle cars and such when they toss in a huge cam. What this vacuum reservoir will be used for is the brakes.

part list
3inch diameter PVC pipe 6 to12 inch long
Two 3 inch PVC pipe caps
PVC pipe glue
One 3/8inch brass, copper hose barb with threaded end.
3/8inch hose, get three 3. Doesn't cost much and this way you can make sure you have plenty.(Buy at local car part store, vacuum hose or fuel hose can be used.)
3/8inch hose T fitting (Can find in the plumbing department or bought at the autopart store)
Three hose clamps

Drill hole into one of the caps for the 3/8inch hose barb. Use PVC glue to seal up the threads. Glue on both ends of the pipe.
In the engine bay of the car on the right side facing the engine you should see on the far back at the firewall a big round object. This is the brake booster. Theres a hose going from the booster the a vacuum port on the intake manifold of the car. Some where on that hose cut in half and add the T fitting. Use hose clamps to seal it. Attach the new hose you bought and connect the reservoir. Make sure the reservoir is away from the engine block and exhaust manifold.

This device will add more air to the booster so when you're coasting down the road with the motor off you can be sure it will stop the car once or twice. Bigger the reservoir the more vacuum is stored. Be careful, too big will cause the booster to not have enough air to function.

Nextweek: Cleaning the fuel system and routine maintenance.
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