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4 Wire Oxygen Sensor

The factory one wire Oxygen sensor works well for what it was designed for but it does have limitations. 4 wire sensors have been used for a while so it is easy to find them at junkyards. It is easy to test a sensor to make sure it is working with just a voltmeter and propane torch. Take the sensor you want to use out of the car and hook your voltmeter up to the sensor wire and sensor ground wire using the chart on this page to figure out the wires. Once you have it hooked up you should be reading 0 volts. light the propane torch and hold the tip of the inner blue cone on the oxygen sensor. It takes a few seconds to get it up to temperature and you should see the voltmeter go to .9-1.4 volts. Once you get it there twist it around to make sure the whole element is heated evenly and any buildup on it is burned off. The voltage should drop within 1-2 seconds to under .1 volts when you take the propane torch away. If it does not go down quickly then try turning the propane up higher and burn off any deposits on the sensor you can. It will not hurt the sensor to make the case glow orange. After a few minutes of cleaning the sensor it should respond quickly to the torch being pulled away from it. If it is slow to respond to the torch being added or taken away then it is probably lead or silicon fouled and you can give up on it and go to the next one. If after 5 minutes it isn't working like it should then give up on it and pull another one off a different car in the junkyard. I would grab an extra one while I am at the yard just to have a spare they are cheap.

Knock Sensor

I was not happy with the way most knock sensor indicators worked. They really don't give much information. So I decided to do something different and wire the knock sensor up so I could hear it over the car's stereo. The idea behind it is simple the knock sensor is a piezoelectric device that generates a small electrical current when it is vibrated. Pretty much the same as a microphone but able to withstand temperatures much better than a standard mic.


I started by removing the rear seat, rear seatbelts, all rear plastic parts, soundproofing from the carpet, and tar soundproofing. I then used thin automotive carpet and spray adhesive to glue the carpet over the bare metal. The carpet is very light and the total weight of the carpet and glue is not even one pound. The improvement to the look of the interior over the bare metal is definately worth the extra weight. The car is also much quieter with the carpet compared to bare metal. These pictures show the interior without the front seats but I put the stock front seats back in for now. I left the mounting hooks for the seat back in place, I can lay the seat bottom in place and hook the seat back on those hooks in case I want to take more than one person somewhere.

Front Bumper

The Front bumper has been modified by filling in most of the grille, adding an air dam, and by sealing the gasp at the hood. The less air going into the car or under it the better your aerodynamics. The radiator really doesn't need that much air but if your car gets warmer than normal then you might want to slightly open up the opening for the radiator till it gets back to normal.

Old Hatchback Modifications

I am listing all the mods done to the car while it was still a hatchback. Some of the modifications have linked pages showing more detail but a lot of these mods don't need much of an explanation. This list was my basic starting point…

Rick's Metro XFi

Welcome to the page for my Geo Metro XFi. Check out the pages in the top left box for a list of the things I have done to improve the mileage of the car. The gas log shows the current mileage I am getting as…