| The Oxy Sensor,
or OxySen, or O2 Sensor , or EGO sensor.: The Oxygen sensor has no function while an engine/ oxy sensor is cold. ( when hot it helps the ECU, finely adjust the air/fuel trim and mixture). My tracker , tells me I am in closed loop when the idle finally drops to normal (800rpm). (potentially that is ?) Some cars will drop out of closed loop at hot idle. ( older cars that have no OXY heater internally). THE OFF CAR TEST OF THIS SENSOR . See the on car test (official Suzi method). The best test for the OXY , is with a scope (1995 and older car) or with a OBD2 Scan tool (1996 and newer). See this page for some nice wave forms. Another nice page, showing 6 crosscounts per second as normal. The front sensors must: The front sensors purpose if for air fuel mixture , the rear is for the CAT-CON. monitor only. Some Spec.'s: GM states that the lean to rich transition should happen in 100mS and the rich to lean transition in 125mS. ( miliseconds, or .125 seconds ) So that would be 225ms (.225 second period) Almost 4 per second. The window of transition is 300mv to 600mv. (millivolts) ( or .3 to .6 volts) The engine must be hot and so must the oxygen sensor, run the engine at 2500 RPM from 2 to 5 minutes before the test. ON OLD CARS , the OXY sensor DROPS out at IDLE ! because it cools down too much. ( If it is electrically heated , it can hold Closed-Loop "CL" , almost all the time) [ and never at wide open throttle ] Have a SCOPE?: You do NOT need a DSO (expensive Digital Storage Scope) to check this sensor. ! Any old Oscilloscope can view a car sensor of any kind , if you need storage, a cheap digital camera will work perfect. Every photo I've made is good, just shoot the scope . Set the Horz. period to 1-second/div and the Vert. channel to 1 or 2 volts. I like old Tektronix scopes, because they have a fantastic horizontal sync. circuits. Makes looking easier and faster. I have a old 465 tek. that I got for $50. A cross count, is the number of swings, full periods, per second. Or just count the Humps you see on the screen. You can bleed air into the system at the Brake booster hose or inject Propane into the same place and watch the OXYgen sensor. You can the force LEAN or FORCE rich and watch the results. Before testing the O2 sensor on car , make sure the car is going into closed loop. " the ECU and the Oxygen sensor operate as a servo" Never place an ohm meter or any voltage to the sensor. (the sensor is really a tiny battery that varies with oxygen) 2 to 4 cross counts is typical, on older cars. The ECU can fully calculate the proper Air fuel ratio at all times with out an oxygen sensor, however it uses this sensor to fine tune the mixture. \ Dead O2? A dead (flat line) Oxygen sensor will cause the engine to run a tad rich. ( not a lot, just a tiny bit rich , If this is not true, you have more problems) The OXY was designed to act that way !,by default in its design ( there are exceptions !). Going lean under load, is not good for the engine , thus the design reason. One exception; is the deposit of MUD that lands on the outside of the OXY sensor blocking its outside Ambient Air holes, This is VERY BAD. (off roaders alert) Dust it off carefully. No solvents here, ok? Pouring oil , or solvents down the intake of your car can kill any OXY sensor. "Like those dang, fogging oils and carbon out treatment, fish oil, oil foam, are junk, DON'T DO THAT !! How ever water injection will help to remove carbon from the engine ( google it ). Ok, the sensors bad, now what?: DO IT YOUR SELF (DIY): One can save money by buying a Bosch(tm) brand sensors, that has just pig tail wires on the end. (sometimes). You must get a color code cross reference for this method to work. ( Bosch has the pin out on their web site, see links below) The signal levels are very low and the connections must be perfect , in fact , I recommend using solder and special flux and heat shrink tubing. The Bosch Universal sensors come with a splice kit, you can try that. Or get fancy with solding , methods: I use Kester SP30 past flux ( it has "zinc chloride" so keep it away from kids and the goats). This special paste will solder the special wire on the sensors. I think the wire is Stainless plated or something like that. ( rosin core flux, does not work at all) Just skin the insulation back , place the Heat shrink tubing , twist the wires together and flux them , then solder with any iron. After the splice clean with Alcohol the junction of all flux, it is corrosive and needs to be so. optionally, put some silicon RTV sealant on the wire before the shrink operation.a You can shrink it with a cigarette gas lighter , ( I use a heat gun). There are other , ways, one is a FUSION splice. The above is cheaper, easier ,and very easy to get the parts. Most people have a soldering iron, so all you need is the paste and shirk tubing. this document may help. FUSION: http://www.decagon.com/appnotes/WireSplicingandSealingTechniqueforSoilMoistureSensors.pdf Even Ace hardware has the shrink spice tubing. I put RTV sealant on the inside before sliding the tubing over the junction. You can save $100 per sensor doing this yourself over buying OEM sensors. But the prewired Bosch sensors sold on FleeBay are the best deal at about $50. Mouser electronics, has the paste: The correct paste is very important for a DIY job. NGK says this: http://www.ngksparkplugs.com/techinfo/oxygen_sensors/installation.asp?nav=32200&country=US BOSCH Data Base: Click here : At Bosch you can find the correct Sensor Data base: Nippon Denso makes them too and you can google that. (I always use Bosch , they invented it, and the price is good) FYI: (excerpts from Bosch) "Q: what can damage my sensor? A. An oxygen sensor can fail prematurely if it becomes contaminated with phosphorus from excessive oil consumption, silicone from internal coolant leaks, using silicone sealant in the engine, and some over-the-counter fuel additives. Even a small amount of poorly refined gasoline can kill an oxygen sensor. Environmental factors such as road splash, salt, oil, and dirt can also cause a sensor to fail, as can thermal shock, mechanical stress, or mishandling. However as required by vehicle manufacturers, Bosch sensors are designed and tested with these extremes in mind." Bosch quick lookup; ( non
California
FED 48 cars) JX model, front sensor only
[ the front sensor controls the A/F mixture, not the rear].
This sensor will cost $40-$50 (@Fleebay) to $65 RockAuto.com ( don't ask the dealer , ouch ! ok, $235? yah, each) At Rock auto the OEM style (plug and play) can be had for $75. So soldering would not save me time or money. Depends on the YEAR? However I look for discounts ,on Fleebay and find them. I am not affiliated to any stores or links in my pages ! My information is 100% free and I will not accept any money. First I find the correct Bosch PN, then I do would do widewide google searches to find them. A New Oxy sensor and new ECT can help your car achieve the maximum MPG possible , as designed. Replace them any time MPG drops. If I suspect a O2 being bad, I just swap it out. I can tell by 2 ways, MPG suffers , or I find it toggling slowly on my OBD2 scanner Graph. I hope this helps someone and saves them $ rev.2 8-26-2008 edit data and verbage. externalized it for easier viewing and maintenance. |
