Your BMW probably has two oxygen sensors, but might have as few as one or as many as four. These BMW parts operate together to give the onboard computer a clear indication of the composition of the exhaust.
As the exhaust flows over these sensors, they send voltage to the computer. If the oxygen content is high, then the voltage drops. The computer ?knows? that the mixture is lean, so it sends more gas to the engine. If the oxygen content is low, the voltage rises and that means the mixture is too rich. The computer will cut back on fuel flow to correct the problem.
Even when driving a steady speed, the fuel/air mixture will fluctuate as conditions change. When accelerating or decelerating, the mixture changes rapidly. The computer must be able to respond quickly so that the engine runs at peak efficiency and auto emissions are kept to a minimum.
The Problem With Aging Sensors
Like other BMW parts, oxygen sensors don't work as well as they age. The sensor eventually becomes coated with soot and residue from the engine exhaust. This has two effects.
First, the sensor becomes sluggish. It can't react to changes as quickly and it has trouble "seeing" the air through the buildup. That means the computer isn't notified as quickly and fuel flow doesn't change like it should.
Second, even when the sensor does respond, the buildup causes it to see less air than actually exists and therefore reports a lean mixture. This causes the computer to send more fuel to the engine than needed. This not only wastes gas but also causes the car to belch out more harmful emissions.
Over time, the rich fuel mixture will put strain on the catalytic converter. It has to work harder to knock out the contaminants and as it works it heats up. The converter can actually become hot enough to melt the catalyst, causing a blockage in the exhaust and an expensive repair bill.
When Should The Sensor Be Replaced?
Most people learn their oxygen sensor is bad when they fail their emissions test. If you live in an area without emissions tests, you may not find out until serious damage has been done.
These BMW parts should be replaced as part of routine maintenance. The schedule ranges anywhere from every 30,000 miles for the oldest technologies to 100,000 miles for the most current. Check your manual or talk to your mechanic.
A car with a bad oxygen sensor can burn 10-15% more gas than normal and that adds up. The cost of replacement will be made up in no time by your increased fuel efficiency.
As the price of fuel goes up and up more drivers are thinking about using generic gas from stations that are not affiliated with the big international gas companies like Exxon or Shell. The question is, can you get the same quality of gas from ABC gas station as you can get from the big guys? Will the XYZ gas run your car with out causing damage to your engine?
The answer plain and simple is, there is not much difference between the generic gas and the branded gas other than some additives which each company has added to it's gas. To really understand why it is so similar a quick look at how the gas refining system works makes the picture clear.
By and large gas produced at refineries is a generic product. An example often used to illustrate this is California because it has a standard different from most other states. In California all gas sold has to meet specific environmental specifications. Because of that all gas in California terminals are produced to the same specifications. Since all the gas is the same, gas refiners often share and exchange gasoline and store it at shared terminals in common tanks.
The gasoline that is produced at one refinery is not really different than another refinery. They all produce what one would call generic gas. It is the chemicals that are added to the generic gas that makes one brand different from another. Each brand has it's own formula of additives.
Such blending or adding of these brand chemicals or additives typically takes place when the gasoline is being loaded into a tanker truck for further distribution. In other words all the brands are starting with essentially the same generic gas as their main component. So generic gas is basically the same as the branded gas.
Just to make sure, studies have been done to see if there is a difference between generic gas and branded gas. A cooperative study was done by ABC News and the Maryland State Comptroller's office.
Scientists at the Fuel Testing Lab performed a myriad of tests on generic and branded gasoline. The gasoline was tested for many things including contaminants like excessive sediments or diesel that might have gotten mixed with the gas. The scientists put the fuel into a special test engine to make sure that the fuel was all 87 octane. The chemists at the lab even made sure that the fuel was properly formulated for the current season as mandated by regulations.
The good news for the consumer is generic and branded gas had nothing but minor differences. They found that by and large the gas was one and the same. The primary difference between competing brands of gasoline is the amount of detergent or additives the distributors add to it. Even then the differences are small.
So basically gas is gas and all the gas sold in stations whether it is from a branded station or a generic station will work just fine in your car. The biggest difference it turns out is only price.
It is reported that the average gas consumer could save between $100 and $200 per year by using generic gas. To save yourself some cash next time you fill up use the generic station.
Both Cyril Joseph & Scott Siegel are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.
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