BMW Air Filters – things to know about ‘performance filters’

One thing that I cannot explain enough to people is that there is no way in hell you’ll feel a significant change in horsepower in your BMW by switching to a different kind of air filter.  The most popular of which is K&N filters, which are more of a screen filter with some foam that utilizes a special oil to help it filter.  Your local auto parts store will usually have some sort of demonstration with a ping-pong ball that floats higher over one of these filters when compared to its stock counterpart.  That’s all fine and dandy, but the last time I checked, there weren’t any ping-pong balls in my engine bay.

I’ve also seen many graphs when one of these filters are installed, and the car is put on a dynometer with the end result being a gain in horsepower and torque.  Before getting all giddy, these ‘gains’ are usually about 3-5 horsepower on an engine that produces over 250hp, giving an end result of about a 1-2% gain from that $65 filter you just bought.  Remember too that dynometers have a certain margin of error that can produce a different result through many tests. With any modification, I want to feel it in my seat.  The only way you’ll feel one of these filters in your seat is if you were to put it underneath your butt.

They also create problems for your engine management system as well as your valve train.  These filters are usually soaked in oil to capture the smaller particles that would normally be captured by a traditional air filter.  The oil does a great job doing this, but the engine will naturally suck that oil, with the particles in it, into the combustion chamber a little at a time.  That oil will basically coat anything in its path and cling to it.  On modern BMWs the main concern is that of the air metering device, which will either be an Air Flow Meter or an Air Mass Meter.  Neither of these likes to be dirty, and can result in false data being supplied to the brain of your BMW, or DME as it is commonly called.  Another long term effect of using these filters will be dirty intake valves which will drop your engine’s efficiency.

Keep in mind that with any modification, there can be positives and negatives when you look at the big picture.  I love getting more performance out of my BMW as much as the next person, but there are many things to consider when making any sort of modification.  As a general rule, increased engine performance will usually result in a drop in reliability and longevity.  If you want a significant horsepower or torque increase that you can feel, I would start with a performance engine management chip or a flash download on your BMW.  Changes in the computer can give you significant gains that can be measured, and felt in the seat of your pants.  Changing to a ‘performance’ air filter will only leave you with a few dollars less in your wallet, and an engine that is slowly getting bombarded with dirt and oil instead of clean air.

Chris Keefer

Independent Motorcars

5836 Autoport Mall

San Diego CA 92121

858-455-5836

www.independentmotorcars.com

BMW Inspection II – The Major Tune-Up

If you are driving around right now and the words ‘Inspection -3458 miles’ shows up, chances are that you are due for a major tune up or Inspection II.  This is another example of what I call the BMW language barrier.  I grew up in New Jersey.  In New Jersey when you need an ‘Inspection’ that means you’ll be heading to the local DMV testing station where they test your brakes, lights, and run an emissions test.  In California, ‘Inspection’ means nothing, so many ignore it.  What it should read is ‘Tune-Up.’   Some ‘places’ have an interesting philosophy as to what should be done during the Inspection II, these same ‘places’ also tell you that you only have to change your oil every 15,000 miles.  So, what exactly constitutes a proper tune-up on a BMW??

What we try to do during the Inspection II, is to change every single servicable item on the car that we can. We recommend this service about every 25k miles or every 2 years. The meat and potatoes of this is typically the following:

1. Oil change, transmission fluid change, differential fluid change.

These are the three basic fluids that allow the car to keep moving.  On the side of every BMW transmission you will find the words “Lifetime Oil.”  Which means that you never have to change the fluid, as it is good for the lifetime of the transmission . . . . well . . . all that means is that when the transmission dies that the fluid is still in there.  See where I’m going with this?  It is essential to change your BMW transmission fluid with every tune up to increase the ‘lifetime’ of the transmission.  Transmissions range from about $4-6K installed.  If you can get another 50-75k miles out of the transmission by simply changing the fluid, it’s worth it.  The differential allows the rear wheels to turn and also can benefit from fresh oil and the engine oil change is part of every tune up.

2. Spark Plugs changed and valves adjusted (when possible).

Some cars, mostly older, have adjustable valves.  Having the proper valve clearance is essential to how your BMW performs.  If valves are too tight, or too loose, it can damage the engine.  The spark plug issue is a great one.  Spark plugs are good for about 30k miles tops.  Many are of the opinion that they last for 100k miles, which they can, but not without costing you.  Time after time I review customers’ past bills and I see that they have bought ignition coils at about $90 a piece.  The ignition coils allow the spark plug to fire while the engine is running.  What I never see on those bills is the purchase or installation of new spark plugs, which cost about $16 a piece at the high end.  What has happened is that the plugs are so worn that the coils are continually stressed out and ultimately fail in their efforts in getting a limping spark plug to keep firing.  I’d rather spend $16 on a plug, than $90 on a coil — plus my engine will run better.

 

3.  Air filter, Fuel filter, interior microfilter

These are all basic items that promote clean air and clean fuel.  The interior microfilter cleans the air that enters the passenger compartment.  I’ve seen these filters so clogged that barely any air will come out of the vents when the A/C is on.  If your car has a funky smell when you have the A/C on, chances are that your filter is bad.

In addition to these items a good Inspection II should also provide an inspection of the entire car.  Check the suspension, check the tires, look for alignment issues, and check the brakes.  Check all mounting points for the engine, transmission and differential, as well as inspecting the driveshaft for any faults. A general look at all the safety items to make sure that they are functioning properly (but we don’t test airbags).  Generally you want to have all the door hinges lubricated and the weatherstripping treated with protectant.  We also scan every single module on your car to see if there are any issues worth investigating, and re-set your ‘Inspection’ light.

What is most important is that the technician that performs your Inspection II is familiar with your car and the possible issues that may arise.  Like I said before, I’m not too privy to Mercedes Benz and the different issues that certain models have.  What I am able to do on any BMW however, is to zero-in on areas of the car that are known to present driveability or safety issues, and address them accordingly.  Knowing how to change all of the tune-up items is great, but knowing the car you are working on is so much more valuable.  It allows me to give you a detailed report of what your car needs now, and what it might need 6 months from now, allowing you to plan ahead instead of getting hit with a big repair bill at a bad time.

A proper Inspection II Service is probably the best thing that you can stay committed to during your ownership of a BMW.  It keeps the car efficient, well tuned, and most importantly, you’ll be well informed.

Chris Keefer

Independent Motorcars

5836 Autoport Mall

San Diego CA 92121

858-455-5836

www.independentmotorcars.com

 

Spark Plugs are Spark Plugs on a BMW, Right?? WRONG!

If you are inclined to change your own spark plugs on your BMW there are some things you need to know before heading out to the local auto parts store . . . just cause it’ll fit, doesn’t mean that it’s correct.  There are many areas of the auto parts industry where quality and sound advice has taken a back seat to marketing and profit margins.  One of these areas is the good old spark plug.  I’m going to attempt to keep this simple and not too technical, which basically means you’ll have to trust me. (trust me, now that’s  mechanic line if I’ve ever heard one.)

When you go to the auto parts store and order spark plugs for your 1985 535i they will have a neat little diplay that has about 5 different spark plugs ranging from what looks like a normal plug to one that looks like a space probe on the end.  The guy behind the counter will tell you your options, all of them with code numbers that make no sense and he’ll eventually tell you how great the platinum ones are with the 4 prongs at the top.   STOP!  You need to go in there knowing exactly what you need, and getting only that item.  Most people will get the platinum spark plugs by the way.

I used the ’85 535i as it takes a special plug, the Bosch WR9LS; a bit expensive as it has a silver core and the platinum plug that fits will probably be less expensive.  This car hates any other spark plug.  Spark plugs are funny things, they will all work, but not really work all the same.  When BMW produces a car, they go through tons of engineering testing and design, work out a fuel injection and ignition system and then specify a spark plug that will work best with this combination.  The guys at the auto parts stores look at a spark plug, figure out which cars it will fit, and then offer it for sale and push the ones with the highest profit margin.

Remember that your ignition system (this controls spark) has a specific design and was also designed at a particular time in automotive history.  If you own a 1972 BMW 2002, it takes a simple spark plug, there was no such thing as a 4 prong platinum plug in the early 70’s in mass produced automobiles so don’t use it.  The plug will not be optimized and neither will your car.  Plug gaps are also of importance.  In most repair books the specified gap will be the original gap provided by the manufacturer, some of which have changed.  It had been found that if you increased the plug gap for a 1990 325i it would result in a smoother idle as well as a boost in performance.  Regardless of what year your BMW was built, spark plugs should be changed during every Inspection II Service, which is BMW talk for the major tune-up.

Here’s a great link from NGK on ‘reading’ spark plugs.  The older your BMW the more this will apply, and BMW’s built post 1995 will barely apply to this information.  Good nonetheless.

Reading your spark plugs

Chris Keefer

Independent Motorcars

5836 Autoport Mall

San Diego CA 92121

858-455-5836

www.independentmotorcars.com