DIY BMW Tune-Up
My 13 year old M3 is approaching 60,000 miles. In BMW vernacular, that means the car should receive an Inspection II service. An Inspection II involves a large number of things getting inspected (hence the name), but when you look at the work actually done it boils down to a general tune-up. Spark plugs, air filter, fuel filter, cabin filter and oil change.
Much of this work is straightforward and doesn’t require much mechanical skill. Instead of spending $800-$1,000 for someone else to do it, I’m doing the job myself. To make the job easier to tackle I’m doing the work in stages.
This weekend I replaced my spark plugs and air filter. This excellent, detailed video from Bavarian Autosport was a great resource:
The video shows the entire ignition coils being replaced, which is expensive overkill at this mileage. Replacing the spark plugs and the boots is more than sufficient. When you remove the old boot and place the new one on the new plug, you can feel a clear click as it engages. That’s the only thing I’d add to what is shown in the video, which is spot on.
My air filter is not stock. Soon after I purchased the car, I had a Conforti cold air intake (CAI) installed. The theory behind a CAI is that by making the air colder, it’s more dense. That increases the percentage of fuel combined with the air at detonation, meaning more power.
That’s the theory anyway. In reality the performance gain isn’t that much. Modern BMW engines (normally aspirated, not turbos) are very optimized stock, and harvesting power gains is difficult. My car has the CAI, a Conforti software download (known as the Shark) and a Dinan exhaust. All of that probably produces 15 extra horsepower, maybe 20 tops.
Unfortunately, after I had the CAI installed I never cleaned it. Periodically the foam filter needs to be cleaned and reoiled, and somehow it just never was on my radar. So the foam deteriorated to the point where I needed to replace it. Paying $85 for a new piece of foam with a metal funnel on the back was my penance.
Check back here soon for a report on the fuel filter and the cabin air filter. Last month I did my cooling system replacement and rear shocks, and was lucky enough to have a master mechanic give the underbody an inspection and a thumbs up. After this tune-up is complete, I’ll be a set of front shocks and a brake job from a total maintenance refresh on my car. (I did my oil barely a year and 4K miles ago so that can wait until spring).
And by then, it will be time for more preventative maintenance, or the unexpected repair. So it goes if you want your out of warranty BMW to run like new. But it’s well worth it, especially if you DIY the simple stuff.