One basic tune-up procedure for just about any car on the road is the replacement of your spark plugs and spark plug wires. I recommend examining your spark plugs every 30,000 miles and as the car ages, it'd be a good idea to check them more frequently. If you see signs of burnt electrodes, oil, etc., replace them. In reality, you can probably go longer than that, (most manufacturers recommend an interval of 100,000 miles) but, you never really quite know how long the plugs are going to last. A lot of factors can contribute to the plugs wearing out faster than you might expect.

On the M104 engine, Mercedes has eliminated the use of a distributor by integrating a “wasted spark” ignition setup with three coils. In a wasted spark system, the spark plugs fire in pairs even though one plug is on the compression stroke and the other plug is on its exhaust stroke. The extra spark on the exhaust stroke has no effect and is considered to be "wasted." The main advantage of using this setup is that there are half as many components needed for the engine and thus less expensive to produce.

This project should take an hour or less with minimal tools. Want to replace your plugs this weekend? Shop here for spark plugs for your Mercedes-Benz.

Let us know what questions you have!

 

Hi
I have just changed my spark plugs, 35k, on my slk 171, 2010 , 184 bhp, and they are Bosch plugs Y6npp3320
And I set the spark plug gap to 80 thousands of an inch
Instead of 0.8mm
And my mpg has dropped down by 20%
I first thought it may be the colder weather in England, but it is probably the gaps to small