Hello,

Does anyone here have experience with the EZL (ignition) system on 560 M117.168 engines?

On non-US cars, this resistor is actually a potentiometer or rotary switch. For US cars, the resistance is fixed to 750 ohms.

My understanding is that in our 117.968 (560SEC) engines, the 750 ohm resistor gives us 3-7 degrees advance at idle, and 24-28 degrees at 3500 RPM (which is where our motors produce the most torque). Would there be any gains in torque by advancing the ignition even further? How much tolerance do you think MB programmed in to allow for 91 octane pump gas?

My guess is that a lower resistance would increase/hasten advance, but I can't be certain. Assuming I do try to change this value by substituting a potentiometer, is there a safe way to experiment without "pinging" my engine to pieces? Maybe I should get some octane boosting additive before I try this.


Here's the only reference I see to the R16 resistor in the MB CD-ROM manual (paraphrased):

-vacuum advance is activated at idle speed (not a fixed curve). The reference resistor is also active at this speed (without vacuum).
-when the coolant temperature rises above 95C, certain ignition curves are retarded to prevent engine temperature from rising.

As you can see, the manual is vague about the purpose of this resistor.

I have observed that making the resistance infinite (open circuit) causes the idle to smooth and rise about 75RPM. This is advance, right?

Thanks,
oktane