Look at Kleemann's post in this section -- it advances the timing giving more midrange torque

 

Kleemann's post -- (one doesn't need to translate an MBUSA setting from Euro specs) 93 is 93.

 

I'm in Canada but ours here is similar to the European settings.. for octane.. very very simaliar.. actually the same.. i was just told to put in the best.. some gas stations have 91 as highest.. some have 93.. so i would guess it would be just the same...

 

i read it already and didn't really understand it... so i need a dummy explaination...

 

if you have 91 or 93 as the highest grade, then they must be using the same scale as in the States - (R+M)/2. Otherwise you'd see numbers like 95 and 98.

 

I read it very carefully. However, the Star Diag computer clearly says "93RON" etc. RON is not used in the US to measure octane numbers. (RON+MON)/2 is, instead. Hence, the conversion.

It could be a glitch in the Star Diag software - to display incorrect scale designation for the US market - but it sure seems to be one of the things that keeps this debate going.

 

whatever..

 

I'm pretty sure vadim's right, we had this same discussion a couple of months ago. Somewhere on this site (I'm too lazy to look) someone has posted screen-shots of the computer settings from the Star Diagnositc computer. It specifically shows octane as RON (although this could be incorrect as vadim has speculated). Base is probably the setting for using 95 RON (91 US).

Cheers, BT

 

Setting 2 is 93
Setting 1 is 91
Base at least 89

 

Now that we see that the computer shows "At least 93 ron" which equals 89 Octane in the U.S., wouldn't it make sense that the "BASE" setting = 95 RON?

The computer has 89 RON, 91 RON, 93 RON, and then BASE. By following the pattern, I'd guess the next step up would be 95 RON. (Number increases by 2 everytime).

The owners manual says "Car needs 91 Octane or greater".

Since 91 Octane = 95 RON, this also implies that BASE = 95 RON = 91 Octane just like the manual says.

Even the computer screen shows that "This correction is used to retard the ignition timing in order to prevent the engine...fuel is poor".

IMO, I'd leave the setting as is.

 

It says values of ron at least 93 octain. not 93 RON.
Randy

 

Notice the screen shot says, "the correction is used to retard the timing to prevent the engine...when the fuel is poor." This implies that all of the corrections retard the timing - there isn't one to advance it for better fuel quality and that base is for 95RON/91 US.

I was inspired to find the other thread on this same topic:

https://mbworld.org/forums/showthrea...&threadid=6756

BT

 

I agree with your reasoning. I would like to know how our bureaucrats came up with that stupid average of RON and MON crap. I propose that we call it the Stupid Obnoxious Bureaucrat's Octane Number or SOB'sON for short.

 

So, if by chance a larger crank pulley makes your car ping because of crappy gasoline in your area or high heat it may pay to have it set to 93 or 91 to retard the timing a little bit to prevent the ECU from retarding it a lot at high RPM. Or is the ECU adaptive enough to figure out that you are pinging now and then and adjust the timing curves on it's own.

 

Randy - could you please post a screenshot with the "base" option highlighted? That might put an end to endless speculations (if it shows the octane number it represents, that is).

 

The term "octane" is used in RON

Research
Octane <---
Number

This leads me to believe that they are using RON units even though it reads "octane" in the pull-down. Europe octane is measured in RON and ours is xxx... Either way, it's still considered OCTANE and that's what's shown on the pull-down. I think KJ-Type R is correct.

RANT: How many people work in Mercedes engineering? And NONE of them read this board????? Nobody can help us here?!? WTF!?!?

 

There is no confusion here at all. If you have a ping problem that is caused by poor fuel you retard the spark. the top setting allows for the most advance for 93 Octane or better. the second setting less advance for 91 Octane and so on.

Randy

 

I think the confusion is that, is the 93 on that menu screen RON like what they sell in Europe or (RON+MON)/2 like what the pumps in the U.S. sell? The confusion is that is says RON on the screen but some think it's (R+M)/2. If this is the case, what is BASE, is that the default the car comes with? Is it RON 95 as some speculate?

BTW, you have a pulley, what octane fuel do you use and do you have any issues with it?

 

Thank you for your professional input! This should cease the confusion about advance or retard at the very least.

Just as a side note: when was the last time anyone saw 83 octane gas at the pump??? The last time I saw gasoline this poor I was in South Korea.

 

and what have we learned class.

USE THE BEST FREAKING GAS YOU CAN, AND LET THE ECU MANAGE THE IGNITION.

 

I run settings for 93 octane and fuel quanty setting of 3. I saw that some with the chip set were haveing ping with the chip I wonder if they had advanced the timeing in the ecu settings in addition to the chip? Side note Renntech is working on a flash program for the ecu that does not require installing an on board chip for the Simmions ecu. There is alot more to the ecu programing than fuel maps and timeing....

Randy

 

Not everyone has learned so far. Some people are so stubborn, they won't listen!

 

[QUOTE]Originally posted by avlis
[B]

The term "octane" is used in RON

Research
Octane <---
Number

This leads me to believe that they are using RON units even though it reads "octane" in the pull-down. Europe octane is measured in RON and ours is xxx... Either way, it's still considered OCTANE and that's what's shown on the pull-down. I think KJ-Type R is correct.

So?
M = motor
O = OCTANE
N = number

 

MON = Measured Octane Number

 

WRONG! it IS MOTOR OCTANE NUMBER
http://www.faqs.org/faqs/autos/gasoline-faq/part1/
Its a long boring read, but it is correct.