TXTiger

I was searching the archives and saw a thread for optimizing the fuel settings for premium gasoline (basically advancing the ignition timing). Has anyone successfully gotten their dealer to do this? Did you see any increase in power? How was fuel economy affected?

TimmyC230boy

yes many people have gotten this done and have reported minimal if any change in power.

KJ-TypeR

There has also been some speculation that the settings actually LOWER the grade of fuel required by the car to allow the car to be sold in areas where only poor gas is available. This would mean that this change in setting would cause the car to perform WORSE than stock.

The settings might be in Euro spec (RON) which is a higher number than the numbers used by North America (RON+MON)/2.

e.g. 98 RON = 93 ((RON+MON)/2) (or something like that)

IMO, it'd be better to leave the setting as is.

Duffer

For the USA, I had the dealer put the ignition adaptive setting to 93 -- that will advance the timing the greatest.

I am still getting about 23-24 mpg as I break in the car so it can't be minimizing my mpg too much.

I was told that the base USA setting was for all grades of gasoline -- from 87 to 93 and that the timing won't advance as far at this base setting.

So it's up to you. I want as much power as I can get and if I am using Super Premium 93 anyway, I might as well get some power gain from it.

TXTiger

So changing the setting does increase the power? How much? Is it a perceptible difference?

Duffer

that it will give you some increase -- but I had it done at delivery so I cannot tell you if there is a perceptible difference.

But eventually I will get a alloy or ring pulley from Kleemann so I wanted to get the car prepped. But I may get anti sway bars first - this car has too much roll for my taste.

Brandon @ Kleemann

A person would have to have one finely calibrated butt to perceive the power increase. Changing the ign adaptive to premium (93 octane) allows 6 more degrees of total timing advance. Not much but something.

HERE IS THE IMPORTANT PART: If you use 91, its hot as all get out, oxy fuel etc- and the knock sensor "sees" incipent knock- you are back to "baseline" timing advance. This setting merely allows the ECU to TRY to run more advance. No one ever said it was the source of 50hp, bound to roll your eyes back etc.

With that said, however, ign advance is very important to mid range torque production. In theory the more advance to more tq (to a point).

The cars are set up to be able to dump 85 ocatne in a 10:1 CR engine and have it run reasonably well- why not maximize the settings since we are all responsible enough to use high grade fuel??

The set up screen on the MBZ DAS machine describes each setting quite clearly. "Baseline" (sub 87 octane) is recommended for "areas with poor fuel quality". Each sucsessive set up "requires XX as MINIMUM octane fuel".

Why an earth would an English language (North America specified) menu use EU octane enumeration?? EU issued MBZ DAS machines enumerate to 98 octane. These machines use the standards and values for the countries they are issued for use in.

vadim

there are 4 settings for the ignition: Base, 93, 91, 89. I was told that the "Base" advances timing the most, followed by 93, then 91, then 89. This means that changing from Base to 93 actually retards the timing.

KJ-TypeR

Now, who's right?

Kleeman or Vadim?

I was under the same impression as Vadim, but Kleeman seems to know something we don't. If someone could confirm what was correct, I'd tell my GF to get it done on her car, otherwise I'd rather leave well enough alone.

Duffer

Kleemann works on M/Bs for his living, he works on, purchases, modifies and sells several models of M/Bs so he has extensive knowledge of M/B and this car (since I believe he owns one), he is in the industry, seems to have inside knowledge, has an engineering background/education or has picked it up very well. . . .

I think . . .

KJ-TypeR

Anyone have pictures so I can show my dealer how to do it?

vadim

Does it actually have this text on the screen? The one at my dealer simply displays a drop-down list (Base, min 93, min 91, min 87 or 89 - don't remember) from which you pick one.
I initially had requested it to be set to "93", and had it that way for a while, but during my last visit to the dealer had them change it back to "Base". Quite frankly, I can't feel any difference. I use 93-94 octane all the time.

Would be nice to see an authoritative confirmation instead of guesses or opinions, since this issue is being discussed for almost a year now and yet there are more rumours than truth here. So far Kleemann has come the closest - I have every reason to trust him, but would like to him to confirm it.

KJ-TypeR

Currently, my GF's car is set at "Base":

Here is something interesting that I noticed:

When using Sunoco 92, my GF's car got 21.9 MPG consistently.

When using Sunoco 94, my GF's car got 23.4 MPG consistenly.

Now, since we know that advancing ignition timing (to a certain point) will increase power, AND increase fuel efficiency, it can be seen that the C230K's computer is compensating for 94 Octane in some way that causes gas mileage to improve.

This implies that it has automatically advanced timing since that is the only factor that could improve fuel economy.

From this, we can extrapolate that the advanced ignition timing has also lead to an increase in HP.

FYI: When advancing the ignition timing on my old car from 16-18 degrees, 1-3 whp was gained across the powerband.

Now, I am not sure if changing from Base to 93min would yield any increase in horsepower, if the computer advances the ignition timing the same amount in both cases. Perhaps setting it from Base to 93min allows even MORE power to be gained when using high octane fuel such as 100 octane racing fuel.

Duffer

[QUOTE]Originally posted by KLEEMANN
[B]


.... ign advance is very important to mid range torque production. In theory the more advance to more tq (to a point).

The cars are set up to be able to dump 85 ocatne in a 10:1 CR engine and have it run reasonably well- why not maximize the settings since we are all responsible enough to use high grade fuel??


Well, theoretically, I just think we ought to set the cars up for max performance even if we can't feel it. And it doesn't seems to affect my MPG

KJ-TypeR

Here's more of my thoughts:

Maybe Base = 87min

This would mean the 4 settings would be:
Base = 87min, 89 min, 91min, and 93 min.

Perhaps the computer has a range of ignition timing it can use to compensate for different grades of gas.

Since the lowest grade of gas widely available is 87, the car comes set at Base = 87 min so that the car will not ping/detonate if the owner puts in el cheapo gas (perhaps they are stuck at a gas station that only offers 87 Octane gas).

This setting might allow a range of gas to be used, starting from 87 Octane to say 92 Octane (a range of 5 Octane points).

As you increase the min octane rating, the highest Octane the car can take advantage of might also increase.

e.g.:

87min = 87 - 92 octane
89min = 89 - 94 octane
91min = 91 - 96 octane
93min = 93 - 98 octane

I wish someone had a C230K shop manual to solve this mystery once and for all.

TimmyC230boy

now what if you put a pulley on it. Will it be benificial to set to 93 octane if that is all you run anyway?

KJ-TypeR

Putting on a Pulley increases boost and combustion chamber temperatures.

As a result, the car is more prone to knock, ping and detonation.

If you increase the setting to 93min and the computer advances the ignition timing, you might find yourself in trouble as the ignition timing is set too high, which might lead to detonation if you have a pulley kit on.

Normally, the computer retards ignition timing to prevent ping, knock or detonation from happening. But by raising the the fuel setting to 93min, you might also limit the amount of ignition retard the ECU can do. Thus, your ECU might not be able to retard ignition to the point where your engine is kept safe.

We already know that a C230K with a pulley has to retard ignition timing at high rpm due to ping/detonation/knock. I'm afraid using 93min would prevent it from doing so, and thus compromise the safety of your engine.

Duffer

Kleemann, but if he is running his M/Bs equipped with the pulleys at the 93 ignition adaptive setting and counseling others to do so, I would think that there are no safety related problems

Duffer

like APR for my Audi TT 225 are coming out with software updates for a specific 93 octane setting. I am sure they are changing the adaptive setting to increase power.

When speaking with Kleemann previously, he counseled me not to change the fuel setting, but just to change the car's ignition adaptive setting to 93 for MBUSA cars.

KJ-TypeR

If the link I had posted in another thread is correct, and 93min is actually lower than the Base setting, the setting would actually be allowing ignition timing to have a greater range of "retard" than the Base setting.

So by setting it to 93min, your car would be able to retard ignition to a greater extent, thus allow your engine a GREATER margin of safety.

Duffer

I don't have time to learn about all this techno engineering whiz-bang stuff so I must read and listen to those who are in the know.

art_Ccoupe

so what u guys mean is to have the setting set to 93 octane.. and fill up the tank with 93 octane gas right? i would get better performance??

Duffer

but you may not be able to feel it with your "butt-dyno"

art_Ccoupe

ah.. icic.. but does it push more fuel into the car.. cuz i know it can be done with jap imports to increase at least 5 HP... and it's feelable.. with butt dyno's... i've done it b4.. i've tried it on my 735i.. i guess it was too heavy to feel the diff.. but i undid it.. *save gas*

vadim

Oh, yes... those octane numbers are RON (used in Europe). For the US and Canada they need to be translated into (R+M)/2 as follows:

(numbers are not exact, but close enough)

87RON -> 83US
89RON -> 85US
91RON -> 87US
93RON -> 89US

So, even at the highest possible ignition timing setting almost any octane grade would do.

Now, since the manual says that the minimum recommended octane number is 91 (which is ~ 95RON), it leads me to believe that that's what the "base" setting is. But - again- this is just a speculation.