Does anyone know a rule of thumb in determining MON from RON? The gas I fill up with is 98 RON. I know RON is higher than MON but not sure how much in general. Gas stations don't know what the MON is and I wanted to get the (MON+RON)/2 number to determine whether I can get away with permanently driving without the resistor for more ooomph.

I did take it off today though and drove around the block. Didn't notice any difference. Haven't taken her out to the highway to do some high speed testing late at night but will do so later on. Didn't want to do that until I can somehow arrive at a theoretical octane rating of the gas I use so I know (at least theoretically) that I'm safe without the resistor.

I didn't notice any pinging though...either that or I don't know what pinging sounds like.

Cheers!

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Hi Ricky- on the web there is some type of FAQ or article re: "all you ever wanted to know about gasoline"...maybe of help to you

there's also one floating around, like "all you ever wanted to know about motor oil"

-fad

Ricky,

You didn't hear pinging, nor will you ever- an M119 has a knock sensor in each cylinder bank, so long before you'd hear an audible ping/knock, the engine will have already detected it and retarded timing. FWIW

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

-fad,

thanks! that was an interesting read. although it seems to point out that there is no way to derive MON from RON other than actual lab testing/analysis or asking the manufacturer.

michael,

you do realize that the ONLY reason I insist on posting queries on these boards instead of emailing you directly is to make you look good, right? Thanks!

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Ricky, My AMG manual specifically requires 98 RON minimum. No mention of MON so I just use BLAZE (97+ RON) and add a bottle or two of NOS Octane booster to be sure. You 500E will be similar.

When I was using other brands of fuel(95 RON), I definitely felt my car getting slower. No doubt my EMS was dialling in a few degrees retard.

You might want to read my post on having a cabin switch to manually activate your Aux Fans. The heat in Manila is terrible, especially if you get caught up in traffic. High temps=more likely knocking.

Cheers

Bong,

Thanks for the heads up. I too always load up with Blaze. Will check for ways to increase octane by a point or two. Do you know of a lead free octane boost?

Also, I just checked my manual...it says I need 91 octane (RON + MON)/2. It also specifically warns against the use of additives... Hmmm.... Gotta figure this one out...

After replacing my wiring harness, temp sensors and putting in JimF's temp sensor pigtail, the 500E never goes past 100 anymore. I think I'm pretty okay in that area. You might wanna check it out...

Thanks, Bong. Hope you see your C36 at some point...

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Ricky, I am partial to NOS Octane booster, although it is more expensive ($11.00 per 12-oz can) than STP or Gunk. All are suitable for our cars but steer away from products that contain alcohol. I read they promote corrosion in the fuel system because they are hygroscopic.

So you changed wiring harness too eh? Blasted biodegradable wiring harness... I paid 41,700 for mine.