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Discussion Starter #1
Been looking forward to having my car tested after removing the timing resistor. Comparing the emissions readings from 2 years ago when the resistor was still plugged in to now with it taken off shows dramatic emissions reductions with our ASM testing here in California.

On the 50/15 mode the emissions compare as follows

HC (in ppm) CO% NOx
2006
101 .27 745

2008
25 .04 389

And the 25/25 mode readings are as follows

HC (in ppm) CO% NOx
2006
43 .06 366

2008
17 .05 221

I was amazed at first with the dramatic power difference once the resistor was removed but wondered what the emissions result would be. So now I really wonder that the purpose of the timing resistor was at the time. I can't see any benefit of slower acceleration and higher emissions that result with the reistor in. Having read a lot on the plusses/minusses of the resistor I can't help but recognize the obvious, at least in my car. Think I'm gonna put the reistor in a display case and mount it in the garage................... Anyone else out there with a M103 engine that still has the resistor in??
 

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What is the timing resistor and where is it located? Does the 560 SEL have one? Is it safe to remove it? Ramesh.
 

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It's amazing what a proper ignition curve can do for combustion eh??? You should double check your timing, just to be sure you're not over advanced.. You want a max of 11-13 degrees @ idle.

The resistor is up next to the fuse box, #'s 2481 printed on it w/ some electrical tape wrapped around the bottom. Search, it's been discussed a fair number of times:)

I've always been a BIG proponent of running the full advance we can get away with..the Mercedes literature states these things are installed for one reason, "Poor fuel quality" which hear means some tard using regular.. No mind you, once you make this switch Premium is a Must!! Where as you can typically run regular with the resistor in place.

FYI, all of my cars are set up sans resistor and/or timing @ 11-13 degrees.

Jonathan
 

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Hey Ramesh, good to see you!
Are you having issues with emissions? I am up for an emission test soon, maybe we should try it if ours fail.
 

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So, the removal of this resistor specifically for 300SE/SEL's? Is it more about removing the resistor or replacing it? Is there anything that needs to be checked before going ahead with this?
 

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M103's, W116, 117's... Just check your timing once your done!

Jonathan
 

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I've heard the same thing, too. The resistor is only installed for the reason of cheap-skates putting low octane in the tank. When you remove the resistor, I believe it sets the timing to zero degrees. Shorting the circuit sets it to 12 degrees retard. Usually retarding the timing improves your emissions, but kills your performance.
 

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Pulling the resistor doesn't bring you to zero degrees, that would actually be Worse then having the resistor in place. Pulling it brings you to the maximum advance allowable based on your EZL, ie the most aggressive curve.

Factor in a few other variables and sometimes you can end up w/ a couple more degrees then you want, ie, my gray coupe come to 15 w/ the resistor pulled, so I have a wire in line that has enough resistance to pull my initial advance down to 13 degrees.


Jonathan
 

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How come???? Can't hurt a thing just starting..only if you have too much initial can you cause some pre-ignition/pinging while under load.


Jonathan
 

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I checked my 88 300SEL for this resistor and can't find anything near the fuse box. Does anyone know if the 88 has this resistor? Any help would be appreciated. Thanks,Vince
 

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I ran right out and checked my '84 380SE for this resistor......to no avail. It isn't on my car. Rats! I thought I could yank it out and help my car.
 

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Yes, All CIS E cars have them.


This is Only for CIS E Cars. You can set your timing the old fashioned way, ie turn your distributor housing. Just be Sure you have a timing light on hand!

Jonathan
 

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Pulling the resistor doesn't bring you to zero degrees, that would actually be Worse then having the resistor in place. Pulling it brings you to the maximum advance allowable based on your EZL, ie the most aggressive curve.

Factor in a few other variables and sometimes you can end up w/ a couple more degrees then you want, ie, my gray coupe come to 15 w/ the resistor pulled, so I have a wire in line that has enough resistance to pull my initial advance down to 13 degrees.


Jonathan
Yeah, that's true. Pulling the resistor should just apply NO retard. Aren't the resistor values the same for both the M103.981 and the M102.983 engines?
 

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I believe so... Somewhere bured in my computer I have the resistance to degrees retard chart..I'll have to try and dig it up.


Jonathan
 

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Got this from my 16v notes.

No resistor = no retard
2.4Kohm resistor = 2 degree retard
1.3Kohm resistor = 4 degree retard
750 ohm resistor = 6 degree retard (standard in a US car)
470 ohm resistor = 8 degree retard
220 ohm resistor = 10 degree retard
0 ohm resistor = 12 degree retard
 

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I think our 560's have more then that as sans resistor they all typically come up to 11-14 degrees IME over about 15-20 cars.

Jonathan
 

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Discussion Starter #20
Jonathan, Checked the timing at idle and found about 11 degrees. But, just for kicks I put a tank full of 87 in the old girl on a trip to the wine country this past weekend and noticed no difference at all. No detonation, no hard hot starts, nada...( being that is was cool and damp I'm not suprised) Not that I'm gonna do that again but I was just wondering what might result. I am still mulling this whole timing resistor thing around in my head but am enjoying much better performance and now I know my "carbon footprint" is smaller that it has ever been with the old girl. The older she gets the more comments we get on her. Had a couple comment on how nice our car was this weekend in Napa, where luxury cars abound. Funny, they drop 100K on a new luxo and it blends right in to the rest of the crowd, but our 18 year old antique turns heads like none of theirs. Guess it's just like a good piece of art, more appreciated as time goes by. What a car!
 
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