BenzBro

So i did a search on the subject of timing resistor, but didn’t find much detail for the M104 engine. Who knows about this minor modification that can be done? I've heard that it was put on the US models to compensate for Americans being cheap and using low octane. What do you guys know about this? Seems like a good modification if you run high octane.

bjay51d

I was gonna do that mod untill I realized I was one of those cheap americans...My car is not the best on gas asis Im not doing nothing thats gonna make it worst.Unless I run up on some turbo money .

bamberger_1

Hi BenzBro,
the resistor value is changing the ignition timing a little. It's not worth playing with it. If the gas qualitiy is varying you are fine with the factory setting. If you are swapping to premium only you can change the resistor setting towards "S" but the changes in fuel economy and performance are not convincing at all.

Eliot

Someone corresponded with (I believe) the Renntech engineers who said it wasn't about fuel grade. Instead the resistor is there to protect the catalyst and removing it could cause its early demise.

bjay51d

If that were true how come the european car wasnt fitted with it

bjay51d

I was just reading a thread on this resister on another site and someone actually said they were getting better gas milage.I might have to rethink things if I get better performance and gas milage.I might just give it a chance.How hard is it to get out, do I need tools? (sodering iron)or is it just plug and play?

Legoinsaniac

I've never done this, and I don't plan to, but this is what you want to read if you're interested. It's a loooooong thread on Mercedesshop:


http://www.mercedesshop.com/shopforu...ad.php?t=32224

bjay51d

If I had a 8cyl I wouldnt bother either

bamberger_1

The European models have those resistors too. The so called "EZL" which is a selector of resistor value in 6 steps. Maybe the US-models have a soild resistor and you need to swap it????

For the European style no tools are required to change the timing. Just pull the plug and turn it step by step. One step is 6 degrees of timing change (if I'm not mistaken, don't hold me accountable for that)

marco402

ok, took it out. located below brake resv, tie-wrapped to a/c hose.. markings just like pic. short drive showed no temp. diff., very slight improved throttle response at low - mid rpms, nothing noted at higher(+4000). it does seems to start better.....if thats the only improvement, it still might be worth it i'll finish this tank with it out, looking real closely at the temp gauge. initial opinion----performance increase so slight it's not worth it, but, the starting improvement is good, and if the mpg improves & NO temp increase I'll keep it out, otherwise I'll put it back....will report in a day or two, when tank is finished and I can judge MPG....

Kestas

Even if you're not one of those cheap Americans, and always fill with premium, this device is useful to protect you from unscrupulous gas stations who fill regular in their underground premium tanks. And even the honest owners may have a mixup during delivery.

marco402

while the cheats do exist, in Texas, the state conducts random testing, and when caught the fines wipe out a year of profits, and they are tested monthly for the next few years, so its really not worth it, and Chevron and Shell (probably the other majors too) yank the license from all the stations that the independant owns, so follow the tried and true formula...
1. buy from Major suppliers only, no Mom & Pop's, no Race-trac (that's spec.gas bought on spot market w/o any additives)
2. buy at HIGH-VOLUME stations, for fresh gas
3. if you can... but at company stations, due to strict testing and frequent tank sumping (less water/trash issues)
and 4. never buy when the tanker is there dumping a new load off, stir the junk up that settles at the bottom of the tank....
fortunately, there are many refineries here, so the distance from refiner, to distribution point, to station is shorter& the fuel is a bit fresher....(days old, not a few months!)

mgw_300e

The resistor does not exist on the m104 engine.

mgw_300e

What the resistor does is advance (or was it retard) the timing. You could get different ohm ratings for different timing. On the M103 engine it was good for a hp or two. The M104 uses variable valve timing.

marco402

confused? , valve timing and ignition timing are seperate things...while the ign. timing will advance +6deg from reference, it will still respond to knock sensor and pre-set timing curve. valve timing is adjusted through other means, and is usually just a overlap duration variable for torque enhancement.

mgw_300e

Sorry, I got confused at the end. The M104 has different ignition control than the M103, and as such it doesn't have the resistor that you guys are talking about.

It also has variable valve timing but that's got nothing to do with the ignition.

Kestas

Do the M103 engines lack knock sensors? This may explain why they have the timing resistor.

I don't see why a resistor would be needed if the engine (like the M104) has a knock sensor. After all, the function of the knock sensor is to set the timing on-the-fly to an optimal point just before knocking begins, depending on the gasoline (octane) running through the system.

bjay51d

I yanked mine out today and Im very happy with the results.No huge power gains,it just seem much smoother and doesnt seem to labor like it did.Wish I wouldve done it earlier.

BenzBro

Couldn't find the resistor on my 1990 300CE. I've heard that the computer senses type of fuel and makes the appropriate adjustment. Oh well, car is running great anyway.

I wish there was some definitive answer out there written in some reputable book or even a forum. Reading through the threads on this subject on mercedesshop, it seems like some see results, and others don't. No one really knows the best way to go. Hmm...

bjay51d

half tank gone with 150 mile on the clock this is a new fuggin record for my miracle whip.

jhodg5kc

MB literature states these Very conservative resistors were installed "in fear of poor fuel quality". And that running this resistor/timing map (it only effects timing below 2500 rpm) will cause decreased power and efficiency.

Ideally you want 10-12 degrees initial advance to get the most efficient burn.. These resistors set the timing around 3-4 degrees initial...ie, Far from ideal.

On all my CISE cars (103/117/116) I remove or fiddle w/ the R16 to get my 12 degrees initial..always helps down low

Jonathan

AMGDave

I pulled the resistor on my 300E (M103) and my fuel economy dropped a solid 10%. I put the resistor back in, and MPG went back to normal. There was no perceptible power gain with it removed.

My advice: Leave it alone. The placebo effect is hard at work here...

myfirstbenz

How have you found that 12 degrees is optimum? What ohm resistance is that? I believe I found more power w/out the resistor. Haven't calculated my mileage yet.

mgw_300e

Here is the info you need:

http://www.2phast.com/190E/default.htm

bjay51d

Numbers dont lie...Im over 20miles over what I usually wouldve had in just a half tank.THe resistor is history!