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#16
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when you fill up again after you have run regular with premium .. how does the computer detect this and advance the system?? |
#17
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Paul S. 2001 E430, Bourdeaux Red, Oyster interior. 79,200 miles. 1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron". |
#18
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Then it retards the timing in small increments until knock is gone. I.e., you cheap out on octane rating, you will end up with less timing advance & slightly less torque/hp/snap, balls, whatever you want to call it. The difference would be hard to notice for some people.
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2007 C 230 Sport. |
#19
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M103s don't have knock sensors, and will rattle, ditto for M117/M119 early with K-jet.
Play it safe, use premium. Detonation at high speed, when you cannot hear it, will roast the piston crowns and valves, not cheap. Peter
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1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs! |
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Right on psfred! I once purchased an off-lease vehicle that required premium unleaded, and shortly after owning it the check engine light came on. The car ran fine, but I brought it to the dealer to have it checked out and they discovered that one valve was dead and the others looked pretty lousy. The tech offered that the previous owner didn't use premium. Thankfully the work was covered under warranty, otherwise it would have been a $2,000 lesson on why you should pay the extra pennies at the pump. Of course, the lessee didn't care.
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2004 E320 Wagon 1989 300SE 1998 Range Rover 4.0 SE |
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I know this is heading off-topic, but if the
M103 has no knock sensor, what effect is there to removing the 'retard resistor'? Will it advance the timing beyond safe levels or just a little bit? Thanks, Bob
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Bob Roe Lehigh Valley PA USA 1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently 2007 Honda Odyssey Touring, 2014 E350 4matic |
#22
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The ignition timing/mixture program for the M103 is fairly complex, but I've heard that the resistor is there for certain modes, I think low speed low rpm high load or some such. removing it may cause knock (and may also get you some small amount of power at certain rpm).
I'd leave it alone, MB ain't gonna cheat you out of performance just to make the car slower (drive a C280 for proof). Peter
__________________
1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs! |
#23
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Yeah, I haven't been too tempted to unplug it. It's pretty well plastic-tied to a hose in an inacessible location, probably to preclude the casual tinkerer, like me.
Also I do notice a difference in throttle response with different fuel brands; my 300TE seems to be favoring Texaco premium, at least in this part of eastern Pennsylvania. Now I need to remember to carry Techron and/or the Progard Fuel System Cleaner with me when I might be refueling. |
#24
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2007 C 230 Sport. |
#25
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#26
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HFM fuel injection systems, like that on the 1993 and later M104 engines, are designed so that idle speed can't be adjusted. Idle speed is completely controlled electronically. This HFM injection system also has adaptive technology that compensates for conditions such as engine wear and unmeasured intake air and is designed to maintain driveability as the engine ages.
HFM-SFI can retard engine knocking to just the knocking cylinders, unlike EZL technology, which retards spark timing across the entire engine. This keeps the ignition timing point as advanced as possible for maximum power output.
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Paul S. 2001 E430, Bourdeaux Red, Oyster interior. 79,200 miles. 1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron". |
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