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#1
09-14-2007, 12:12 PM
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weak spark
Hi all,
I have a transistorized coil (blue) and I noticed the spark was yellow and did not make a snapping sound. I'm also getting about 12 MPG with my 72 250 M130 W114. I'm wondering if the coil is bad or the polarity is reveresed. There is a wire that's comming from the front driver headlight area to the negative coil. Is that correct? Thanks all.
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72 250 M130 W114 
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#2
09-14-2007, 07:11 PM
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Ok, Just put the multimeter on it, with the ignition on, engine not running, I'm getting 1.87V on the - side and 0 on the positive. That doesn't sound right so I flipped it.
Was that correct?
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72 250 M130 W114
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#3
09-14-2007, 08:40 PM
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Be careful. Some cars of this vintage run with the lead to the coil to +.
Also, I don't think a blue coil is right for the transistor ignition that you have. The blue coil is great if you go to a Pertronix setup, which seems to solve a lot of problems.
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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#4
09-15-2007, 12:04 AM
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Coil
The spec is 2.8 to 3.2 volts to the coil positive.
Sounds like you have a corroded connection to the 'Run' ballast resistor, a bad ballast resistor, or a bad Transisortized switching box. BTW, I have been connected to the the - coil side, with the positive side grounded to the chassis for 3 years. No problems. I read an article how Spark plugs require negative spark energy.
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1970 280S M130 engine- good runner 1971 250 M130 engine- #2 rod bearing, gone 1971 280SE (blown engine,parts car) 1977 German 280S W116-only 33 years old
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#5
09-15-2007, 12:48 AM
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Hey Munich,
Just to make sure I'm measuring right, I'm using the ground post from the battery to the positive post on the coil. Chuck, THanks for the advice, but I took her for a spin and OMG what power, she actualy peeled out of first and second. I AM SCHOKED!!!!!
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72 250 M130 W114
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#6
09-18-2007, 10:46 PM
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So, what did you do?
You gave us the result, without the 'method' that delivered the performance change.
With the normal set up, the voltage to the + coil is 2.8 to 3.2 volts, when the - coil is grounded. However, to tell you the truth, I never went back and measured the voltage to the - coil, after I made the reversal. Hmmmm...
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1970 280S M130 engine- good runner 1971 250 M130 engine- #2 rod bearing, gone 1971 280SE (blown engine,parts car) 1977 German 280S W116-only 33 years old Last edited by MunichTaxi; 09-18-2007 at 10:48 PM. Reason: spelling
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#7
09-18-2007, 11:37 PM
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That was it. I just flipped the wires for terminal 1 & 15 after I noticed the + had 0 volts and - had 1.8. Again, this is not measuring accross the coil, only from the ground post.
Is that where I should be measuring? Munich do you have a troubleshooting procedure? Thanks
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72 250 M130 W114
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Linear Mode
