Another Spark Plug Question
MBWorld Fanatic!
Joined: Apr 2005
Posts: 3,784
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From: SCV SoCal
2002 CLK430
MarcusF,
Could you please explain something to be I'm a bit confused.
If our wires are resistor and the above spark plug is resistor, how does that effect performance?
Would I be able to buy non resistor wires and run the opposite set up (opposite from OEM). And if I did this would I be able to tell the difference?
Thanks man!
Could you please explain something to be I'm a bit confused.
If our wires are resistor and the above spark plug is resistor, how does that effect performance?
Would I be able to buy non resistor wires and run the opposite set up (opposite from OEM). And if I did this would I be able to tell the difference?
Thanks man!
A slightly longer answer begs the question – “How can you avoid impedance mismatches?”
Answer: By using plugs and wires that were designed for your car (the plug or wire manufacturer doesn’t matter in this equation, just the total amount of resistance).
An unreasonably long answer will cause us to back up a bit.
A resistor plug literally has a resistor “in” the plug. Without it, when the spark jumps from the center electrode to the ground electrode the energy causes a specific high frequency noise. That noise is EMI (electromagnetic interference), which can result in RFI (radio frequency interference). There is a difference in these two types of interference, but they both “interfere”. EMI is when an electromagnetic emission/discharge results in an electrical or electronic disturbance. RFI is when an electrical disturbance impacts a specific frequency range. Either can disrupt an ECU. Ever hear of a military operation where a signal is jammed? They’re talking about the same thing – RFI/EMI. Another example of RFI/EMI is when in the old days cars and/or bikes without resistors would mess up a TV signal to the point where the picture would literally flip upside down (ask your grandparents – this was common in the 50’s).
Now you understand the racket that occurs when the spark jumps is why there are resistor plugs and you’re thinking “why do I need resistor wires?” You need them because non-resistor wires use a solid core and produce a lot of RFI. Automobile engines use resistor wires so as not to drive their own ECUs bananas. Not driving the “nav system with satellite radio, Bluetooth attached cell phone, and capable of iPod streaming” bananas is a side benefit. So no, you probably don't want to use non-resistor wires.
Thankfully we don't use resistor caps, or there would be another thing to consider.
The main purpose of an ignition system is to ignite all the fuel. The M113 has a dual plug ignition system. This is VERY efficient and early Porsche owners pay BIG money for this conversion. I may be wrong, but I have doubts that reducing the amount of resistance in properly matched plugs and wires will result in any additional fuel being burned in a dual plug system.
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Joined: Jul 2005
Posts: 1,224
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From: S.E. FLA.
05 ML-500 , 03 CLK5.5 AMG has left the Garage
Resistor Plugs
Marcus. Is spot on . Here is some info you may not Know. The resistor in the S/P is around 5000 ohms. the Suppressor type S/P is 500 ohms. The wire length is so short on MB M-113/ 112 motors , there resistance is not that effective . I believe that the switch from Suppressor to Resistor tells the story. Impedence is not an issue at the voltage level. Maybe important around low voltage sound equipment.
In the old days Some V-8s had 3' to 4 ' length of spark plug wire from the Distributors to the Spark plug. Lots of EMI & RFI. Early Transistor ignitions & fuel injection system needed all the suppression they could get.
The main issue with oem S/P wires is the harsh ? Hostile environment they are subject too. The relief Entry to the S/P threads in the cyl head , traps moisture & water. Short runs around town does not build enough heat to boil the water into a vapor. Over time hot & cold cycles crushes the S/P sealing washer , it partially loses it sealing ability .Letting water wick into the Threads. I apply some Wurth CU-1100 Anti-Corrosion paste on the last 3 treads near the sealing washer. This stuff is good to 2000 * F.
Also the steel cover on the OEM wires , at the S/P connector , Lays in the water at the S/P Relief entry on the Cyl head and corrodes badly . And develops a current path for the High voltage , to bypass the S/P. Can you find the misfire?? Now.
Unfortunately it is run too long in the shorting out state & Damages the Ign Coil pack. Moral of the story Here , dont wait to 50,000 or even 100.000 mile. Not all enviromental conditions are the same.
We can talk about Iridium coatings & Platinum pads If Needed
Cheers _PTEngineering
In the old days Some V-8s had 3' to 4 ' length of spark plug wire from the Distributors to the Spark plug. Lots of EMI & RFI. Early Transistor ignitions & fuel injection system needed all the suppression they could get.
The main issue with oem S/P wires is the harsh ? Hostile environment they are subject too. The relief Entry to the S/P threads in the cyl head , traps moisture & water. Short runs around town does not build enough heat to boil the water into a vapor. Over time hot & cold cycles crushes the S/P sealing washer , it partially loses it sealing ability .Letting water wick into the Threads. I apply some Wurth CU-1100 Anti-Corrosion paste on the last 3 treads near the sealing washer. This stuff is good to 2000 * F.
Also the steel cover on the OEM wires , at the S/P connector , Lays in the water at the S/P Relief entry on the Cyl head and corrodes badly . And develops a current path for the High voltage , to bypass the S/P. Can you find the misfire?? Now.
Unfortunately it is run too long in the shorting out state & Damages the Ign Coil pack. Moral of the story Here , dont wait to 50,000 or even 100.000 mile. Not all enviromental conditions are the same.
We can talk about Iridium coatings & Platinum pads If Needed
Cheers _PTEngineering
Last edited by PTE; Dec 8, 2011 at 09:47 AM.
