[Diy_efi] Poor earth toasting ECU?

Fri Jun 28 15:47:53 GMT 2002

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An intermittent Earth, or ground, would reverse bias many inputs. That isn't 
nice, but probably anticipated by the designers. If it still works, its 
probably OK. Many have suspected plug wires of causing intermittent misfires. 
I like solid plug wires with shielded resistor plugs and rotor (Like Mercedes 
and others) Low resistance wire approximately doubles the energy delivered to 
the spark plug and makes the spark duration longer. Physically locating a 
small resistance close to the arc at the plug tip (built in to resistor 
plugs) and rotor and shielding them reduces RFI. The lower voltage gradient 
across the wires also reduces crosstalk. I've measured the voltage required 
to fire a spark plug, it's about 2 kV cruising and 3 kV under load with a 
minimum energy requirement of about 20-40 mW/sec (A GM HEI stores about 140 
mW/Sec/Spark and delivers about half of that up to about 4500 RPM.)
Jim

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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">An intermittent Earth, or ground, would reverse bias many inputs. That isn't nice, but probably anticipated by the designers. If it still works, its probably OK. Many have suspected plug wires of causing intermittent misfires. I like solid plug wires with shielded resistor plugs and rotor (Like Mercedes and others) Low resistance wire approximately doubles the energy delivered to the spark plug and makes the spark duration longer. Physically locating a small resistance close to the arc at the plug tip (built in to resistor plugs) and rotor and shielding them reduces RFI. The lower voltage gradient across the wires also reduces crosstalk. I've measured the voltage required to fire a spark plug, it's about 2 kV cruising and 3 kV under load with a minimum energy requirement of about 20-40 mW/sec (A GM HEI stores about 140 mW/Sec/Spark and delivers about half of that up to about 4500 RPM.)<BR>
Jim</FONT></HTML>

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