Ignition Wiring Harness Improvement
01-30-05, 10:52 PM
#1
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Ignition Wiring Harness Improvement
from the scuderiaciriani "lightning" website....just curious if anyone has ever done this
Ignition Wiring Harness Improvement
The ECU on passenger side sends the firing trigger pulses to the igniter on the drivers side. This can't be changed and doesn't need changing.
The problem is with the wiring from the igniter to the coils. The coils are only about 2 feet from the igniter. But, the wiring goes from the igniter back inside the car to the main engine harness by the ECU, out the right firewall, to the engine where the solenoids are, across the front of the engine, then back on the left side of the engine to the coils. The 2 feet distance is now about 8 feet of wire carrying pulsating DC which can emit EMF if not properly shielded. This excess length also increases the possibility of the wiring being damage and/or misfiring.
While reinstalling my engine, I decided to go for the direct 2 foot route. The short ignition coil harness was removed from the main harness and the three coil connectors were cut off. These were then rewired with shielded wire to go directly to the igniter. The igniter output wires were cut and connected to the new harness. While doing this, the primary igniter wires were also connected to an extra male/female connector that allows them to run normally or be connected to my Crain HI6R.
Currently while breaking in the new engine, the Crane is disconnected and all are working fine. I did all of this to insure that the coils received the best possible signals and to increase reliability.
Ignition Wiring Harness Improvement
The ECU on passenger side sends the firing trigger pulses to the igniter on the drivers side. This can't be changed and doesn't need changing.
The problem is with the wiring from the igniter to the coils. The coils are only about 2 feet from the igniter. But, the wiring goes from the igniter back inside the car to the main engine harness by the ECU, out the right firewall, to the engine where the solenoids are, across the front of the engine, then back on the left side of the engine to the coils. The 2 feet distance is now about 8 feet of wire carrying pulsating DC which can emit EMF if not properly shielded. This excess length also increases the possibility of the wiring being damage and/or misfiring.
While reinstalling my engine, I decided to go for the direct 2 foot route. The short ignition coil harness was removed from the main harness and the three coil connectors were cut off. These were then rewired with shielded wire to go directly to the igniter. The igniter output wires were cut and connected to the new harness. While doing this, the primary igniter wires were also connected to an extra male/female connector that allows them to run normally or be connected to my Crain HI6R.
Currently while breaking in the new engine, the Crane is disconnected and all are working fine. I did all of this to insure that the coils received the best possible signals and to increase reliability.
01-31-05, 09:11 AM
#4
RX-7 Bad Ass
iTrader: (55)
It's hard to say what kind of advantage you'll get. I believe the signal wires are shielded, so they should be pretty resistant to electrical noise.
If you were TOTALLY re-doing the wiring, like on a full track car, I could understand redoing the wiring. In general, I just don't see if you'd get any advantage from doing this. There might be a small advantage, but I think you'd more likely have other problems from re-doing the harness - like faulty crimps or solder connections that show up WAY down the road and are near impossible to troubleshoot or find.
Dale
If you were TOTALLY re-doing the wiring, like on a full track car, I could understand redoing the wiring. In general, I just don't see if you'd get any advantage from doing this. There might be a small advantage, but I think you'd more likely have other problems from re-doing the harness - like faulty crimps or solder connections that show up WAY down the road and are near impossible to troubleshoot or find.
Dale
01-31-05, 10:40 AM
#5
Originally Posted by DaleClark
It's hard to say what kind of advantage you'll get. I believe the signal wires are shielded, so they should be pretty resistant to electrical noise.
If you were TOTALLY re-doing the wiring, like on a full track car, I could understand redoing the wiring. In general, I just don't see if you'd get any advantage from doing this. There might be a small advantage, but I think you'd more likely have other problems from re-doing the harness - like faulty crimps or solder connections that show up WAY down the road and are near impossible to troubleshoot or find.
Dale
If you were TOTALLY re-doing the wiring, like on a full track car, I could understand redoing the wiring. In general, I just don't see if you'd get any advantage from doing this. There might be a small advantage, but I think you'd more likely have other problems from re-doing the harness - like faulty crimps or solder connections that show up WAY down the road and are near impossible to troubleshoot or find.
Dale
I think the coil harness is $50 or so from Mazdaspeed Motorsports.
Jeff
01-31-05, 12:40 PM
#7
FYI: I beleive the stock harness also has some resistance wire in it (read current limiting).
Generally speaking, the longer wire will have more self inductance and that coupled with the capacity of the shield will act as a filter and result in a slightly longer rise time for the switching transition. I would expect that this would actually tend to reduce HF EMI potential somewhat.
Keep in mind that the engineers designing these things are aware of this and that these things are designed as integrated systems. So it is possible that they were after a particular result and it was effective to just loop the wire around. Since it adds cost, it is doubtful that they would have looped it around for entertainment. It is also possible that there was some sort of production restraint in producing the wiring.
Speaking as an engineer, the main point I want to make is that when things don't look right (and it's not as simple or low cost as it could be) then there's probably something else going on that is not obvious to us.
Generally speaking, the longer wire will have more self inductance and that coupled with the capacity of the shield will act as a filter and result in a slightly longer rise time for the switching transition. I would expect that this would actually tend to reduce HF EMI potential somewhat.
Keep in mind that the engineers designing these things are aware of this and that these things are designed as integrated systems. So it is possible that they were after a particular result and it was effective to just loop the wire around. Since it adds cost, it is doubtful that they would have looped it around for entertainment. It is also possible that there was some sort of production restraint in producing the wiring.
Speaking as an engineer, the main point I want to make is that when things don't look right (and it's not as simple or low cost as it could be) then there's probably something else going on that is not obvious to us.
