Power Wire
#21
05-27-2009, 03:24 PM
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#22
05-27-2009, 07:27 PM
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Did a little testing myself. Lots of people probably know this already, but I think I know how this works:
1. The Stock temp sensor for the air intake is a variable thermister. At about 60 degrees F it reads 15K as it is heated it drops in resistance. (down to 2K with a little heat from my hear gun)
So:
2. The "power wire is a 4.7k resistor that wires in SERIES with the sensor which would basically ADD 4.7K resistance to whatever resistance the sensor is reading.
Therefore:
3. The added resistance makes the PCM think when its 60 degrees it would read 19.7K which translates to probably like 40 degrees.....
Is this correct or did I just make that all up?
If thats the case I assume people just cut one of the wires to the sensor and wire a resistor in line?
What would happen if you just removed the stock sensor and wired a 20K resistor across the two wires (parallel)
Wouldn't it think its always got 40 degree air?
1. The Stock temp sensor for the air intake is a variable thermister. At about 60 degrees F it reads 15K as it is heated it drops in resistance. (down to 2K with a little heat from my hear gun)
So:
2. The "power wire is a 4.7k resistor that wires in SERIES with the sensor which would basically ADD 4.7K resistance to whatever resistance the sensor is reading.
Therefore:
3. The added resistance makes the PCM think when its 60 degrees it would read 19.7K which translates to probably like 40 degrees.....
Is this correct or did I just make that all up?
If thats the case I assume people just cut one of the wires to the sensor and wire a resistor in line?
What would happen if you just removed the stock sensor and wired a 20K resistor across the two wires (parallel)
Wouldn't it think its always got 40 degree air?
#23
05-27-2009, 08:59 PM
#24
05-27-2009, 11:53 PM
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#25
05-28-2009, 12:10 AM
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#26
05-28-2009, 12:59 AM
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Correct, the PCM sends out a voltage signal, the IAT is a variable resistor that changes with temp. As the air temp heats, the resistance goes down, thus raising the return voltage closer to the original voltage sent out to the IAT (Usually 5V on most vehicles). All the resistor does is reduce the voltage going back to the PCM enough that when the PCM converts the return voltage signal into a temp. number, it is a bit lower due to the added resistance. The PCM, then adds a little timing because it thinks the incoming air is cooler.
If you already have a tuner, you may get too much advance with the resistor/power wire because the tuner has already advanced the timing and leaned out the fuel mixture. By adding more timing from the power wire, you may have detonation issues which is not a good thing.
If you already have a tuner, you may get too much advance with the resistor/power wire because the tuner has already advanced the timing and leaned out the fuel mixture. By adding more timing from the power wire, you may have detonation issues which is not a good thing.
#27
05-28-2009, 01:01 AM
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how much do you want anyway?
#29
05-28-2009, 08:15 AM
I'll shoot you a PM
Here is a pic of the one I made. Go to Radio Shack and buy a pack of 1/4 watt 4.7k resistors for $1. Get you some small gauge wire if you dont have any around the house and some heat shink and insulated male/female spade connectors.
On mine I folded over each end of the resistor in half and tinned them with soilder. I tinned each end of my wire (2 pieces of about 3in or so) and soildered them to each end of the resistor. I slid the heatshrink over it and ''shunk'' it. I then crimped two male spade connectors on each end and it was done. I went out to the truck and snipped one of the wires going to the AIT and crimped the female spades on each end of those wires and then connected the homemade powerwire in its place. You can reset the PCM if you want.
The only advantage to having a real PowerWire is that 1) you dont have to make it and 2) it is PnP meaning you dont have to cut one of the wires going to the AIT sensor. The downside it is cost $50 versus the $5 to make one.
On mine I folded over each end of the resistor in half and tinned them with soilder. I tinned each end of my wire (2 pieces of about 3in or so) and soildered them to each end of the resistor. I slid the heatshrink over it and ''shunk'' it. I then crimped two male spade connectors on each end and it was done. I went out to the truck and snipped one of the wires going to the AIT and crimped the female spades on each end of those wires and then connected the homemade powerwire in its place. You can reset the PCM if you want.
The only advantage to having a real PowerWire is that 1) you dont have to make it and 2) it is PnP meaning you dont have to cut one of the wires going to the AIT sensor. The downside it is cost $50 versus the $5 to make one.