Power Wire
Hall Of Fame
Joined: Mar 2009
Posts: 19,168
Likes: 23
From: South GA
he's right about a resistor working in either direction and a VOM doesn't put out voltage when reading anything. Just go make yourself one and save the money. Now if you just really want to buy a Power Wire I will sell you one I have.
Banned
Joined: Nov 2008
Posts: 518
Likes: 0
From: Norfolk,Va
Not a zener diode...
Banned
Joined: Nov 2008
Posts: 518
Likes: 0
From: Norfolk,Va
A VOM does put out a calibrated voltage when set in the OHMS function...
Record Breaker
Joined: Jan 2007
Posts: 2,451
Likes: 0
From: CA
He's full of it...the resistor mod has been done on various vehicles since port injection was introduced and that's all the power wire is. Different value resistors adjust the IAT's signal in different ways...that's why they're telling you to use a 4.7k.
3rd gen Ram, Newbies
Joined: May 2008
Posts: 3,815
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From: Chicago
the resistor/powerwire is not doing the compensating, the ECM is. It thinks the air is a bit cooler then it is, so it compensates for what the temp is. now if the temperature outside gets hotter, the ECM picks up a hotter temperature and adjusts.
Site Moderator
Joined: May 2008
Posts: 9,657
Likes: 24
From: Louisville, Ky
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.
Hall Of Fame
Joined: Mar 2009
Posts: 19,168
Likes: 23
From: South GA
I gave all the numbers on what a 2.2, 3.3 and a 4.7k resistor does as far as making the PCM think the air temps are different. If I am not mistaken, the 4.7k was a bout a 44* difference while the 3.3k was 22* and the 2.2k was 11* cooler. All these numbers came out of a SC3815
