Ok, so I have been reading a bit about the guys running Powerwires and seeing the threads about adding resistors in-line to the AIT to get lower temps and then hopeful better MPGs.

So I went to RS last week and bought a pack of 2.2k, 3.3k and 4.7k resistors. I took one out of each pack and made it into a PNP harness of sorts and took some readings and here is what I got. All readings were taken from my SC3815 with the truck at normal op temps at idle and in park with the hood fully up.

Without any resistor I was reading 89 degrees on the AIT.

With a resistor of 2.2k I read 78 degrees (a difference of 11 degrees)

With a resistor of 3.3k I read 73 degrees (a difference of 16 degrees)

With a resistor of 4.7k I read 67 degrees (a difference of 22 degrees)

So with those numbers it might be assumed that since 2.2k gives a difference of 11 degrees and 4.7k is 2x the amount of resistance of 2.2k and gives 2x the amount of temp difference (22 degrees) then a resistor double that of 4.7k might again give double the difference of temp readings of approx 44+/- degrees.

There are many threads over the lowers MPGs from a 90/10 Ethanol blend and I myself have been a long victem. In my 04 5.7 with the mods in my sig I got around 12mpg with a 90/10 blend. However, when I paid a very few cents more for a no-blend (100% gas) I instantly noticed I was averaging 14mpg. Keep in mind I have loud exhaust and I love to hear it which means I love to drive hard and fast.

But with all this being said and done, I filled up earlier today with 100% fuel (89 octane), put the 4.7k on the AIT and reset the PCM. I will let you guys know what MPG I end up with.

 

Keep us informed, I'm interested to know how well the 4.7k worked

 

Don't you need to make the pcm think it's hotter if you want more mpg? Colder air means more fuel will be thrown in the A/F mix so you will lose mpg. I had a power wire on my 3.7 which I think uses the 4.7k resistor and it did nothing for my mpg. Keep in mind that this was during the winter, and I have heard people say it works better in the summer. The temps I drove in ranged from 30F to 80F all with nearly identical mpg. I have taken it off and am currently testing to see if my mpg improves. I think this mod effects each engine and setup differently b/c many people love it and say it helped power and mpg, so let me know how it works for you.

 

Running lean will make a motor hotter.

Running fat will cool down a motor.

 

How does that effect mpg? Will a lean engine be more fuel efficient than a rich one?

 

A lean engine is more fuel efficient and more powerful.

Only problem is running TOO lean will do a lot of damage. I personally wouldn't mess with the mixture too much on a daily driver.

 

That was kind of my point. Since the resistors make it run rich it becomes less fuel efficient. The pcm keeps it dialed in unless your are running a tune like superchips or tricking the sensor, right?

 

Yes...but if you're not careful you can also cause serious damage from detonation. Running lean also gives a little more power. You can tell from the excess soot in the tailpipe that the factory tune is rich...I cleaned mine up before my tune and haven't had any come back in 6k miles.

 

Again do a search on the subject. He isnt gonna hurt a thing. I put a 10K variable resistor in my truck with an on and off switch and ran every test I could think of. It dosent make hardly any difference at all in hotter temps and dosent do anything in temps below 60 deg F. This wont hurt a thing If the air temp reading is too low the ECM throws out the info and compensates way before you can run the engine too lean and hurt things...

 

Funny you mention this part because when I did those readings yesterday and the outside temp was about 82*. The AIT was reading 89* and with a 4.7k I was reading 67*. Like I said before that was a difference of 22*. But this morning on my way to work it was 44* outside and with the 4.7k still on the AIT, the SC3815 was only reading 40* at idle and running running down the interstate at 60-70mph I was still only reading 40* on the SC3815. So the compensation you speak about makes sense with what happened this morning.