IAT and MAP sensor

[Ilikeoldfords]

Hahaha ok. I see now. Where would one purchase a rheostat like the one you have and which one do I need?

[Mopar1973Man]

Easier to pick out a resistor and stuff it in the plug. But remember this will disable the grid heaters. [TABLE][TR][TD=width: 50%, bgcolor: #3870cc, align: center]Temperature[/TD] [TD=width: 50%, bgcolor: #3870cc, align: center] Resistance[/TD] [/TR] [TR] [TD=width: 50%, align: center] 13°F[/TD] [TD=width: 50%, align: center] 56K ohms[/TD] [/TR] [TR] [TD=align: center] 26°F[/TD] [TD=align: center] 39K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 87ºF[/TD] [TD=width: 50%, align: center] 7.4K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 91°F[/TD] [TD=width: 50%, align: center] 6.8K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 100°F[/TD] [TD=width: 50%, align: center] 5.6k ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 107°F[/TD] [TD=width: 50%, align: center] 4.7K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 112°F[/TD] [TD=width: 50%, align: center] 4.3K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 119ºF[/TD] [TD=width: 50%, align: center] 3.6K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 123ºF[/TD] [TD=width: 50%, align: center] 3.3K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 127ºF[/TD] [TD=width: 50%, align: center] 3.0K ohms[/TD] [/TR] [TR] [TD=width: 50%, align: center] 132ºF[/TD] [TD=width: 50%, align: center] 2.7k ohms[/TD] [/TR] [TR] [TD=align: center] 143°F[/TD] [TD=align: center] 2.2k ohms[/TD] [/TR] [TR] [TD=align: center] 148°F[/TD] [TD=align: center] 2.0k ohms[/TD] [/TR] [TR] [TD=align: center] 163°F[/TD] [TD=align: center] 1.5k ohms[/TD] [/TR] [TR] [TD=align: center] 173°F[/TD] [TD=align: center] 1.2k ohms[/TD] [/TR] [TR] [TD=align: center] 184°F[/TD] [TD=align: center] 1.0k ohms[/TD][/TR][/TABLE]

[Ilikeoldfords]

Ok, now are all those temps created by different resistors? Which one should I get? I'm in central Washington so we have fairly cold winters.

[Mopar1973Man]

It not based on how cold your winters are. It based on what temperatures do you see in the summer time for IAT? So what your average summer temp +40*F would be a close guess to the size of resistor you want. Like myself I see 110-115*F in Riggins, ID quite often so 110 + 40 = 150*F. That would be my high mark temp. So typically IAT range 100-140*F for most people in the summer.

[Ilikeoldfords]

Aw I see. That makes more sense. I think the hottest we get is around 105.

[Ilikeoldfords]

So I would want like a 107* resistor because that would be my high mark?

[Ilikeoldfords]

I mean 140 would be about my high mark then. Did the math in my head but didn't type it lol. I'm curious and I would like to try this. Where would I get a resistor? Been a long time since I did anything with them.

[Mopar1973Man]

Aw I see. That makes more sense. I think the hottest we get is around 105.

So I would want like a 107* resistor because that would be my high mark?

I mean 140 would be about my high mark then. Did the math in my head but didn't type it lol. I'm curious and I would like to try this. Where would I get a resistor? Been a long time since I did anything with them.

Correct your high mark is outside plus 40 degrees so yes 140*F would be the highest you want. But you can play with 100-140*F and see what tinkles the truck fancy the most. Not all trucks and drivers are going to get optimal out of 140*F some might need lower. Remember this is rather still experimental being like mine works for my setup and driving habit but your driving habit and condition might be different.

[War Eagle]

"Correct your high mark is outside plus 40 degrees so yes 140*F would be the highest you want. But you can play with 100-140*F and see what tinkles the truck fancy the most. Not all trucks and drivers are going to get optimal out of 140*F some might need lower. "

[Ilikeoldfords]

All I'm doing is being experimental:) I like to try new things so thank you so much for all the help:) I'm very happy to be a part of this forum and work with everyone here. Thanks again

[hex0rz]

Wow, talk about one hijacked thread! :lol:Anyways, since I have a moment, I will tell you that O'reilly's had an IAT I used to compare mine to and even using a DMM on their sensor, it was still the same as mine. Could not get anything to read.. So, with my grid heaters working and the WTS light working, I will say my IAT sensor is good.I suppose I'm gonna have to further evaluate my situation in relation to my bad mpgs...I got 16mpg's last fill up. Was about a 50/50 city/highway driving. I'm getting about 300 miles to 1/2 a tank.

[Mopar1973Man]

Well since you can't get it with the DMM then use a live data tool and see what temperature your getting.

[hex0rz]

Well since you can't get it with the DMM then use a live data tool and see what temperature your getting.

I do not own any such electronics. Does an OBDII do that?

[Mopar1973Man]

I do not own any such electronics. Does an OBDII do that?

Some do and some don't. Like ScanGauge II and Ultra Gauge does. But standard OBDII reader most likely will not. Then there is other upper end OBDII readers like SnapOn, etc.

[hex0rz]

Some do and some don't. Like ScanGauge II and Ultra Gauge does. But standard OBDII reader most likely will not. Then there is other upper end OBDII readers like SnapOn, etc.

Ah, thats right... I know a guy with a Snapon live tool. I suppose he will be hearing from me soon.

[Ilikeoldfords]

Wow, talk about one hijacked thread! .

My apologies for hijacking.... On one more quick side note, I am experimenting with some resistors now. So far I have only tried a 2.2k ohm 1/4 watt. I havent noticed to much of a difference in mileage yet but we shall see. I also got some 3.3k ohm resistors too. I know I am not set up for mileage with my injector/turbo and tire situation but I figured it couldn't hurt to try. I am very intrigued to see if something might work. I average 17-18 usually and have been averaging 16.5 lately. maybe I can break 18 again??

[Ilikeoldfords]

So with the 2.2k ohm resistor, I am still only seeing about 16mpgs or so. I could only make about 300 miles to a half tank. I am also running the comp at 3x3. Next tank I will try running it with the comp off maybe?

[diesel4life]

Usually you will see slightly better mpg with a mild tune compared to stock because your timing is going to be more aggressive. Also things like driving in snow and excessive idle times in the winter could also be keeping your numbers down. Even say 10 or 15 minutes of idling time per day over the course of a tank of fuel is going to change mpg alot compared to summer time when u typically jump in and go.

[Ilikeoldfords]

I will have to keep that in mind. I have been driving in a lot of bad weather lately and I usually do let it idle for about 5 minutes or so before I go anywhere. This is usally about 3 or 4 times a day so that would make 20 minutes of just idling. I am still going to try turning the comp off and see what happens. I remember in the summer when I started to use it, I did have to try harder to keep my mpgs up for some reason. I only made like 15.5 mpgs on stage 5. Thats why I went down to stage 3. I was on sub-level 3 both times.

[Mopar1973Man]

Several other factor your fighting too.

-snip

100hp Sticks, Fass DDRP, Stock Turbo, 4.10's, 315/75/16 Dynapros

The overly large injectors are tough to gain MPG's with. Then the 4.10 gear with 315's tires. Lots of leverage load on the axles and requiring a lot of TQ to twist the axle from stop to full roll. For every 4 pounds of rotation mass you shave off you'll require 1 less HP to keep it rolling.

Then when you doing your MPG calcs are you using a GPS or the odometer with a percent offset? I found out the reason why the percent offset doesn't work. It because of the tire vs. wheels. Some people put wide wheels on and stretch the tire slightly bead to bead so now the profile is shorter giving you different profile then again you could be on a narrower rim and change it again there is a +/- about 1-2% offset to your offset calculate depending on the wheel size. So the only way to get correct odometer you need a GPS...