Well gang... I've been playing with theories and ideas for long enough now its time to put them into a design and see if it actually works. We all know the 24V's seem to take a good tumble in MPG's as the winter sets in well ISX proved that with the 12V engines with static timing that MPG's don't change. Well if you look at it the only thing that could be tossing this out the window is the IAT sensor on the 24V is changing the VP44 performance. Most know that colder air produces better HP/TQ because colder air is denser and requires more fuel to keep balanced. Well if you reverse this and warm the air (in theory) the VP44 should retune and burn according to the manifold temp. So what I've done tonight is fished through my resistor pile and found 3 I'm going to use for test candidates. Orange - White - Red - Gold = 3.9K Ohm = 116*F IATRed - Violet - Red - Gold = 2.7K ohm = 132*F IATRed - Black - Red - Gold = 2.0K ohm = 148*F IAT So now tomorrow I'm going to pull 3 test runs on the same piece of highway... Seeing if the highier the IAT temp increases the MPG or not... I'll can give you something to think about... Grid heaters are NOT controlled directly by the IAT... With the 2.7K Ohm resistor in place before even starting the grid heater still where hitting as normal. So there is more to the grid heater that the IAT temps... ... On the cutting edge again...

Unsafe Values - Don't Use! - Documenting values for tesing purpose!

163*F - 1.5K Ohms - Brown/Green/Red

173*F - 1.2K Ohms - Brown/Red/Red

184*F - 1.0K Ohms - Brown/Black/Red

unsafe how ..... Added a resistor and sitting at 144 ....

unsafe how ..... Added a resistor and sitting at 144 ....

Because 110-120*F will put you roughly at 140-150*F IAT. But since the engine was design to be run in weather above that I'm sure its either going to defuel or have some really wild settings for timing... Since no one is capable of seeing the timing table of the ECM lets say its safe to play inside the normal weather span but get above it well your pushing your luck...

lets say its safe to play inside the normal weather span but get above it well your pushing your luck...

makes sense

Used my fooler on a 100 mile round trip. The SG II AVG indicated a 1.3 mpg gain over previous trips to the same destination. The POT was set to 140* IAT on the SG II and the outside temps were 14*.Jim

I don't have scan gauges so I'm going with a fixed 2.2K resistor which I just soldered across the contacts on a DPDT switch. I've been through my wire assortment & not finding a nice 3 wire harness... so I guess I'll be picking some fresh wire up. (Amazing with all the wire I have around here... not what I want.) The extension harness shipped yesterday from Caspers. It's coming together.

Update... I beat my last few averages I'm now at 23.4... (91.6 Miles / 3.90 Gallons = 23.48 MPG) More on this later... Used 3.90 Gallons 91.6 Miles traveled Max Speed 58 MPH Average Speed 41 MPH As for fuel it was just below the quarter mark when I left the house... Take note of the last fuel entry... 2-14-11 http://forum.mopar1973man.com/attachment.php?attachmentid=2583&d=1298817223 ____________________________________________ Now I add a trip to Riggins, ID... I topped out at 25.3 MPG on the way to Riggins, ID but my way home bucking wind I still held 23.5 MPG... 23.5 MPG 120 Miles 5.08 Gallons Fuel logs...

Not to get off topic, but a good (cheap) place to buy anything electronic... www.mouser.com their in my backyard and I bought my resisters, delphi connectors and switches from them. You can buy directly from them and have them ship to you, or if your in the area and run it though a company, can pick up. Check them out.

I haven't performed this test mod (yet) but I did have an odd scenario this past weekend...I usually get about 275-290mi/tank (21-22gal) in town. I've only gotten a couple of true highway runs in the 24v, but the best had-calc'd MPG I've seen is about 18. This was a 250mi r/t at 68mph.Last saturday, I made a road trip to Williamsburg, VA.. Round trip was 368mi. I used just a hair over 1/2 tank for the trip. Overhead (although inaccurate) showed 21.6mpg @ ~68mph cruise control setting.I was shocked! And, I've got no programmers on the truck. It's bone stock, minus a bhaf and 5" exhaust.

Rogan, What does you overhead normally read? Have you tried to set it on ECO, and try and keep it above 20? Also, have you accounted for the larger tires in the mileage? You may be getting better than you thought.

Rogan, What does you overhead normally read? Have you tried to set it on ECO, and try and keep it above 20? Also, have you accounted for the larger tires in the mileage? You may be getting better than you thought.

I haven't had the larger tires on since November, actually. I've been running a 265-70-16 throughout the winter months, as the 295s (9.7% off of odometer) won't allow the use of my snow plow. The overhead AVG is usually around 13-14mpg (city) as city driving is my majority of travel. I haven't tried the ECO setting, and keeping it above 20 (yet) but I may try it out. I'm about to put a set of 235-85-16s on the truck, in the next couple of weeks. I know the odo will be skewed a little (4.1%). And I always hand-calculate.

Have you tried to set it on ECO, and try and keep it above 20? What is this you're talking about?

There is a setting in the overhead that gives instant MPG readouts.

I'm about to put a set of 235-85-16s on the truck, in the next couple of weeks. I know the odo will be skewed a little (4.1%). .

Keep us posted on that (pm me if u can after) as I am thinking of doing similar too see What it does to city mpg ;) !!!

I have found that my overhead is right on (I'll have to verify by hand calc. after I get my XZT+ installed). I've never found the instant readout to be useful... at least not how I drive when light. It swings up & down with every slight incline... so I guess it's working, but just not useful. There's a 2-3 second delay. You have to go down the road & if the road has an incline, you have to go up it. Well, I suppose you don't but I really resent those drivers who pull out & refuse to touch the GO pedal & force others to BRAKE to keep from hitting them. (Nothing wrong with a brief / moderate accelleration.)My "ave mpg" setting works very well & matches hand calculated mpg exactly. The interesting thing is that the overhead average will drop instantly on a cold start... after 10-20 miles it will be back up to previous average. If this reflects the "instant mpg" accurately, it must be very rich to suck the AVERAGE down 1-2/10ths. If the IAT fooler works as expected, throwing the IAT switch after a few minutes hopefully will lean the mix instantly. I have hilly terain in the run off my house, so not possible to test with the instant mpg setting. I am making the leap of faith that the cumulative of the instant readings = the ave mpg. I should receive the IAT extension cable today. I have my fixed 2.2k resistor soldered across the switch up position. Anxious to get to it.

Im with you, Russ. After yesterday's suggestion, I thought I'd watch the ECO selection this morning, on the way to work..

It IS useless. It fluctuates around so much, that it is impossible to even use as a guide. As an average, keeping it even remotely close to 20mpg, let alone above, is almost impossible.

[*]5th gear, 40mph, very light throttle on flat surface, it hovered in the neighborhood of ~15.

[*]4th gear, 30-35mph, was ~9mpg.

[*]2nd gear, 10mph crawl was ~20mpg.

m'kay...

Maybe I'll do a short video of my SGII and the setup I run...

[*]5th gear, 40mph, very light throttle on flat surface, it hovered in the neighborhood of ~15.

[*]4th gear, 30-35mph, was ~9mpg.

[*]2nd gear, 10mph crawl was ~20mpg.

m'kay...

You stock Rogan ? With timing advance my overhead will show 28-30 whilst cruising at 40-45 with od off ... And around 24-26 in overdrive at 65mph ....

I think those figures are around 2-3mpg high than real due to chip ...

I received my IAT extension marked Caspers Electronics #109017 "MAT Air Temp Senser Extension". The end fittings are exactly as you would expect of a professional item. The 2 individual conductors are fine wire... perhaps in the 20 gauge range. It's only a sensor harness but I guess I expected something heavier gauge. It wasn't cheap but the point is to have a solid weatherproof connection. I don't want to add resistance in my IAT fooler cable so I'll up size some. I'm not sure how much wire length I need... and extra slack in case it's needed. (The last time my dash came out the workers didn't release the zip ties on my accessories & yanked some of the wires out. IDIOTS! I'm thinking of putting the switch in the driver's knee panel. I want to be able to access it on start up.

Maybe I'll do a short video of my SGII and the setup I run...

I screwed up that video forgot to set the camera back to normal video not time lapse so it just a blur of numbers...:banghead:

I received my IAT extension marked Caspers Electronics #109017 "MAT Air Temp Senser Extension". The end fittings are exactly as you would expect of a professional item. The 2 individual conductors are fine wire... perhaps in the 20 gauge range. It's only a sensor harness but I guess I expected something heavier gauge. It wasn't cheap but the point is to have a solid weatherproof connection. I don't want to add resistance in my IAT fooler cable so I'll up size some. I'm not sure how much wire length I need... and extra slack in case it's needed. (The last time my dash came out the workers didn't release the zip ties on my accessories & yanked some of the wires out. IDIOTS! I'm thinking of putting the switch in the driver's knee panel. I want to be able to access it on start up.

The wires are 18ga in the extension. Same size as in the factory wiring harness.