MPG fooler - Design phase

[SASQCH]

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.

[Mopar1973Man]

Like on my High idle kit when I was building them I made the length about 6 foot so it gave plenty of length for hiding and tucking wires out of the way. 18 AWG is fine...

[flagmanruss]

Do I need to determine polarity of each lead in the extension harness? Both wires are black. Or is there a way to tell from the plug orientation? I don't have the truck here right now to go check. I'm thinking since resistors are not, that the (variable resisitor) OEM sensor would not be either... but I don't want to @SS UM E anything.I would like to have this ready when the truck comes back from the shop.

[ISX]

Do I need to determine polarity of each lead in the extension harness? Both wires are black. Or is there a way to tell from the plug orientation? I don't have the truck here right now to go check. I'm thinking since resistors are not, that the (variable resisitor) OEM sensor would not be either... but I don't want to ___ UM E anything. I would like to have this ready when the truck comes back from the shop.

Nope, a resistor "swings both ways" As long as it has one wire going to it and another wire going out, it will work.

[Mopar1973Man]

No polarity...

But for your information Black/Light Blue is GROUND

And Black/Red is the +5 Volt signal from ECM.

Just no OPEN or SHORTS allowed!

[flagmanruss]

NOPE, the wires in the IAT extension harness is not color coded... just 2 black wires.

--- Update to the previous post...

Anybody help me out here? (I guess I'm being OCD about this.) Orientating according to the locking tab, which wire is +?

Thanks,

Russ

[ISX]

NOPE, the wires in the IAT extension harness is not color coded... just 2 black wires.

--- Update to the previous post...

Anybody help me out here? (I guess I'm being OCD about this.) Orientating according to the locking tab, which wire is +?

Thanks,

Russ

Here you go Russ, went out and took a pic.

[flagmanruss]

Thanks, ISX,

One picture is worth a thousand words... Now I know which wire to cut!

Russ

--- Update to the previous post...

"snip"

Documenting for those who come after: I note that the connector is marked "A" & "B" leads in your really great photo. My aftermarket piece also has the A B marking although it is good light & reading glasses fine. The B lead is + so that is what I cut.

Warming up the soldering iron now.

Thanks again,

Russ

[stodg73]

Rogan, Have you tried to set it on ECO, and try and keep it above 20?

When I posted this question, I was trying to see what you could do for MPG's. I realize that this is hard to do, also I know from experience that keeping it above 20 is extremely hard, especially with the changing terrain, road conditions, etc. For a while, I thought that keeping the engine RPM low that I was getting the best MPG, on this I was WRONG. I found that keeping the RPM up around 1900-2100, that I was getting better MPG's by using the ECO setting on the overhead. Now, I realize that every truck is different, and they all get different MPG's, you just have to find the best RPM/gear that your engine/trans delivers. Since I have been using the overhead, I have changed my driving habits to get better MPG's. For the longest time, when I was driving on the Interstate, I would generally turn off the ECO mode, because I don't want to be upset about how low the instant MPG's were. Now, I leave it on to see how my MPG's are doing. Where I am, the speed limits are 75 MPH on the Interstate, 65 and below on the secondary highways. Now, when using the IAT Fooler, I get even better MPG's. Even though the increase has been about 2 MPG's. So over the course of a tank of fuel I am only going 60 miles further, so it is a little better. All I am doing is turning the fooler on.

[volkswagon]

[quote=

For a while, I thought that keeping the engine RPM low that I was getting the best MPG, on this I was WRONG. I found that keeping the RPM up around 1900-2100, that I was getting better MPG's by using the ECO setting on the overhead. Now, I realize that every truck is different, and they all get different MPG's, you just have to find the best RPM/gear that your engine/trans delivers.

QUOTE]

Interesting point as I was the same way, always running low rpm til I got my Scangauge. Now I run in the 1900-2100 range as well. I haven't had a chance to run much for testing with my IAT fooler but observing the Scangauge I'd say for me it doesn't do anything. I guess I just have one of those 'different trucks'.

[flagmanruss]

When trying to get mpgs, I prefer to NOT use the Cruise Control. As I top a hill, I try to watch the crest & feather the throttle to anticipate the power needed. It can be tiring on a long trip but I can see a couple of tenths difference immediately. I use the cruise for short periods, like when I need to rest or want to shift position without loosing my speed...

Realizing every rig is different, terain is different, loads are different... logically, I expect the IAT fooler to only bring the mpgs back to summer mpgs. That ought to be a couple of mpgs for me.

I don't put a lot of miles on since the CTD is not my Daily Driver... If the mpgs were better it sure would be... I can't wait to get it back & install the IAT fooler.

--- Update to the previous post...

Just a thought... I was thinking about the IAT fooler only having cool weather benifits. That might not be the case. In warmer weather, every cold start... the IAT is lower (not as low as that cold hunk of iron outside but still lower). The IAT fooler speed the switch over even in summer... I don't know if would be measurable... a smaller differential. Still I'll take anything I can get.

[AH64ID]

logically, I expect the IAT fooler to only bring the mpgs back to summer mpgs. That ought to be a couple of mpgs for me.

I would be surprised if you got back to summer economy. The biggest hit from winter driving is the cold air and its effects on tires, gear lube, air density, etc... You will gain some back, but it still takes more hp to do 65 in 0* weather than in 75* weather.

[flagmanruss]

AH64ID, You make a good point. Cold lubes & winter slippage will always be a winter season limitation, not just the engine function. Faster switch over to warmed up settings can only do so much. While equalling summer effiency is a great goal, will probably be impossible to achieve. It will be interesting to see how close we can come... this time next year, we should have data.

[balsip]

How about using a relay that keeps the IAT in the circuit by default when starting and then a momentary push button that latches the relay on and switches in the resistor of say 4.7 K. or so?Relay only de-energizes when ignition is turned off.

[SASQCH]

How about using a relay that keeps the IAT in the circuit by default when starting and then a momentary push button that latches the relay on and switches in the resistor of say 4.7 K. or so? Relay only de-energizes when ignition is turned off. [ATTACH=CONFIG]2622[/ATTACH]

Yup, that should work, you are just limited to the resister setting whereas the pot allows some adjustment.

[flagmanruss]

I think the 4.7 resistor or full scale on a 5 ohm pot is too high. It may even cause problems like over-heat defueling (possibly). I used the fixed 2.2 resistor which seems to be most reasonable. To use a pot, one needs a scan guage or equiv to adjust.The relay is an interesting concept.

[Rogan]

funny, i was looking at the schematic, and totally understood everything, then i saw the notes/legend. LOLI've been in electronics too long..

[Mopar1973Man]

I like the relay idea... just I know I got to get down to Boise, ID to find anything like that though... :banghead:

[Prowelder]

Well after reading this, I think I'm going to build an add on switch for my current High Idle System. Looks like a good deal, just too bad I'll have to wait to test it out b/c my tranny is broken!:doh:So do you feel the 2K is best Mike or the 2.2?

[Mopar1973Man]

Well after reading this, I think I'm going to build an add on switch for my current High Idle System. Looks like a good deal, just too bad I'll have to wait to test it out b/c my tranny is broken!

So do you feel the 2K is best Mike or the 2.2?

That's why I'm asking as many people to try this mod out and see... I'm wondering if the 2.2K ohm does good for everyone or maybe a different climate requires something else... I don't know...

But I would say any value that you would normally see during your high MPG numbers would be a good place to start...