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...

I pulled my IAT wire a while back when I was testing it and the grids were normal before starting, but then you would start it and the light would just blink. I think that's how it was anyways. Test it out some more, there has to be something as to why it does it in the drivethru in the winter when I turn it off for a sec, it goes through the post start crap again, but I don't think it does it in the summer, so it measures SOME sensor.

I wonder if it is ECT on prestart and IAT on post start.. Hit both foolers

Well there is 3 temperature sensors on these trucks...

[*]ECT (Engine Coolant Temperature) Sensor

[*]IAT (Intake Air Temperature) Sensor

[*]Battery Temperature Sensor (Under the driver side battery)

I wonder if the ECM uses input from all 3 or combination of the above to figure out the grid heaters... But at any rate I'm going to see if I can fool the ECM to thinking its a summer day and get the MPG's to rise I hope...

Lets see in the morning...

I doubt the battery ties into anything. I ripped mine out long ago and as much as every tiny little thing gets to me I would have noticed it. If the crack on my windshield moves a 1/4" overnight I will notice it :lmao:Hmm, my ECT is busted though and the grids still work as they should I bet it's not the same on the 12V's so yours might use all 3 sensors for all I know. This test will be interesting.

Hmmm... That might not be a bad idea... I think I'm going to push it a bit harder... I'm thinking it might be a killer idea of fooling the ECT at a higher temp say 205*F and lock it down and see if that changes the factors of MPG's ... Also see if that effect the grid heaters at startup... Oh... All the neat stuff I can fool the ECM into doing... (Evil laughter)

DKnaks over on MidwestDC built an adjustable potentiometer style resistor IIRC to do just this and mounted it in with his high idle kit to play with iat reading to do what you are trying but I can't remember his results right off.

Yeah I remember that but never heard much about it...

I'm all ears on this one:hyper:

subscribed. What are your baseline ambient and IAT temps to compare ??? Are you using the scanguageII to do this ?More details on the test and instruments plz sir MM So one more question - I thought part of the purpuse was engine protection - kinda to prevent overfueling before the engine was warmed up - any bad side effects to this ??

subscribed. What are your baseline ambient and IAT temps to compare ??? Are you using the scanguageII to do this ? More details on the test and instruments plz sir MM So one more question - I thought part of the purpuse was engine protection - kinda to prevent overfueling before the engine was warmed up - any bad side effects to this ??

Mike says it is all for emissions.. Good for the DOT bad for the MPG's It won't do anything but make the timing whatever it was in the summer. Mine's the same all year and I never notice anything so I don't see any reason why a 24V would have any issues, other than more mpg's. I came up with the theory after seeing over and over that Mike said when he hit 100F IAT, his mileage shot up. Now when everything is warmed up, the ECT is the same on both our trucks, the boost is the same, everything is the same when they are warmed up. After driving to Nebraska and back getting the same mileage at 25F (no winter front) as I do in the summer, I knew something was going on with the 24V's. I have got the same mileage all year since I have owned the truck. The more you think about it you come to the conclusion that the IAT is the only thing different between winter and summer. It would be one thing if I saw a mileage drop as well, but something is wrong when he can hit 100F IAT and have his mileage increase. Thing is, it has to be 50F+ to hit that, so I think by fooling it he can get his mileage back in the winter, since that is essentially what my truck does, fools it all year long.

this is gunna be nice.

This makes a huge amount of sense. I often leave the MPG Average display up. Since I'm stock, the overhead is accurate. Even on the same trip a big difference is noted between warmed up VS cold start. I know not all agree, but I believe the cold front helps bring IAT up. Anything that improves MPG will be very welcome indeed. If this works, it will be revolutionary. I want one!!

This makes a huge amount of sense. I often leave the MPG Average display up. Since I'm stock, the overhead is accurate. Even on the same trip a big difference is noted between warmed up VS cold start. I know not all agree, but I believe the cold front helps bring IAT up. Anything that improves MPG will be very welcome indeed. If this works, it will be revolutionary. I want one!!

I have no proof on the winter front and IAT... But I did use an IR temp thing on the driver and passenger side of the intercooler and did see a big difference (like 20F). So I am convinced it DOES do a little for IAT's. I am just not certain if warming them up is a good thing, I mean I got the same mileage without them at 25F.. I think the colder air adds power based on seat of pants (so I could be wrong there). The 12V doesn't care what the IAT is and since it feels like there is more power I think the front doesn't need to be there. The only reason it is there is for the 24V's to get their IAT temp up and get into the mileage tuning of things. So fool it and take the front off and you will have your mileage back and have more power. Mike told me before the engine warms up it advances timing a LOT. When it gets up to operating temp is when it starts to level out on mileage. Cold engines are not going to be efficient no matter what, and that is not what I am trying to fix. What I am trying to help you guys with is in the winter when the IAT's never get above that "mpg threshold", you drop 2mpg or so from the summer mileage. If you can make the engine "think" it is warm, it should bump the mileage back up. Sounds like it would be inefficient if it is fooled like that but mine is the same setting all year and obviously retains the same high efficiency all year long.

Subscribing to this. If the charge air is going into the intercooler at 55* and coming out at 35* and the IAT sees this as too low, it dumps more fuel in, per the ECM? If you change/fool the IAT into thinking that the charge air is 75* instead of 35* then this is where the ECM is getting into the mileage settings? The end results will be interesting.

Actually like today the temps are starting at 30*F now... So in theory the IAT temp for today will be ~70*F IAT which is short from my crossing point of 100*F IAT. Remember its a rough +40*F offset. So I got my resistors picked out to fool to 116*F, 132*F, and 148*F... Make the engine think its summer...

Subscribing to this. If the charge air is going into the intercooler at 55* and coming out at 35* and the IAT sees this as too low, it dumps more fuel in, per the ECM? If you change/fool the IAT into thinking that the charge air is 75* instead of 35* then this is where the ECM is getting into the mileage settings? The end results will be interesting.

Actually its based on the simple principal that if the air is colder it more dense so to keep the air fuel balanced it need more fuel. So in reverse respects if the air temp is warmer and less dense then less fuel is required to keep balance. But since the older mechancial VE and P7100 pump could careless of the air temp then why not fool it to a good temp for MPG numbers?

Actually its based on the simple principal that if the air is colder it more dense so to keep the air fuel balanced it need more fuel. So in reverse respects if the air temp is warmer and less dense then less fuel is required to keep balance. But since the older mechancial VE and P7100 pump could careless of the air temp then why not fool it to a good temp for MPG numbers?

That is the part I don't get. I believe the cold air being more dense means the fuel is injected and able to ignite better since there is more air molecules in there to feed the fire. I think it runs leaner in the winter than summer because of this. It also explains why it seemingly has more power. I really think it makes it more efficient. I only think this because there is the drop in BTU content in the winter fuel, so how would I remain at the same mpg?, making me think it is making up for the loss in BTU by burning more efficiently.

I know all my turbo cars in the past, with MBCs, I've had to dial the boost back a little, to avoid the overboost spiking where I'd often see boost increases of 5-10psi in the cold air.The air, as stated, is much more dense, so the molecules are closer together. This allows the turbo to force many more air molecules into the combustion chamber. This doesn't increase the volume, obviously, only the molecular count within the same given space.Add more air to a fire and what happens? It gets more intense. More intensity in the same confined space equals a greater (albeit leaner) burn.All electronic fuel-controlled cars run 'fatter' when cold, burning more fuel.

Well some basic testing done... Now as for the grid heater its based on both the ECT and IAT temps for a trigger so if I use my ECT fooler from the high idle and the 2.7K ohm resistor in the IAT sensor fooling to 132*F the grid heater are not present at all... As such the truck starts and run similar to a 12V the idle is a bit low and rough for a second or two. Then it will idle normally... (Interresting! ) Ok... Now as for the test run I left the house with the 2.7K ohm resistor in place and could see a instant change in the behavor of the truck. The MPGs was notably high just during the warm up period. So I drove till the engine coolant was at full temp of 195*F before I started testing... The first batch of test I threw out because it was to short of a distance to measure and had a slight down slope which skewed the numbers. So I found another spot that was a bit flater and desided to run both directions and test it out. This gave me roughly 4 miles round trip going point A -> point B -> point A again. So what I used was the ScanGauge II reset the current MPG number to ZERO each test and tried to drive the same way both times using cruise control both ways set at 55 MPH. Here is some of the data pulled for 2 miles out and 2 miles back to start point... FIA = Intake Air Temperature.FWT = Coolant Temperature.CMG = Current MPG for this Test.MPG = Instant MPG of the moment. Resistor fixed 13*F (14.7 MPG's) Resistor Fixed 132*F (15.5 MPG's) Now this isn't actual MPG numbers. These are short based number that reset each time so the SGII never has a real chance to average out to a full MPG number but I'm going to start doing some long term testing now and see who it performs...

ADDON INFO: Doing a little math for the to test runs... (2 miles out 2 miles back) 55 MPH / 14.7 MPG = 3.74 GPH 55 MPH / 15.5 MPG = 3.54 GPH So this goes to prove so far that cold air intake and such don't do anything for MPG number they will do something for HP/TQ numbers. Another tidbit that I found interesting while playing around was the truck was capable of building a full head of boost at 35 PSI with the 132*F IAT than with the 13*F IAT it only pulled 31 barely 32 PSI...

ADDON INFO: Doing a little math for the to test runs... (2 miles out 2 miles back) 55 MPH / 14.7 MPG = 3.74 GPH 55 MPH / 15.5 MPG = 3.54 GPH So this goes to prove so far that cold air intake and such don't do anything for MPG number they will do something for HP/TQ numbers. Another tidbit that I found interesting while playing around was the truck was capable of building a full head of boost at 35 PSI with the 132*F IAT than with the 13*F IAT it only pulled 31 barely 32 PSI...

Well some basic testing done... Now as for the grid heater its based on both the ECT and IAT temps for a trigger so if I use my ECT fooler from the high idle and the 2.7K ohm resistor in the IAT sensor fooling to 132*F the grid heater are not present at all... As such the truck starts and run similar to a 12V the idle is a bit low and rough for a second or two. Then it will idle normally... (Interresting! )

I find that part interesting and makes me think some more.. If yours run off of ECT and IAT for the grids, I am wondering if the ECT also ties into the mix with the timing. It would only matter during warm up and you would have to just instantly fool it into thinking it was 195F and see if the warm up mpg's went up even more. But I think this is kinda a waste of time to try and go that far just for warmup so I wouldn't bother, but I am betting it ties into it a little. If you are getting in it and going so the engine is 30F also, you could flip that 123F switch for a while and see if it does anything Now the boost thing is something else that is incredibly interesting and gives more clues. I gotta do some more searching and reading and figure out exactly what that pump does with timing if it is cold/hot IAT's. I *think* whatever it does with high IAT's is not supposed to raise boost like that, but because you fooled it, the ACTUAL cold intake air has the effect of producing more boost.