One idea...if you tape it, wrap it!

[Mario_Marques]

well, my car does not have one
cfg83, you can do the same thing about the "I use an HAI (hot-air-intake) :" without make your engine breath hot air(hot air is bad for the engine), you can put a resistor in the sensor or, i don't know how people call it in english, a variable resistor control(like the volume controller in the speakers, i think the name is potentiometer), do you get the idea?
We use the same system in performance to cheat the ecu and inject more fuel, you can do the same to inject less fuel.
In my country we call it evry-mod, you can build a manual control inside the car

[mcrews]

I just want to know where to put the hot dogs and where to put the buns.......

[cfg83]

Mario_Marques -

Originally Posted by Mario_Marques

well, my car does not have one
cfg83, you can do the same thing about the "I use an HAI (hot-air-intake) :" without make your engine breath hot air(hot air is bad for the engine), you can put a resistor in the sensor or, i don't know how people call it in english, a variable resistor control(like the volume controller in the speakers, i think the name is potentiometer), do you get the idea?
We use the same system in performance to cheat the ecu and inject more fuel, you can do the same to inject less fuel.
In my country we call it evry-mod, you can build a manual control insede the car

Quoting lots of my old posts :

Originally Posted by cfg83

...

Here is my take on the IAT-resistor-only mod :

1 - It "works" for performance WOT conditions because the ECU/PCM goes into open loop mode. Under open-loop mode, the ECU/PCM uses the IAT signal (as one of many input parameters) to determine fuel enrichment. The settings for performance will simulate CAI readings, aka lower input air temps.

2 - I claim it doesn't work under hypermiling driving conditions because the engine stays in closed-loop mode. In this situation, the IAT temperature reading to the ECU/PCM is ignored. As long as you don't stomp the accelerator pedal, it's not a factor.

On my Saturn, I have tested this with the ScanGauge by putting in different resistors and taking MPG readings over very short but multiple A-B-A test runs. The higher the "temperature spoof", the higher the MPG reading from the ScanGauge. However, the engine maintained exactly the same driveability.

...

The IAT may still contribute, but it should be a much less important factor under closed-loop conditions.

Tools like the scangauge, however will use the fake IAT sensor value in it's MPG algorithm, so it will *appear* to improve MPG :

Originally Posted by cfg83

...

I would be leery of using the SG to quantify the actual % gain. From what we (think we) know, the SG is using an algorithm to determine MPG, and the IAT is a significant parameter in that algorithm (see here). The ECU/PCM, however, is using the 02 sensor's Air/Fuel ratio to determine how much fuel to inject.

...

The "see here" is a simple test I did back in the summer of 2007 :

Originally Posted by cfg83

...

Yup, that's what I observed (garbage in, garbage out). ... time passes while I search through crap ... Ok, I found the numbers I took down when I did the test last year. This was on a very short and almost-flat 1.5 mile run that I kept "round-tripping". You can see that the South MPG is higher because that is the downslope. The conditions were very stable for every run. This was before my 5th gear swap, so my cruise control still worked. In my opinion, CC on the (almost) flat reduces "the human right foot influence" during ABA testing. (EDIT: The CC MPH was set at 30 MPH) Here are the numbers :

July 5th, 2007 around 1 PM with an outdoor air temperature of around 90 degrees F :

Run 1 
Resistor simulating 200 degrees F (as reported by Scangauge) :
56.1 MPG North
57.6 MPG South (electric fan came on)
57.5 MPG North
57.07 MPG Average

Run 2 
Resistor simulating 247 degrees F (as reported by Scangauge) :
65.3 MPG South
59.8 MPG North
65.3 MPG South
61.3 MPG North
62.93 MPG Average

Run 3
Restored to "normal" Hot Air Intake with real IAT, 132 degrees F average :
57.7 MPG South
51.3 MPG North
57.7 MPG South
53.4 MPG North
55.03 MPG Average

As you can see, the numbers jump right out at you. The car drove exactly the same. No hesitation at higher MPG.

...

Finally, here's a test by MetroMPG that didn't see any improvement :

Testing a warm air intake (WAI) - MetroMPG.com

CarloSW2

[Mario_Marques]

cfg83 my english is not good, it seems to me, in your teste, the trick it's not the iat but the real temperature?
Do you have any software to teste lambda values and ignition and injection timing?
It's possible to see what changes when you change iat value, because i think your ecu will pick other values to adjust mixture, maybe lambda value.
In my case my car uses maf value, water temp and fuel temp, for example, if i want to inject more fuel i will cheat the diesel temperature sensor(tell it that the fuel is very hot), so it will inject more(injection time will be bigger), but if my maf is reading to much air also teh quantity in that time will be big; crossed information in ecu.

[cfg83]

Mario_Marques -

Originally Posted by Mario_Marques

cfg83 my english is not good, it seems to me, in your teste, the trick it's not the iat but the real temperature?

Sorry. My english is messy. The first two runs use different resistors :

Run 1 = Resistor #1 => IAT @ 200 degrees F => 57.07 MPG
Run 2 = Resistor #2 => IAT @ 247 degrees F => 62.93 MPG

The last run is my HAI with normal IAT sensor :

Run 3 = normal IAT sensor => IAT @ 132 degrees F => 55.03 MPG

All MPG numbers are from the scangauge.

Do you have any software to teste lambda values and ignition and injection timing?
It's possible to see what changes when you change iat value, because i think your ecu will pick other values to adjust mixture, maybe lambda value.
In my case my car uses maf value, water temp and fuel temp, for example, if i want to inject more fuel i will cheat the diesel temperature sensor(tell it that the fuel is very hot), so it will inject more(injection time will be bigger), but if my maf is reading to much air also teh quantity in that time will be big; crossed information in ecu.

Hmmmm. I do not think all things that work for diesel work for gas. But you know more than me. I am saying what I have learned on these forums. I am not a heavy-duty car guy.

Also, I do not have software to test the lambda values. I can datalog all OBD-II parameters, so I can make a test where I save the IGN (ignition timing) value to see if it changes.

I definitely think the IAT resistor mod will work when the engine is cold, because that is when the ECU/PCM is in open-loop mode.

CarloSW2

[Mario_Marques]

Originally Posted by cfg83

Mario_Marques -



Sorry. My english is messy. The first two runs use different resistors :

Run 1 = Resistor #1 => IAT @ 200 degrees F => 57.07 MPG
Run 2 = Resistor #2 => IAT @ 247 degrees F => 62.93 MPG

The last run is my HAI with normal IAT sensor :

Run 3 = normal IAT sensor => IAT @ 132 degrees F => 55.03 MPG

All MPG numbers are from the scangauge.



Hmmmm. I do not think all things that work for diesel work for gas. But you know more than me. I am saying what I have learned on these forums. I am not a heavy-duty car guy.

Also, I do not have software to test the lambda values. I can datalog all OBD-II parameters, so I can make a test where I save the IGN (ignition timing) value to see if it changes.

I definitely think the IAT resistor mod will work when the engine is cold, because that is when the ECU/PCM is in open-loop mode.

CarloSW2

So, resuming, the trick is not the hot air right?
But sending "hot air information" to the ecu right?
So, you still could use cold air and trick the iat sensor, you could build a controller(potentiometer), in the interior of the car and controll the entire situation, if you do that, is better for your engine(cold air is healthier than hot air), and sttill have nice mpg
Yes, diesel is different, but the importante thing here is not the fuel but the engine management way of work(some cars are different, i have 5 cars and they all have different management even my diesel cars use different ways to calc the injection) that's why i ask you if you have some software to check the engine at realtime and see what changes, specially in this forum, your cars are quite different than european cars.

[Ang84Indy]

Originally Posted by Clev

Judging by the success people have with warm air intakes in improving mileage, I'm not sure I'd want to decrease underhood temperatures. Sure, it's harder on the battery, but otherwise I think it'd only help.

High underhood temperatures can destroy ignition coils, alternator diode packs, and any other electronic component that must dissipate its internally generated heat. It is good practice to lower underhood temperatures. As far as warm/hot intake air systems, using exhaust heat for this is a great way to lower underhood temperatures. You build a shroud around the exhaust and draw intake air from under the shroud as cfg83 has shown in his pic.

[cfg83]

Mario_Marques -

Originally Posted by Mario_Marques

So, resuming, the trick is not the hot air right?
But sending "hot air information" to the ecu right?
So, you still could use cold air and trick the iat sensor, you could build a controller(potentiometer), in the interior of the car and controll the entire situation, if you do that, is better for your engine(cold air is healthier than hot air), and sttill have nice mpg
....

No, there is no trick. I think the IAT resistor does not work for Ecomoding-style of driving. The resistor makes a fake IAT temperature. The scangauge has a formula that depends on a real IAT temperature. It calculates an MPG that is not real because the data is not real (GIGO). That is my theory. Here is a version of the formula that I think the scangauge uses :

Originally Posted by cfg83

Hello -

Ok, I now have a workable formula, thanks to post #9 :

Calculating MPG from VSS and MAF from OBD2 - MP3Car.com

That led me to this code :

//
// For signalling when one of the critical input variables has been received from the ECU/PCM
//
typedef struct
{    
    // 32 bits
    int    mph:1;
    int    map:1;
    int    iat:1;
    int    rpm:1;
    int   _PADDING:28;
} accessbits32;

//
// MPGData is global data structure for calculating MPG
//
typedef struct
{
    union
    {
        int          accessbit32:32;
        accessbits32 accessed;
    };

    double speed_kmh;
    double speed_mph;
    double map_inHg;
    double map_kPa;
    double rpm;
    double iat_c;
    double mpg_instant;
    double fuel_instant;
    double miles_instant;
    int    mpg_count;
    double mpg_avg;
    double imap;
    double maf_gs;
    double total_miles_travelled;
    double total_fuel_consumed;
} MPGData;

MPGData m; 

//
// Drivetrain specific variables that can be loaded from a file
//
typedef struct
{
    double ed;             // Engine Displacement
    double ve;             // Volumetric Efficiency
    double odo_correction; // odometer correction
} DriveTrain;

DriveTrain dt;

//
// calc_mpg_formula
//
int calc_mpg_formula()
{
    int ret;
    double iat_k; 
    int kmh_zero;

    iat_k = m.iat_c + 273.15;
    
    if ( iat_k == 0.0)
        iat_k = ALMOST_ZERO; 

    // IMAP =  RPM   * MAP:kPa    / IAT:K
    m.imap  = (m.rpm * m.map_kPa) / iat_k;

    // MAF = (IMAP/120)*(VE/100)*(ED)*(MM)/(R)
    // MAF   = ((   IMAP / 120  )*(VE:% /100)*(ED:liters)*(MM)   )/(R)
    m.maf_gs = (( m.imap / 120.0)*(dt.ve/100)*(dt.ed)    *(28.97))/(8.314);
    
    if ( m.maf_gs == 0.0)
        // then protect against divide by zero later on
        m.maf_gs = ALMOST_ZERO;
              
    // where manifold absolute pressure (MAP) is in kPa,
    // intake air temp (IAT) is in degrees Kelvin, 
    // R is 8.314 J/°K/mole and 
    // MM is the average molecular mass of air (MM) = 28.97 g/mole.
    // Note that, in the above formula, the volumetric 
    // efficiency of the (4-cycle!) engine is measured in 
    // percent and the engine displacement (ED) is in liters.
    
    if ( m.speed_kmh == 0.0)
    { // Not a good solution for 0 MPH, but lets give it a try
        m.speed_kmh = 0.161 / 1000.0;
        m.speed_mph = 0.10  / 1000.0;
        kmh_zero = 1;
    }
    else
    {
        kmh_zero = 0;
    }

    // miles travelled in 1 second
    m.miles_instant = m.speed_mph / 3600.0;
    
    if (( m.rpm < 100) && (kmh_zero == 1))
    { // then EOC
        m.mpg_instant = 9999.0;
        m.fuel_instant = 0.0;
    }
    else
    {
        // MPG - miles per gallon
        // 14.7 grams of air to 1 gram of gasoline - ideal air/fuel ratio
        // 6.17 pounds per gallon - density of gasoline
        // 454 grams per pound - conversion
        // VSS - vehicle speed in kilometers per hour
        // 0.621371 miles per hour/kilometers per hour - conversion
        // 3600 seconds per hour - conversion
        // MAF - mass air flow rate in 100 grams per second
        // 100 - to correct MAF to give grams per second => NOT NEEDED

        //MPG = (14.7*6.17*454*KPH*0.621371)/((3600*MAF)/100)
        //            => 710.7335739 * KPH          / MAF
        //            => 7.107335739 * KPH          / MAF_gs
        m.mpg_instant = (7.107335739 * m.speed_kmh) / m.maf_gs;

        // GPH / 3600 = GPSecond = ( MPH         / MPG          ) / 3600.0
        m.fuel_instant    = ( m.speed_mph / m.mpg_instant) / 3600.0;
    }

    m.mpg_count++;
    m.total_miles_travelled += m.miles_instant;
    m.total_fuel_consumed   += m.fuel_instant;

    if ( m.total_fuel_consumed != 0.0)
    { 
        m.mpg_avg = m.total_miles_travelled / m.total_fuel_consumed;
    }
    else
    {
        m.mpg_avg = 0.0;
    }

    ret = m.accessbit32;
    m.accessbit32 = 0;
    return (ret);
} // END calc_mpg_formula()

There are lots of limitations to what I am calculating. I need to get IAT, MAP, MPH, and RPM in one second in order to be able to datalog. This sounds like plenty of time for a computer, but my standing theory is that the ECU/PCM communicates in it's own good time.

Also, I don't know the Volumetric Efficiency (VE) of my engine. This doesn't address the knowledge that VE changes under different loads.

However, I *am* datalogging MPG numbers that are very very very similar to what a Scangauge displays. This has always been my goal, to have a formula that can give me the same *relative* MPG changes as the ScanGauge.

...

CarloSW2

[Mario_Marques]

"No, there is no trick. I think the IAT resistor does not work for Ecomoding-style of driving. The resistor makes a fake IAT temperature. The scangauge has a formula that depends on a real IAT temperature. It calculates an MPG that is not real because the data is not real (GIGO). That is my theory. Here is a version of the formula that I think the scangauge uses :

CarloSW2"

One question, your scangauge works independent from the car ecu?

"the scangauge has a formula that depends on a real IAT temperature."

If your car ecu manage the fuel mixture like the scangauge, could be real mpg values, it depends on how your ecu calc the air/fuel, i don't know how a aftermarket scan gauge work but i thing they probably use the same method as cars

[ShadeTreeMech]

I think everyone is missing something important in this discussion

Golf4 tdi "115" - '01 Golf TDI Sport Edition
Diesel

Thanks: 0
Thanked 0 Times in 0 Posts


I added the red for emphasis

a hot air intake on a diesel would be a bad idea since it could raise the exhaust gas temps too high. high EGTs is murder for a diesel.

HOWEVER a hot air intake on a gas engine can help reduce pumping losses by allowing a wider throttle opening. His car has no throttle, hence the confusion.

I know my Maxima has OEM wrapped tailpiping; I'm sure they also used some sort of a metal that resisted rusting, but either way, I have no issues with tailpipe leaks after 12 years of the car running and over 220K miles