Mario_Marques -
Quote:
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 :
Quote:
Originally Posted by cfg83
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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.
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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 :
Quote:
Originally Posted by cfg83
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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.
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The "see here" is a simple test I did back in the summer of 2007 :
Quote:
Originally Posted by cfg83
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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 :
Code:
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.
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Finally, here's a test by MetroMPG that didn't see any improvement :
Testing a warm air intake (WAI) - MetroMPG.com
CarloSW2