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Matt
Dodge Dakota
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11/14/2003
17:57:46
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 Subject: New IAT sensor Mod.
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Message:
Just thought about this. All current IAT mods I've seen have a switch to either bypass the stock IAT or use it. So if you turn the mod on, you have to adjust the temp to a colder temp relative to the outside. I think I've found a way to make it work realtive instead of absolute.
Correct me if I'm wrong, but the IAT is just a theresistor. AKA a big thermally variable resistor. The PCM passes current through it, and reads the voltage coming out of it. The higher the temp, the higher the resistance and hence higher voltage. V=i*R
So to trick the PCM we need to lower the resistance in the system. In theory we should be able to bridge the sensor with a rheostat (dial variable resistor) that would acomplish the task. Since resistance is inversly additive:
1/Rnet = 1/R1 + 1/R2.....
lowering the resistance of the bridge would lower the resistance of the system, thus fooling the PCM into thinking it's a colder temp. I would still put it on a rocker switch, as there is not such thing as an infinate resistance rheostat. Anyway, what do all you experts out there think of this idea? If the IAT is as simple as it looks, this should work.
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Buck
Dodge Dakota
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11/14/2003
18:00:18
| RE: New IAT sensor Mod.
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Message:
What you have just explained is the IAT adjuster...Already been thought up
Buck
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Matt
Dodge Dakota
JOIN HERE
11/14/2003
18:10:54
| RE: New IAT sensor Mod.
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From the diagrams of the adjustors I've seen it just switches between the rheostat and the IAT. (IE speedtweaks) Are adjustors like this commercially available?
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J and J Auto
GenII
11/14/2003
19:26:10
| RE: New IAT sensor Mod.
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Message:
Look at this thread I just listed all the parts
you need to build one
http://www.dodgedakota.net/boards/v6/2050-1.html
Larry
J&J Auto
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Matt
Dodge Dakota
JOIN HERE
11/15/2003
02:42:00
| RE: New IAT sensor Mod.
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Message:
Okay, I'm still not sure you guys are under standing me, so I have pictures this time.
This is the mod as presented in the thread:
Origional Config
When the switch is set to stock mode:
stock
The current (yellow) bypasses the theostat and goes straight from the PCM to the IAT.
Flipping the switch causes this set up:
Switch on
Note now that the current is running through the mod rheostat but not the IAT sensor. This means that there is no input from the IAT at all.
Now onto the other mod.
With the switch in the open position, again no power runs through the mod. The PCM only reads voltage from the IAT.
stock, mod2
When the switch is closed, the rheostat is now in parallel with the IAT:
Switch closed
Current is still running through the IAT. So if the rheostat is set to near infinate resistance, the PCM will read the stock setting. As resistance is decreased, the voltage will increase causing a change in the IAT signal. So the signal recieved by the PCM will be different for the same dial setting, if the IAT is reading a different temp.
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Buck
Dodge Dakota
JOIN HERE
11/15/2003
13:53:27
| RE: New IAT sensor Mod.
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Message:
I still dont understand....why go to all that trouble when you can go to rat shack, get the parts, make the IAT, Calibrate it, Install it and be on your merry way in a couple hours??
Buck
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J and J Auto
GenII
11/15/2003
14:07:34
| RE: New IAT sensor Mod.
IP: Logged
Message:
I understand what your saying
Using the exsisting IAT but altering the signal
with a resistor or pot but still using the IAT
to change value with heat
Like changing it form 100 to 80 degree's but also
if its 80 it would read 60.
Yes if you figure out the right resistor to use
you could alter the signal across the board and
it can tell the comp a cooler temp like 20 less
than it actualy is everywhere in its range
You could acomplish that by putting a resistor in
either wire like 25 50 or a 100 ohm maybe even a
10 ohm always just reading a little less than it
actualy is
Larry
J&J Auto
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