Modify L-Jet Temp II sensor or up fuel pressure?
07-26-2004, 05:31 AM
#16
Burning Brakes
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PorKen,
Methinks I should have been more specific.
Perhaps think of it this way - Temp II (and I for that matter) are both NTC Negative Temperatur Coefficient) thermistors - that is, the hotter they get, the less resistance they have to the flow of electricity. At room temp, they resist to the tune of ~2-3K Ohms. (Stealing the LH table here, but L's about the same curve...)
32F = 4.4-6.8 K Ohm
86F = 1.4-3.6 K Ohm
104F = .9-1.3 K Ohm
140F = 480-720 Ohm
176F = 250-390 Ohm
So, at a point, they get really close to 0 ohms resistance.This is why I was suggesting a slightly wider pot. But, this depends on how you hooked it up (series v. parallel).
For engineering drawings, we tend to look at electricity as flowing from "+" to "-" the geeks call this 'technical flow'. The reality of electron flow is just the opposite. The actual electron flow is from "-" to "+".
Therefore, the power is actually flowing *from* the block, through the Temp II sensor and ultimately to the ECU. The amount of power passed through Temp II is referenced to the known battery voltage (hence why all the grounds are at the same place) and then becomes part of the pulsewidth calculation.
Long story short - it has to be 12V, its power comes from the block ground, passed through the NTC resistor and the (temp varied) remnant is used as part of the fuel delivery calcs.
Make sense?
BTW - This nomenclature can get really confusing if you're used to working with AC current. In AC, you have "hot", "neutral", and "ground". Neutral and ground are basically the same thing with two different wires. Hot is where the "action" is.
In a 12V negative ground vehicle (like 99.9999%) of the cars on the road, negative (or "ground") is where the action is. Dumb, huh?
Greg
Methinks I should have been more specific.
Perhaps think of it this way - Temp II (and I for that matter) are both NTC Negative Temperatur Coefficient) thermistors - that is, the hotter they get, the less resistance they have to the flow of electricity. At room temp, they resist to the tune of ~2-3K Ohms. (Stealing the LH table here, but L's about the same curve...)
32F = 4.4-6.8 K Ohm
86F = 1.4-3.6 K Ohm
104F = .9-1.3 K Ohm
140F = 480-720 Ohm
176F = 250-390 Ohm
So, at a point, they get really close to 0 ohms resistance.This is why I was suggesting a slightly wider pot. But, this depends on how you hooked it up (series v. parallel).
For engineering drawings, we tend to look at electricity as flowing from "+" to "-" the geeks call this 'technical flow'. The reality of electron flow is just the opposite. The actual electron flow is from "-" to "+".
Therefore, the power is actually flowing *from* the block, through the Temp II sensor and ultimately to the ECU. The amount of power passed through Temp II is referenced to the known battery voltage (hence why all the grounds are at the same place) and then becomes part of the pulsewidth calculation.
Long story short - it has to be 12V, its power comes from the block ground, passed through the NTC resistor and the (temp varied) remnant is used as part of the fuel delivery calcs.
Make sense?
BTW - This nomenclature can get really confusing if you're used to working with AC current. In AC, you have "hot", "neutral", and "ground". Neutral and ground are basically the same thing with two different wires. Hot is where the "action" is.
In a 12V negative ground vehicle (like 99.9999%) of the cars on the road, negative (or "ground") is where the action is. Dumb, huh?
Greg
07-28-2004, 03:13 AM
#17
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Going through the hood release grommet was supprisingly easy. Remove the dead pedal, pull the carpet down and remove the handy insulation plug (there were two blank holes on my car):
The pot is wired in series, adding to the value of the Temp II sensor.
I found, during a short highway drive tonight, that it does not make much difference at colder (60F) temps; the reaction on the mixture meter is much more evident at higher (90F) temps. I need to unplug the O2 sensor and recheck.
The pot is wired in series, adding to the value of the Temp II sensor.
I found, during a short highway drive tonight, that it does not make much difference at colder (60F) temps; the reaction on the mixture meter is much more evident at higher (90F) temps. I need to unplug the O2 sensor and recheck.
