Can I use an FD IAT sensor in my TII insted of an FC one? I am gonna change the FC one for an FD one ,when I finally get round to installing my Apexi PFC. But im just wondering if I can do it now as I have the inlet in bits at the moment. If I install it will the stock ECU throw a wobbly?
Not sure to be honest - if you have a hair dryer, thermometer and a multimeter, you can test both units and see what resistance they are at different temperatures.
Alternatively, look in the manuals for the specs at set temperatures - both units are thermistors, so likely going to be the same sort of sensor, but the values at 25, 70 and so on are critical as the ECU is set for that sensor range. I\'ve got details for the FC one in an Excel spreadsheet, but don\'t have access to an FD AIT to compare it with.
Answer is yes but you will have to change the plug and retap the hole as its a different thread but you can use the IAT sensor to do that job if you are careful as its very close in thread pitch.
Its what i have done on mine but i did use a FD racing IAT which is a faster acting device and I do have a Apexi, however I have not altered any settings to do with temps.
part of the mod to fit a Apexi is to use a FD IAT amongst other things, even with the FC specific Apexi ECU
Yeah I know about using the FD one for the Apexi ecu. This is the reason I want to fit it now to save me taking it all to bits again to re-tap the hole. Think the FC one is M10 x 1 and the FD one is M10 x 1.25. Only trouble is the Greddy comp tube I have has been tapped out to M12 so I have to make a bung then redrill/ tap it. Hence only wanting to do it once.
I had a quick play with them both yesterday and they seem to react differently as you heat them. The FD one seemed to act slower. The resistance dropped slower when it was heated compared to the FC one. It is a different style sensor though so maybe its meant too. I would have thought though that the resistance should have gone up as it heated up not down.
Anyway so yopu think I can use it with a stock ecu Pete?
The electrical resistance of an object is a measure of its opposition to the passage of an electric current. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material.
Discovered by Georg Ohm in 1827,[1] electrical resistance shares some conceptual parallels with the mechanical notion of friction. The SI unit of electrical resistance is the ohm (Ω). Resistance\'s reciprocal quantity is electrical conductance measured in siemens.
For a wide variety of materials and conditions, the electrical resistance does not depend on the amount of current through or the potential difference (voltage) across the object, meaning that the resistance R is constant for the given temperature and material. Therefore, the resistance of an object can be defined as the ratio of voltage to current, in accordance with Ohm\'s law:
In the case of a nonlinear conductor (not obeying Ohm\'s law), this ratio can change as current or voltage changes; the inverse slope of a chord to an I–V curve is sometimes referred to as a "chordal resistance" or "static resistance".
A metal consists of a lattice of atoms, each with a shell of electrons. This is also known as a positive ionic lattice. The outer electrons are free to dissociate from their parent atoms and travel through the lattice, creating a \'sea\' of electrons, making the metal a conductor. When an electrical potential difference (a voltage) is applied across the metal, the electrons drift from one end of the conductor to the other under the influence of the electric field.
Near room temperatures, the thermal motion of ions is the primary source of scattering of electrons (due to destructive interference of free electron waves on non-correlating potentials of ions), and is thus the prime cause of metal resistance. Imperfections of lattice also contribute into resistance, although their contribution in pure metals is negligible.
The larger the cross-sectional area of the conductor, the more electrons are available to carry the current, so the lower the resistance. The longer the conductor, the more scattering events occur in each electron\'s path through the material, so the higher the resistance. Different materials also affect the resistance.
Temperature dependence
Near room temperature, the electric resistance of a typical metal increases linearly with rising temperature, while the electrical resistance of a typical semiconductor decreases with rising temperature. The amount of that change in resistance can be calculated using the temperature coefficient of resistivity of the material using the following formula:
where T is its temperature, T0 is a reference temperature (usually room temperature), R0 is the resistance at T0, and α is the percentage change in resistivity per unit temperature. The constant α depends only on the material being considered. The relationship stated is actually only an approximate one, the true physics being somewhat non-linear, or looking at it another way, α itself varies with temperature. For this reason it is usual to specify the temperature that α was measured at with a suffix, such as α15 and the relationship only holds in a range of temperatures around the reference.[4]
At lower temperatures (less than the Debye temperature), the resistance of a metal decreases as T5 due to the electrons scattering off of phonons. At even lower temperatures, the dominant scattering mechanism for electrons is other electrons, and the resistance decreases as T2. At some point, the impurities in the metal will dominate the behavior of the electrical resistance which causes it to saturate to a constant value. Matthiessen\'s Rule (first formulated by Augustus Matthiessen in the 1860s; the equation below gives its modern form) [5][6] says that all of these different behaviors can be summed up to get the total resistance as a function of temperature,
where Rimp is the temperature independent electrical resistivity due to impurities, and a, b, and c are coefficients which depend upon the metal\'s properties. This rule can be seen as the motivation to Heike Kamerlingh Onnes\'s experiments that led in 1911 to discovery of superconductivity. For details see History of superconductivity.
Intrinsic semiconductors become better conductors as the temperature increases; the electrons are bumped to the conduction energy band by thermal energy, where they flow freely and in doing so leave behind holes in the valence band which also flow freely. The electric resistance of a typical intrinsic (non doped) semiconductor decreases exponentially with the temperature:
Extrinsic (doped) semiconductors have a far more complicated temperature profile. As temperature increases starting from absolute zero they first decrease steeply in resistance as the carriers leave the donors or acceptors. After most of the donors or acceptors have lost their carriers the resistance starts to increase again slightly due to the reducing mobility of carriers (much as in a metal). At higher temperatures it will behave like intrinsic semiconductors as the carriers from the donors/acceptors become insignificant compared to the thermally generated carriers.[7]
The electric resistance of electrolytes and insulators is highly nonlinear, and case by case dependent, therefore no generalized equations are given.
dam it never copied the forula,lol personnally I would fit it as its a known mod, the worse that can happen is that you might get more or less fuel in relation to temps. I will try and dig out the notes for you to confirm.
lol, bet you wished you never asked, amazing what you can google lol
Both the FC and FD IAT sensors are thermistors. Thermistors are resistors whose resistance varies logarithmically with temperature, and they come in two main varieties - PTC and NTC. PTC or Positive Temperature Coefficient increase in resistance as they get warmer, whereas NTC (Negative ....) decrease in resistance.
In the ECU, the sensor forms one leg of a potential divider, with a fixed resistor being the other part of the resistance chain. 5 Volts is fed accross the top of this divider chain, and then the voltage at the junction of the components is read by an analog to digital converter for the ECU to work with.
What you end up with is a voltage that varies with resistance - in the case of the FC IAT sensor - this voltage is somewhere close to 4.7V at 0 degrees C and goes down to about 0.6V at 120 degrees C. At 25C the manual says this is resistance is 33K - which gives a voltage of 4.06V. The sensor was chosen so that it\'s greatest resistance changes occur at the lower end of the temperature curve, as that\'s where correction is most needed.
I was going to attach the spread sheet I used for my gizmo that measures Water and IAT temps, so you\'ve got all the resistance values in the 33K column for different temps - easiest ones to measure are 0C, ambient and 100C as you can replicate these temperatures with relative ease for testing, but it won\'t let me - these resistances are 121K at 0, 33K at 25C and 1.87K at 100
If the FD sensor is around about 33K at 25C, then it will most likely work with the stock ECU. Manual says give or take 4K !
Gulp! My head hurts now!
Thanks guys. Thumbs up. Guess i\'ll try it then.
As long as you keep that sensor in a stock position as the ECU has been setup for this very position. Only move a sensor if you have the means to alter the mapping and directly the calibration of that sensor. if i can get some values from my datalogit from cold to fully hot then i will post up on here. I am running the faster acting IAT but this is FD specific and designed to be a direct replacement, with your stock ECU it will always work but you have to be careful you do not lean her out until you have a way to monitor AFR\'s.
good sources of info:
https://docs.google.com/fileview?id=0BzoEDgrFUehAMTRiNTlmMWMtNzgzNi00Mzk1LThkYTUtMGUwMWY1MTkxODA2&hl=en
FC=
+/- 10 %
20C = 41.5k ohms
50C = 11.8k ohms
85C = 3.5k ohms
without one in front of me but i think the FD is a delco curve
delco curve-
-20C = 14k-17k ohms
20C = 2.2k- 2.7k ohms
80C = 0.29- 0.35k ohms
if you grab your FD sensor it would be easy enough to replicate this in the oven
and confirm ===
F = ( C x 9/5 ) + 32
50C = 122F
80C = 176F
85C= 185F
looks like i am right
FC and 13b RE ( cosmo )
°C--R(kOhm)
-40--1 116.000
-20--325.900
0--109.400
20--41.390
50--11.610
70--5.522
85--3.315
100--2,062
125--1,002
127 comp--0.939
FD 13b REW
*C ------ Kohms
-40 ------ 25.525
-20 ------ 16.2
0 ------ 6.875
20 ------ 2.45
35 ------ 1.7575
50 ------ 1.065
65 ------ 0.6925
95 ------ 0
FD 13b REW is using the standard "delco" curve
for both water and air temp
FC 13bt and cosmo 13b RE ( and likely 20B )
use a "delco" curve for the coolant temp sender
and a "denso" ( or "bosch" ) curve for the air temp sender
PS
its looking like some sort of toyota is going to be the easiest donor if you can\'t source another FC air temp sender
double check resistance at 20 C and maybe 80C to confirm
edit above post,, bosch "A" curve is the same as delco , suit FD
I\'ve managed to make an adapter for my compression tube to house the standard FC IAT sensor. M12x1.75 to 1/8bsp. Turns out the sensor isn\'t a metric fine thread its 1/8 bsp who\'d have thought! Now at least I can run it on the stock ecu untill I can afford to install my Apexi PFC and have it mapped correctly.
Thanks for all the help people.
Well I have been running the car for a week or so using the FC IAT sensor. I think I have come to the conclusion that the sensor isn\'t working well enough to cope with the new intake set up. I don\'t think it sits far enough into the inlet tube to work correctly. Either that or it can\'t react quick enough to the change in temps. Im saying this cause the car hesitates under boost and coughs and pops:) alot more. If im gentle on the throttle it is ok though. Also I can\'t seem to control the boost as well as I could before using my controller although Im not getting major boost spikes it is reaching 10psi with the controller turned right down. This may also be contributing to the problem.
On a good note though the new intercooler/intake set up seems to be a lot free-er flowing and the engine seems to like this at lower rpm\'s :)
I don\'t think you\'re AIT sensor is causing the stumble - it\'s on one of the slower feedback loops in the ECU - meaning it\'s readings are averaged out over longer periods of time to control additional fuel if cold.
Top end stumble could be spark strength, turbulence on the air intake, or you may just be maxing out the stock AFM, and on the stock ECU, only the map sensor will be controlling extra fuel - this is the area I\'ve had most work to do in the emange - apart from the idle.
Yeah I think its time I got the Apexi PFC in and mapped. Just really short of £\'s right now as we are looking to move house and me and the missus are having another baby in March. On the plus side though the house we are looking at has a room especially for the FC which she has never had before since I have owned her :)
Do you know if the base map on the PFC would be ok to run for a while untill I could spare some cash? I don\'t know what the base map is on the PFC\'s.
The base map is just that - it\'ll get the car started and get you places off boost - very important that you stay off boost too !
Basically it will let you start the car / run it in gently and then get you to a tuner.
Congratulations on the arrival to come - seems everyone\'s at it :)
I really don\'t know how these stuffs works on my car, It just happened that I go to my trusted mechanic to fix it.
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