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altering the ect
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fixityourselfer Offline
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Post: #1
altering the ect
some info on my car's ect: as the car warms up the ohms drop. if i'm not mistaken , the ect will read just under 300 ohms right when it reaches operating temp. after a 15 minute drive the other day my ect read 225 ohms. at 70F it's like 1000-2000.

the other day just for kicks i (temporarily)replaced the ect with a 270 ohm resistor to see if i could get the car out of open loop quicker cuz the car gets me horrible mileage for that first 3 or 4 mins or so until its warm and in closed loop. 65F outside, cold engine started right up, temp needle went right to what the car THOUGHT was operating temp and no code was set in the 15 min or so that i drove around like that.fan was not on at 270 ohms. after a cooler night the cold engine wouldn't start.

but anyways, here's my question, (and the reason for this post) how do i mod the ect to give a reading of say, 15-20 ohms (or whatever is necessary) lower then what its supposed to do? i understand doing this may turn on the fan a little more often, but i'm not concerned about that.

i understand adding a resistor to the the ect would increase the resistance...and wouldn't be what i want to do.
(This post was last modified: 05-21-2009 04:16 PM by fixityourselfer.)
05-21-2009 04:14 PM
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jbalat Offline
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Post: #2
RE: altering the ect
Wikipedia says that ECT is European Central Time, is this what you mean ?

I assume you mean IAT or CTS ?

If you want the ohms to decrease as temp increases then you need to add a resistor in parallel
The formula is 1/Rt = 1/R1 + 1/R2

Rt= Required resistance... (you need to chart actual Resistance vs actual Temp and then pick an Rt value from the chart that gives a +10 degree offset)

R1=nominal resistance at the nominal temperature as per the chart (use an area of the chart near the temperature you will get after the car has warmed up)

R2 = Your Resistor you want to solve for

So 1/R2 = 1/Rt - 1/R1
Then Just invert to get R2

Is that what you wanted ?
05-22-2009 09:39 PM
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fixityourselfer Offline
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Post: #3
RE: altering the ect
Is that what you wanted ?
[/quote]

Yes! thanks alot man....
for some reasons my volvo manuals refer to the coolant temp sensor as the ect. it seems to stand for Engine Coolant Temperature. i thought it was strange too.
05-23-2009 07:21 PM
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