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Old 01-03-2008, 03:24 PM   #1
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Default What value R7 and R8 for CLT sensor?

I know this is an Asked-and-Answered question, but the answers all seem contradictory.

Assuming I am building a standalone 3.0 MS-I, and using the stock 1.6 CLT sensor, what values of R7 (the CLT pullup) and R8 (the CLT offset) should I use?
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Old 01-03-2008, 03:32 PM   #2
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You keep R7 and use the one that comes in the kit 2.49ohm. Keep the R8 thats in there too.
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Old 01-03-2008, 03:34 PM   #3
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Ah ha- fast edit there, Sam.

Yeah, this is not a piggyback install. There must be some value of R7, just wasn't sure whether the stock value was best, or some other value.
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Old 01-03-2008, 03:36 PM   #4
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stock ecu coolant is 2490,
R7 is 2490,

so 2490 for bias when you flash it, since you wont have the ecu in place.
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Old 01-03-2008, 03:50 PM   #5
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So if I followed Braineacks megasquirt build and am using the OEM ecu to control idle because i have AC, I would use 2490 for the bias resistor for the clt because i left R7 out? This is just to make sure.

Also, for the GM IAT sensor i'd use 2490 as the bias resistor also?
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Old 01-03-2008, 03:55 PM   #6
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yep.

or if you leave r7 installed, use 4980.
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Old 01-03-2008, 04:00 PM   #7
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What year is your car supersuk. It seems the 1.6s can use 2490. 96-97 need to use 1205 ohms. Not sure about 94-97. Always leave R7 out in a parallel install.
GM IAT use 2490 with R4 installed.


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Old 01-03-2008, 04:11 PM   #8
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Originally Posted by cjernigan View Post
What year is your car supersuk. It seems the 1.6s can use 2490. 96-97 need to use 1205 ohms. Not sure about 94-97. Always leave R7 out in a parallel install.
GM IAT use 2490 with R4 installed.


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I'm not sure I believe my own post about the 1205 on 96-97. my coolant temp only reads 65* (is was in the 20s this morning) - 215*. It's not so great for my cold start when the MS won't read below 65*
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Old 01-03-2008, 04:13 PM   #9
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got a DDM? just check the resistance really fast on the harness.
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Old 01-03-2008, 04:16 PM   #10
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Thats interesting. Saml01 is using your 1205 and says its only like 8* off what his home thermo says.
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Old 01-03-2008, 04:36 PM   #11
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Thats funny because my car is a 90 and in order to get the temp readings right I had to use somewhere around 1200 for the bias resistor. I did replace the coolant sensor about a year ago with a part i bought from checkers I think. Think they gave me the wrong part?

Oh one more thing, my GM IAT sensor is about 20degrees off. Its reading that much cooler so i had to offset the linear line by about that much. Now after leaving the car to cool down over night i get temp readings that are about 3-5 degrees off from each other.
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Old 01-03-2008, 05:00 PM   #12
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Quote:
Originally Posted by cjernigan View Post
Thats interesting. Saml01 is using your 1205 and says its only like 8* off what his home thermo says.
No no. The GM AIT is the same as my home thermo, its the CLT thats off by 8 degrees. 8 Degrees to low lower then the AIT.

Tonight im gonna go out and check the readings since the temps are in the 20's.
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Old 01-06-2008, 03:44 PM   #13
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Quote:
Originally Posted by Saml01 View Post
No no. The GM AIT is the same as my home thermo, its the CLT thats off by 8 degrees. 8 Degrees to low lower then the AIT.

Tonight im gonna go out and check the readings since the temps are in the 20's.
Did you check your low temp readings? I replaced my sensor today after verifying the readings. It is definitely the same values as the RX7 unit so it's not an easytherm value thing. It has to either be a hardware defect of some kind, or wrong bias resistance. Check yours in the 20-30s and let me know what it reads.

Anyone see CLT go over 215*? Mine never has.
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Old 01-06-2008, 10:50 PM   #14
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Quote:
Originally Posted by Arkmage View Post
Did you check your low temp readings? I replaced my sensor today after verifying the readings. It is definitely the same values as the RX7 unit so it's not an easytherm value thing. It has to either be a hardware defect of some kind, or wrong bias resistance. Check yours in the 20-30s and let me know what it reads.

Anyone see CLT go over 215*? Mine never has.
Mine never has either.

Check what in the 20's and 30's?
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Old 01-06-2008, 11:07 PM   #15
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I have seen coolant over 215. Lots of boost during a 95* day with stock radiator, no shrouding or undertray. My coolant readings are ***** on accurate with outside temps though.
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Old 01-07-2008, 09:55 AM   #16
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Quote:
Originally Posted by Saml01 View Post

Check what in the 20's and 30's?
check CLT temp... make sure your's reads below 65* when it's cold out. It's warmed up here now so I can't see if my reflash fixed it until the next time I can't start it.
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Old 01-07-2008, 11:25 AM   #17
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Quote:
Originally Posted by Arkmage View Post
check CLT temp... make sure your's reads below 65* when it's cold out. It's warmed up here now so I can't see if my reflash fixed it until the next time I can't start it.
All the time. Last week it was like 20 degrees out and it was reading 8 below the AIT as usual.
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