Calling Ben Isle 5 - Please help us find out the 96/97 CLT Bias Resistance. - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-11-2008, 05:19 PM   #1
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Default Calling Ben Isle 5 - Please help us find out the 96/97 CLT Bias Resistance.

As most of you know the 96/97 cars have a different CLT bias resistance then all the other cars. In a for sale thread, Ben said that with a proper thread and appropriate information he will help us take a direct measurement of the bias resistor inside the factory ECU.(at least thats what I understood from his post).

Right now I am running 1540 which was discovered by Arkmage and while very accurate, withing 5-8* of the MAF, it would be nice to have it even more accurate to prevent the CLT temp from pegging at 215 when the engine is fully warm.

We need to help him locate the appropriate resistor inside the ECU. I dont have a picture, and I dont know how to explain which one it is.

So. Anyone know how to help him find the proper resistor to take a direct measurement?
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Old 03-11-2008, 05:23 PM   #2
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what temp does the fans come on?

MSI doesn't go higher than 215F CLT.


you wont be able to figure it out with a DMM on the ecu....
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Old 03-11-2008, 05:27 PM   #3
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Originally Posted by Braineack View Post
what temp does the fans come on?

MSI doesn't go higher than 215F CLT.


you wont be able to figure it out with a DMM on the ecu....
Youre saying you cant directly measure the Bias resistor inside the ecu?

Fans come on around, based on factory spec, 207*? I think
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Old 03-11-2008, 05:32 PM   #4
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signal goes through like 3 resistor. heck on my 1.6L ecu the AIT signal shares 2 of the resistors from the CLT signal.

if i add the resistors up i get 15000ohm and 10000ohm each. if i take the resistance at the connector i get 3630ohm. The actual bias resistance is really close to 2625 ohm.

you'll never read over 215 with MSI, so if the fans are kicking on at the right spot, you have the right value.
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Old 03-11-2008, 05:32 PM   #5
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Originally Posted by Saml01 View Post
Youre saying you cant directly measure the Bias resistor inside the ecu?

Fans come on around, based on factory spec, 207*? I think
You would actually have to remove it before trying to measure the resistance. If you didn't you'd be measuring the entire resistance of the circuit it is attached to.
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Old 03-11-2008, 05:37 PM   #6
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Quote:
Originally Posted by Braineack View Post
signal goes through like 3 resistor. heck on my 1.6L ecu the AIT signal shares 2 of the resistors from the CLT signal.

if i add the resistors up i get 15000ohm and 10000ohm each. if i take the resistance at the connector i get 3630ohm. The actual bias resistance is really close to 2625 ohm.

you'll never read over 215 with MSI, so if the fans are kicking on at the right spot, you have the right value.
Thats gonna be a pain in the *** to reprogram the MS a few times to get closer to the right number.

Do I have to make bias lower or higher to make it read lower?
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Old 03-11-2008, 05:40 PM   #7
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Quote:
Originally Posted by Braineack View Post
you'll never read over 215 with MSI
uhm.. really? that's no good.
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Old 03-11-2008, 05:46 PM   #8
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so it seems with the 8-bit resolution...

I'm wondering if we remove some of the -40 to -20 degree CLT temps, we can add 20 more up top....so you can at least see to 235

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What you can't do, especially with the MS1 implementations, is enter values greater than 215 because of the 8-bit variable limitation in the processor. Remember, you have to also allow for values below 0 -- 215 + 40 = 256 distinctive values. However, now that we've got the MS2 with more horsepower, that limitation raised a little higher Smile

interesting read:
http://www.msefi.com/viewtopic.php?t=22517
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Old 03-11-2008, 05:49 PM   #9
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hmm... must be one of the reasons behind DIY releasing the new firmware with tweaked coolant temp stuff for my MSPNP.
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Old 03-11-2008, 06:25 PM   #10
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Originally Posted by Braineack View Post
so it seems with the 8-bit resolution...

I'm wondering if we remove some of the -40 to -20 degree CLT temps, we can add 20 more up top....so you can at least see to 235
In short, no unless you modify the code, and the f*****ng thing is in so many places, it's just gaaaaaah! (I've tried).

Jim
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Old 03-12-2008, 01:06 AM   #11
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In short, no unless you modify the code, and the f*****ng thing is in so many places, it's just gaaaaaah! (I've tried).

Jim
You cant write a script to get it all?
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Old 03-12-2008, 03:35 AM   #12
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Quote:
Originally Posted by Saml01 View Post
You cant write a script to get it all?
It's not a matter of writing a script, it's just that every function that takes CLT as a parameter, expects the CLT to be (CLT-40)F because of the said design. So, it's not that you will just "Find & Replace" every occurance of CLT with CLT+40 (remember this is assembly, not C).

Anyway, I just got bored and didn't want to overflow the code, the maxmem limit is already reached.

Jim
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Old 03-12-2008, 10:46 AM   #13
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^ OOOOOOH. Makes the sense.
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Old 03-12-2008, 11:05 AM   #14
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according to the link i posted, it seems some people are modding the thermfactor file to display higher temps based on the resistance curve, just not changing .s19 file burnt in MS....so at least it outputs on your screen and MS is none-the-wiser...
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