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Incorrect coolant temperature reading

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Old 07-10-2007, 09:48 AM
  #21  
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Originally Posted by mschlang
Better yet, jumper it on the backside. Resistence goes to ~0 and easy to remove.
not a bad idea....but it should be easy enough to tap the underside with the iron and pull it out. We'll see.
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Old 07-10-2007, 01:05 PM
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tried jumping it, but I got no readings at megasquirt and it wouldn't idle. Guess I gotta do some math and redo easytherm.
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Old 07-10-2007, 07:11 PM
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Jumping it gives a 0 ohm resistance, removing it gives an infinite resistance, jumpering it will not do that same job.
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Old 07-11-2007, 01:06 PM
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Oops, zero and infintity. So close, yet so far apart.
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Old 07-11-2007, 03:02 PM
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yeah found that out the hard way thought about it after the fact.
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Old 07-12-2007, 04:30 AM
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Where is this "Voltage at the MS Tap"? Is this the 12V live feed to the MS ECU?
Also, my 1990 1.6 doesnt have that 6 pin connector above the fuel rain that I can see, any other places I can get the reading form?

Last edited by richard_ha; 07-12-2007 at 06:13 AM.
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Old 07-13-2007, 02:19 PM
  #27  
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So I got a new resistor today and put it in r4. My IAT temp came back to reading correctly and now hy coolant is alot better. I still think it is about 10degrees low but I am happy with where it is at now. So after all this if you want to use the Mazda CLT and GM IAT just remove r7.
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Old 07-15-2007, 08:20 PM
  #28  
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Originally Posted by richard_ha
Where is this "Voltage at the MS Tap"? Is this the 12V live feed to the MS ECU?
Also, my 1990 1.6 doesnt have that 6 pin connector above the fuel rain that I can see, any other places I can get the reading form?
Or does anyone just know the value for a 1990 1.6?
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Old 07-16-2007, 11:35 AM
  #29  
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So whats the final verdict here?

I'm guessing the most common combo is mazda CLT and GM IAT.
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Old 07-16-2007, 11:49 AM
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yeah it is.

R7 should be pulled if so. Mine reads 30° low with it installed.
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Old 07-21-2007, 10:10 PM
  #31  
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So... pulled R7... and configured via easytherm. I'm getting a solid 77 CLT and a -6 IAT... this is with updating to 029w.

I couldn't even tune the car today with it running off those iat/clt settings :(.

For the pulling R7... we are talking standalone right?

I'm bummed... i managed to drive it outta warehouse again... partway down street and back... its too rich to drive and not tunable with bad sensor input.

I have another issue... but i'll bring it up separately.
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Old 07-21-2007, 11:15 PM
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since you aren't sharing them with any other ecu, then you'd probably want to keep both in.

pulling r7 is if you are sharing the sensor with the stock ecu, as the oem ecu has it's own bias resistor. Keeping r7 installed adds resistance and throws the reading off 20° or so.
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Old 07-21-2007, 11:38 PM
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Well crap....

So with r7 out... it would explain my CLT reading incorrectly... but not IAT.

I'm running stock mazda CLT... gm IAT....
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Old 07-22-2007, 12:20 PM
  #34  
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I think the stock CLT bias resistor is somewhere all ready in the line when you tap and share. Did you use the same values for easy therm as I have podted int he first post? I am with those now and they are about dead one.
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Old 07-22-2007, 01:38 PM
  #35  
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I used those values. In easy therm and the GM values for the IAT. I then created the proper files, copied them over to megatune folder. I also used easytherm to update the s19 file... of which I'm using version 029w.

Bad clt and bad IAT... IAT is bad because I've pulled R7 now.... so I'll have to fix that.
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Old 07-22-2007, 02:05 PM
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I've also lost tach signal to the cluster... it was glitchy for a bit... then most recent startup it doesn't do anything. MS is clean rpm signal though.
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Old 07-22-2007, 08:32 PM
  #37  
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Ignitors for the tach problem I think. Jerry form DIY said his tach in the dash went out but still worked in MS.
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