ECU temp v. Radiator inlet temp (coolant) - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 02-12-2008, 08:04 PM   #1
Junior Member
Thread Starter
 
Join Date: Sep 2007
Posts: 108
Total Cats: 0
Default ECU temp v. Radiator inlet temp (coolant)

Has anyone compared the temperature of the coolant at the ECU temp sensor (logged I assume) and the coolant at the input to the radiator (close to the thermostat and its thermal sensor - with the coolant valve fully open, engine running)?
aseer is offline   Reply With Quote
Old 02-12-2008, 08:41 PM   #2
Elite Member
iTrader: (13)
 
cjernigan's Avatar
 
Join Date: Oct 2006
Location: Atlanta, GA
Posts: 8,147
Total Cats: 6
Default

I haven't seen anything about it. It might exist though. There shouldn't be much difference between the two though considering the coolant in the radiator inlet and CLT sensor are both in or coming from the head. I would suspect the CLT sensor to read higher because it is in the back of the head where coolant flow is lesser and normally hotter.
Atleast that's my WAG.
cjernigan is offline   Reply With Quote
Old 02-12-2008, 08:47 PM   #3
Junior Member
Thread Starter
 
Join Date: Sep 2007
Posts: 108
Total Cats: 0
Default

Quote:
Originally Posted by cjernigan View Post
I haven't seen anything about it. It might exist though. There shouldn't be much difference between the two though considering the coolant in the radiator inlet and CLT sensor are both in or coming from the head. I would suspect the CLT sensor to read higher because it is in the back of the head where coolant flow is lesser and normally hotter.
Atleast that's my WAG.
Thanks, I took a modified radiator cap and stuck a thermocouple through it into the coolant flow and saw about a 20F difference (20F cooler at the radiator compared to what my MSPNP was reading, once the valve opened and long enough to reach steady state - the thermocouple was calibrated).
I did not have a feel for what to expect however.
aseer is offline   Reply With Quote
Old 02-12-2008, 09:01 PM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,847
Total Cats: 1,788
Default

why do you wanna know? id wanna know how hot the coolant just leaving is, not how cool the fluid entering is...
Braineack is offline   Reply With Quote
Old 02-12-2008, 09:05 PM   #5
Junior Member
Thread Starter
 
Join Date: Sep 2007
Posts: 108
Total Cats: 0
Default

Quote:
Originally Posted by Braineack View Post
why do you wanna know? id wanna know how hot the coolant just leaving is, not how cool the fluid entering is...
I wanted to get a feel for how different my fan control temperature would be if I used the MSPNP control compared to using the thermal sensor at the thermistor near the radiator (which is how I think the stock cooling fan is controlled).

{I have a 91, not sure if that makes a difference}

Last edited by aseer; 02-12-2008 at 11:19 PM.
aseer is offline   Reply With Quote
Old 02-13-2008, 12:40 AM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,847
Total Cats: 1,788
Default

itll probably be close enough. thermoswitch sits behind the thermostat, and once open that's where most the flow goes, so im sure it's within 10 of #4.
Braineack is offline   Reply With Quote
Old 02-14-2008, 01:06 AM   #7
Junior Member
Thread Starter
 
Join Date: Sep 2007
Posts: 108
Total Cats: 0
Default

Quote:
Originally Posted by aseer View Post
Thanks, I took a modified radiator cap and stuck a thermocouple through it into the coolant flow and saw about a 20F difference (20F cooler at the radiator compared to what my MSPNP was reading, once the valve opened and long enough to reach steady state - the thermocouple was calibrated).
I did not have a feel for what to expect however.
I redid the measurements, the differential is closer to 11 degrees as suggested by Braineack; 11 degrees hotter at the head compared to the stock fan switch point (though my MSPNP seems to read CLT in 4 degree increments so the differential error is on that order - can I reduce the granularity through Megatune or some other mechanism?).
aseer is offline   Reply With Quote
Old 10-01-2009, 06:15 PM   #8
Junior Member
 
Join Date: Jul 2005
Location: Hillsborough, NC
Posts: 273
Total Cats: 0
Default

Well, it's an 8 bit variable, so the cpu is going to see it as a value between 0 and 255 (so only 256 possible values across the temperature range). Take a look at thermfactor.inc and you'll see the mapping. It looks like the range is from -96F to 408F. If you narrowed the range down to something that would work in your climate, you could get more resolution.

You'll need to reload the firmware with the new table if you make changes.
JustinHoMi is offline   Reply With Quote
Old 10-01-2009, 06:30 PM   #9
Elite AbsurdFlow Member
 
Laur3ns's Avatar
 
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11
Default

Quote:
Originally Posted by aseer View Post
Has anyone compared the temperature of the coolant at the ECU temp sensor (logged I assume) and the coolant at the input to the radiator (close to the thermostat and its thermal sensor - with the coolant valve fully open, engine running)?
My MSPNP shows 83C and my VDO gauge shows 83C when the engine is warm. The VDO sensor is just before the radiator inlet.

They only differ during warmup when the stat hasnt opened yet.
Laur3ns is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
MSPNPPro-MM0105: Coolant Temperature Output slomiata MEGAsquirt 5 10-07-2015 02:11 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
Recommended Tire Temp for best friction thumpetto007 Race Prep 4 09-27-2015 06:16 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:40 AM.