Focus Fanatics Forum banner

1 - 20 of 29 Posts

·
Registered
Joined
·
3,673 Posts
Discussion Starter #1
...but you probably knew that already.

Did you ever wonder why the temperature gauge gets to the halfway mark so quickly after you start the engine?

The gauge will hit the halfway mark with a coolant temp. of ~50C (122F). As the coolant temp. increases to normal operating temp. (~200F), the gauge won't move.

I don't know what the coolant temp. would have to be for the gauge to read significantly higher, but I imagine that it would start going up quickly when the coolant temp. gets above 210F or so.

The bottom line is that the temperature gauge is highly non-linear by design.
 

·
Registered
Joined
·
533 Posts
Hi, the bottom line is that most people don't look at the temp gauge and many cars don't have one anymore, just a blue light when it is cold and a red one when it is up to temp. I guess, though, if something is fitted it should work, more or less, as it should, maybe the gauge is just there to indicate that the engine temp is working within its designed parameters.
Chris
 

·
FF's Night Security
Joined
·
28,766 Posts
It's more likely a CHT sensor (cylinder head temp) only the SVT as a real water temp sensor from what I understand or can see. CHT is different than actual water temp, that's why I installed a water temp gauge in my gauge pod.
 

·
Registered
Joined
·
232 Posts
...but you probably knew that already.

Did you ever wonder why the temperature gauge gets to the halfway mark so quickly after you start the engine?

The gauge will hit the halfway mark with a coolant temp. of ~50C (122F). As the coolant temp. increases to normal operating temp. (~200F), the gauge won't move.

I don't know what the coolant temp. would have to be for the gauge to read significantly higher, but I imagine that it would start going up quickly when the coolant temp. gets above 210F or so.

The bottom line is that the temperature gauge is highly non-linear by design.
I posted in another thread about how darn quick the car seems to warm up. How do you know it's playing games with the actual temperature, i.e., not moving after 122F?
 

·
Registered
Joined
·
532 Posts
The car was designed to warm up quickly. If your car has the Kysor shutters, it should be closed automatically to aid in the warm up process. The reason is for the engine to operate as efficiently as possible, as well as to reduce emissions. Also, a side benefit is that the heat should come on quicker.
 

·
Registered
Joined
·
1,156 Posts
The car was designed to warm up quickly. If your car has the Kysor shutters, it should be closed automatically to aid in the warm up process. The reason is for the engine to operate as efficiently as possible, as well as to reduce emissions. Also, a side benefit is that the heat should come on quicker.
Yes. And, it does!
 

·
Registered
Joined
·
418 Posts
If you put your car in test mode,You can watch the warmup on the digital display.
You could take a video and work out the rate of change in temperature.(Data Log)
The ones without K shutters, like mine, warm up super fast as well.
The Mixture is super rich on startup and the idle is also fast for about a minute or 2.
The Kat needs to warm up quickly for emmisions control.
 

·
Registered
Joined
·
4,475 Posts
If you put your car in test mode,You can watch the warmup on the digital display.
You could take a video and work out the rate of change in temperature.(Data Log)
The ones without K shutters, like mine, warm up super fast as well.
The Mixture is super rich on startup and the idle is also fast for about a minute or 2.
The Kat needs to warm up quickly for emmisions control.
Yeah, I was going to say something similar about the test mode temperature gauge.
 

·
Registered
Joined
·
2,484 Posts
Min is an 07 so its a different car but it did that when i first got it, and my dads old truck did it also. I thought it was just a ford thing to rev way up at the start then slowly drop down to normal. Come to find out it runs lean at the start to quickly heat the cat up so it can do its job quicker.

If you ever watch most older cars smoke the most and put out the most pollution at the start so i think this is why it does it. I dont think its good for the car so i had Tom tune that out on mine. Mine sounds normal when it starts now.
 

·
Registered
Joined
·
3,673 Posts
Discussion Starter #12
It's more likely a CHT sensor (cylinder head temp) only the SVT as a real water temp sensor from what I understand or can see. CHT is different than actual water temp, that's why I installed a water temp gauge in my gauge pod.
The 2012 does not have a CHT sensor.
 

·
Registered
Joined
·
3,673 Posts
Discussion Starter #13
I posted in another thread about how darn quick the car seems to warm up. How do you know it's playing games with the actual temperature, i.e., not moving after 122F?
Engine (coolant) temperature can be monitored with just about any modern OBD scan tool.
 

·
Registered
Joined
·
211 Posts
my dad and I always say, as long as you note where the gauge usually is, you'll know if something is out of the ordinary... same goes for oil gauges (my stang and his truck have those)
 

·
Registered
Joined
·
418 Posts
...but you probably knew that already.

Did you ever wonder why the temperature gauge gets to the halfway mark so quickly after you start the engine?

The gauge will hit the halfway mark with a coolant temp. of ~50C (122F). As the coolant temp. increases to normal operating temp. (~200F), the gauge won't move.

I don't know what the coolant temp. would have to be for the gauge to read significantly higher, but I imagine that it would start going up quickly when the coolant temp. gets above 210F or so.

The bottom line is that the temperature gauge is highly non-linear by design.
I agree with you,
Did the test yesterday.
Just as you say at 50 deg C the needle goes to just below the halfway mark.
I then drove the car normally for 10 Km with the test screen on the display.
It hovered at about 90 to 93 deg C without any change on the needle.
Once I reached my destination I opened the bonnet and let the engine idle.
The temperature rose to over 110 deg C (still no change on the needle).
The Fan then came on at low speed and the temp dropped to below 100 deg C and the fan stopped. (Aircon was OFF)
In other words everything is happening normally but the needle is not giving any feedback. (This is why we believe that the engine warms up super quickly when in fact it did take a while to get to 90 deg C.)

Can some the Focus Car and Engine Experts please give us your comments on this behaviour.
I've never experience this type of behaviour on the temp gauge of any car.
 

·
Registered
Joined
·
232 Posts
Engine (coolant) temperature can be monitored with just about any modern OBD scan tool.
Ah -- makes sense. Did you use a Scangauge or what? I had the VAG-COM set up for my VW (that worked off my laptop) and I am wondering what folks here use for OBD-II read outs and analysis.
 

·
Registered
Joined
·
724 Posts
my dad and I always say, as long as you note where the gauge usually is, you'll know if something is out of the ordinary... same goes for oil gauges (my stang and his truck have those)
I agree, they aren't designed to be accurate, just show a relative change.
 

·
Registered
Joined
·
772 Posts
It's basically a dummy gauge with 3 positions -- cold, normal, hot

Watching it with my scangauge, it starts rising when the actual engine temp hits 100 degrees and is in the middle "normal" range by 130 degrees. Not enough to get heat out of the vents at that point. It stays in the middle position all the way to 218 degrees. My car has not been over 218 degrees so I don't know what temperature it starts heading toward the hot mark. Another example of programming that's different from other Ford vehicles.
 

·
Registered
Joined
·
418 Posts
It's basically a dummy gauge with 3 positions -- cold, normal, hot

Watching it with my scangauge, it starts rising when the actual engine temp hits 100 degrees and is in the middle "normal" range by 130 degrees. Not enough to get heat out of the vents at that point. It stays in the middle position all the way to 218 degrees. My car has not been over 218 degrees so I don't know what temperature it starts heading toward the hot mark. Another example of programming that's different from other Ford vehicles.
I suppose that it wil only show over the middle position if we actually get an overheat. ??
 
1 - 20 of 29 Posts
Top