Open loop, closed loop temperature?

2000tjguy said:
Again the overheating didn’t happen in Colorado but that’s neither here nor there and the question asked was at what temp these go into to closed loop.
Mainly just asking a simple question cause I haven’t seen a solid answer to that question but I guess this has to spin to everything I’m doing is wrong 🤷🏻
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I guess where I got confused is that the system goes from open to closed all the time depending on throttle & other factors. Or that is my understanding on how it works from watching my engine.

I'm sorry I haven't said you were doing anything wrong I'm just trying to understand. And if I could help.
 
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@2000tjguy

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https://www.tuneruniversity.com/blo...em with a low,wear on the engine's internals.
 
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Wildman said:
I guess where I got confused is that the system goes from open to closed all the time depending on throttle & other factors. Or that is my understanding on how it works from watching my engine.

I'm sorry I haven't said you were doing anything wrong I'm just trying to understand. And if I could help.
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Maybe the way I was thinking was wrong I was under the impression that it will never see closed loop without the coolant temp seeing a certain degrees which I never did see a solid answer on at what temp that was.
Honestly it runs fine now I was just seeing if anything would change by going to a touch higher stat.
I didn’t mean you were calling me wrong but other people in this thread have made that apparent.
 
TonyArms said:
So its about fuel mixture ? Default vs control by pcm ?
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Open loop is when the pcm ( Engine computer) is using stored parameters (injector pulse width, ignition timing) to control the engine running. When the engine goes into closed loop the o2 sensors and other sensors are used to control the ignition and fuel system.
 
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2000tjguy said:
Maybe the way I was thinking was wrong I was under the impression that it will never see closed loop without the coolant temp seeing a certain degrees which I never did see a solid answer on at what temp that was.
Honestly it runs fine now I was just seeing if anything would change by going to a touch higher stat.
I didn’t mean you were calling me wrong but other people in this thread have made that apparent.
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This is where I've always understood why you needed to run the factory determined t-stat unless you have lowered the set point in your tune.

Closed loop operation occurs when the oxygen sensors reach their normal operating temp and the coolant temp has reached a predetermined setpoint along with some other things. In closed loop the PCM uses the oxygen sensors as direct inputs to control the AFR, or Air Fuel Ration. The varying voltage produced by the oxygen sensors gives the PCM that data so it can give the engine the fuel that it needs based on the current operating condition.
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2000tjguy said:
There is a difference in running no stat and a lower temp stat… if a 15* change in coolant temp will change the cylinder temp enough to drown the bottom end with gas then we have bigger problems… cat? What’s a cat?
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Won’t happen pcm will correct for coolant temperature
 
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2000tjguy said:
Maybe the way I was thinking was wrong I was under the impression that it will never see closed loop without the coolant temp seeing a certain degrees which I never did see a solid answer on at what temp that was.
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The system will go into short term closed loop once the temp reaches 35 deg.

Long term closed loop requires full operating temperature.
 
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Wildman said:
I guess I am still confused as to why you were wondering when it goes into closed loop or open loop.

A few things I got for searching a little.









So my only argument for running the 195* t-stat is for your engine to be running most efficiently. From everything I've ever understood was that to run a cooler t-stat you needed to adjust your tune to do so.
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All the while i was feeling this was above my pay grade.
 
MikeE024 said:
Does it compensate with less fuel or advanced timing?
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This is the main reason for my question… could I squeak a little more performance out of it by going up in temp a little bit. I’m not sure if the tuning maps can change with temps. On newer vehicles and a lot of people we race with have maps with temp changes.
With older vehicles on stock tuning this my be a waste of time to talk about but who knows.
 
NskLJ said:
Open loop is when the pcm ( Engine computer) is using stored parameters (injector pulse width, ignition timing) to control the engine running. When the engine goes into closed loop the o2 sensors and other sensors are used to control the ignition and fuel system.
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thank you
 
Painfultruth said:
The system will go into short term closed loop once the temp reaches 35 deg.

Long term closed loop requires full operating temperature.
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Makes sense, I wasn’t sure if they the considered full operating temperature at a lower set temperature due to different drive conditions/ driving temperatures.
 
NskLJ said:
Whatever is needed. Pcm strategy is sophisticated to to run an engine in all conditions while maintaining emission, driveability, and power requirements.
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I asked because my original Banks tune dumped more fuel in the cylinder when IATs were high, but the newer tune pulled timing under the same conditions. It's all moot now that my IATs are much lower, but I thought it was interesting to see how Diablo's tunes for Banks handled higher temps.
 
Wildman said:
This is where I've always understood why you needed to run the factory determined t-stat unless you have lowered the set point in your tune.
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Understood but to me it would make sense to have the determined temperature set below the stock stat temperature of 195*.
I have driven many different vehicles in very cold conditions with the coolant temp making big temp swings as the thermostat opens and close which very well could be throwing it back and forth between open and closed loop or closed loop temp could be set lower than the thermostat temp to combat these conditions which could actually mean optimal operating temp is actually lower than the set 195*.
Or I could very well be wrong but I wanted to test it to see even though I doubt I would even be able to notice a difference.
Damn me for being a person who likes to tinker 😂
 
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