What's the difference between closed loop and open
 

I have heard this term alot, and I don't really know what it means, help?

Re: What's the difference between closed loop and open (snoballgsr)
 

From what I know, and keep in mind I am very new to the import scene, closed loop and open loop refer to the fuel mixture/mapping. When you start your car in the morning, the engine is cold and a default fuel mixture is used. When your car warms up, the engine switches to closed loop (I think) and relies on sensor input for all fuel adjustments. So basically, open vs. closed loop refers to how your fuel is being managed.

Re: What's the difference between closed loop and open (JohnnyWash1)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JohnnyWash1 &raquo;</TD></TR><TR><TD CLASS="quote">From what I know, and keep in mind I am very new to the import scene, closed loop and open loop refer to the fuel mixture/mapping. When you start your car in the morning, the engine is cold and a default fuel mixture is used. When your car warms up, the engine switches to closed loop (I think) and relies on sensor input for all fuel adjustments. So basically, open vs. closed loop refers to how your fuel is being managed.</TD></TR></TABLE>

yes you got it in a nut shell

Re: What's the difference between closed loop and open (pornstarSR)
 

Great....thanks for the awnser, but what determines if the engine is warmed up enough.

Oxygen sensors??

Re: What's the difference between closed loop and open (snoballgsr)
 

coolant temp. sensor, o2

Re: What's the difference between closed loop and open (JohnnyWash1)
 

I'm pretty sure you have it backwards. When you start up a car, the engine is in closed loop meaning system IS constantly reading the O2 sensor to adjust mixtures. This is done for emissions and to get the cat converter up to temp as fast as possible.

Most new cars stay in closed loop as long and your at part throttle and/or below a certain rpm.

Under full throttle conditions, the motor goes into open loop where it adds fuel based on pre-determined maps and input from sensors like MAP, TPS, IAT etc.

This is how it worked on my 200o Camaro SS.

Re: What's the difference between closed loop and open (Steve91)
 

JohnnyWash1 is right.

steve91 is incorrect about it at start up. it is all based on when your engine warms up as well as a preset time set by the manufacturer, however steve was correct that when at full throttle most systems will go into open loop and revert back to predetermined fuel maps until the driver steps off the throttle.

All this is changing slowly though because of ever tighter emmissions regulations and the time for open loop to change to closed loop is being made shorter by most manufacturers on their new cars. = better fuel economy and better emmisions