Open Loop vs. Closed Loop

[<jbennett@xxxxxxx>]

Typically three things have to happen for the computer to function in 
closed loop mode:

1. O2 sensor must reach about 600 degrees F
2. CTS (Coolant Temperature Sensor) must reach about 190 degrees F
3. A timer must go off.




----- Original Message -----
From: "D. Dardalis" <dardal@xxxxxxxxxxxxxxx>
Date: Thursday, January 24, 2002 4:02 pm
Subject: Re: IML: O2 sensor readings, DB

> At 03:23 PM 1/24/2002 -0500, you wrote:
> >What prompts the computer to
> >switch from open loop to closed loop?  Does it stay in open loop
> >until it receives signals from the O2 sensor or is it prompted by
> >some other input that the engine is warm enough to run in closed
> >loop operation?
> My be I should let DB answer that, but I think that the output of 
> the O2 
> sensor will
> "tell" the computer if its ready to function or not.  But even if 
> the car 
> cannot run on closed loop, there usually are some "limp home" 
> modes that 
> allow the engine to run reasonably well, even though emissions 
> suffer.  Remember, the main reason for the engine to run in closed 
> loop is 
> to keep the catalyst happy (which requires a very accurate control 
> of AF 
> ratio)... D^2
> 
> 
>