puter help
Thread Starter
Instructor
Joined: Jan 2003
Posts: 139
Likes: 0
From: Tyler TX
puter help
I have a 93 Lt1 corvette. I recently purchased a laptop with diacom software that reads all the senssors and shows me whats goin on. I bought this for when i use nitrous I will be able to tell whats goin on with the fuel mixture to prevent problems. my question is, in this software, it tells you what mode the ecm is running in. For some reason it says closed loop mode, even after the car is warmed up. Can anyone explain why this is :confused:
I know closed loop is for when a car is cold but when its warm it would switch over to open loop mode and act normal. At no point in my testing for about an hour did the ECM switch out of this mode.
I know closed loop is for when a car is cold but when its warm it would switch over to open loop mode and act normal. At no point in my testing for about an hour did the ECM switch out of this mode.
Le Mans Master
Joined: Jul 2001
Posts: 8,181
Likes: 3
From: Santa Maria, CA
Re: puter help (Mini_K)
It's the other way around. After the motor warms up, it should go into closed loop taking readings from your O2 sensors. Upon start up/cold, should be in open loop.
btw, welcome to the forum :cheers:
btw, welcome to the forum :cheers:
Thread Starter
Instructor
Joined: Jan 2003
Posts: 139
Likes: 0
From: Tyler TX
Re: puter help (89 Paul in Cal)
well crap, i had always thought and heard that closed loop mode is for cold starts and open is for when its running. hmmm interesting. thanks for the info :D
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Re: puter help (Mini_K)
well crap, i had always thought and heard that closed loop mode is for cold starts and open is for when its running. hmmm interesting. thanks for the info :D
What I have found is the display is "Open Loop" when the engine is cold and "Closed Loop" after the engine warms up.
However, at Wide Open Throttle, it is well known that the computer is in Open Loop; but, if you look at that parameter at WOT, it still says "Closed Loop."
What you really want to look at for WOT is "Block Learn." After the computer is in "Closed Loop", it will read "Block Learn enabled" when it is really in closed loop and "Block Learn Disabled" at WOT when it is no longer in closed loop.
This gets confusing, so to make it simple, here is how I look at it:
If the parameters are "Closed Loop" and "Block Learn Enabled" the computer is really in closed loop, anything else is open loop.
Some scan-tools show "Block Learn enabled" as "True" or "False." My Tech-1A shows it as "Block Learn Enabled" or "Block Learn Disabled."
Tom Piper
[Modified by Tom Piper, 8:17 AM 2/13/2003]
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: puter help (Tom Piper)
I think these guys have you straightened out now. Just remember that the closed loop is describing the ECM reading the sensors, then making changes to them, hence a closed loop. Open loop the ECM just reads parameters from the chip and runs them, regardless of the sensor readings.
You will not be able to make a *good* evaluation of the fuel/air ratio with the laptop, do to the fact that the stock o2 sensors are not very accurate, unless you calibrate it to a WB02, and even then I would be hesitant, but its better than just going from other peoples advice. You really need to tune AFR at a dyno to be safe.
Good luck :cheers:
You will not be able to make a *good* evaluation of the fuel/air ratio with the laptop, do to the fact that the stock o2 sensors are not very accurate, unless you calibrate it to a WB02, and even then I would be hesitant, but its better than just going from other peoples advice. You really need to tune AFR at a dyno to be safe.
Good luck :cheers:
