Need some datalog help deciphering
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From: Delcambre, La
Need some datalog help deciphering
I got a new tune from Sal, we've been emailing back and forth with data and tunes. I know he is a busy man so instead of wasting his time with these kinds of questions I figured one of you guys might beable to help me.
He typed "I also want you to log short term fuel trims and the open loop flag this time too, so we can see just how far off the closed loop fuel is at idle and part throttle and such. I have shut the adaptive fuel off this time, so it's just going to have short term fuel correction, and no long term. So you'll probably have to check it soon, because if it's still far off, it will throw codes sooner."
I assume when I record I pick both short term fuel trims? But what is open loop flag? and how is that going to help predict closed loop? Do I datalog at idle or is know this at WOT going to help figure out what idle/part throttle would be?
I plan on datalogging as soon as the weather clears but it helps when I understand exactly what he's talking about and wants so I get him the right info the first time.
He typed "I also want you to log short term fuel trims and the open loop flag this time too, so we can see just how far off the closed loop fuel is at idle and part throttle and such. I have shut the adaptive fuel off this time, so it's just going to have short term fuel correction, and no long term. So you'll probably have to check it soon, because if it's still far off, it will throw codes sooner."
I assume when I record I pick both short term fuel trims? But what is open loop flag? and how is that going to help predict closed loop? Do I datalog at idle or is know this at WOT going to help figure out what idle/part throttle would be?
I plan on datalogging as soon as the weather clears but it helps when I understand exactly what he's talking about and wants so I get him the right info the first time.
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Joined: Feb 2004
Posts: 10,390
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Originally Posted by brahmus
I got a new tune from Sal, we've been emailing back and forth with data and tunes. I know he is a busy man so instead of wasting his time with these kinds of questions I figured one of you guys might beable to help me.
He typed "I also want you to log short term fuel trims and the open loop flag this time too, so we can see just how far off the closed loop fuel is at idle and part throttle and such. I have shut the adaptive fuel off this time, so it's just going to have short term fuel correction, and no long term. So you'll probably have to check it soon, because if it's still far off, it will throw codes sooner."
I assume when I record I pick both short term fuel trims? But what is open loop flag? and how is that going to help predict closed loop? Do I datalog at idle or is know this at WOT going to help figure out what idle/part throttle would be?
I plan on datalogging as soon as the weather clears but it helps when I understand exactly what he's talking about and wants so I get him the right info the first time.
He typed "I also want you to log short term fuel trims and the open loop flag this time too, so we can see just how far off the closed loop fuel is at idle and part throttle and such. I have shut the adaptive fuel off this time, so it's just going to have short term fuel correction, and no long term. So you'll probably have to check it soon, because if it's still far off, it will throw codes sooner."
I assume when I record I pick both short term fuel trims? But what is open loop flag? and how is that going to help predict closed loop? Do I datalog at idle or is know this at WOT going to help figure out what idle/part throttle would be?
I plan on datalogging as soon as the weather clears but it helps when I understand exactly what he's talking about and wants so I get him the right info the first time.
Yup.
Choose both STFT PID's.
The PID for Open Loop Flag is a binary value - for me it returned a 1 or a 0; 1 = Open loop, 0= closed Loop.
[PCM goes into Open loop operation at high load/WOT - PCM commands A/F's from stored tables and the MAF TF; whereas in Closed Loop - PCM is usng front O2 feedback and runs stioic ( 14.64:1).]
STFT's can be done in rpm steps - starting from idle, through part-throttle, truck stationary.
Obviously if he wants to see STFT's @ WOT - you gotta do a run/pull under load.
Normally you don't care about those in open loop @ WOT - but I think those values mean something else under those conditions....?
Good luck.
Bubba
Last edited by MGDfan; Aug 17, 2007 at 02:57 PM.
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Joined: Oct 2005
Posts: 541
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From: Odenton MD
more Info
Hi.
Closed loop: A/F's determined by feedback from the front O2's.
Open loop: A/F's determined by programmed fuel tables in the PCM.
"Closed loop" is derived from control systems terminology & refers to any system that actively & continuously self-corrects to a known state via a feedback loop - in this case it's Stioic ( 14.x:1) & the feedback is provided by the O2 voltages.
The inability to go Open loop prevents a vehicle from producing it's rated power
Hi.
Closed loop: A/F's determined by feedback from the front O2's.
Open loop: A/F's determined by programmed fuel tables in the PCM.
"Closed loop" is derived from control systems terminology & refers to any system that actively & continuously self-corrects to a known state via a feedback loop - in this case it's Stioic ( 14.x:1) & the feedback is provided by the O2 voltages.
The inability to go Open loop prevents a vehicle from producing it's rated power
Bubba
