OL SD... break it down big bird-barney style for me
10-13-2006, 02:14 PM
#1
OL SD... break it down big bird-barney style for me When i have my car in open loop and speed density mode, does this mean my computer is determining spark and fuel based only on the ve and spark table values? and if i set my PE to 1.0 in evey cell, does this cause WOT fueling be determined bases on the VE table values only? my idea is to try and eliminate as much of the computer's control over spark and fuel as possible. If theres a better way to do this, or if you have any suggestions, let me know! thanks.
10-13-2006, 02:37 PM
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You don't want to eliminate PE. As foff said, OLSD ignores the MAF and oxygen sensors. Your AFR is determined by the values in the open loop fueling table, VE table, PE table and any modifiers that may be activated (ie - PE based on ECT). Think of the VE table as the base. If there are no other interfering factors, the numbers within this table should produce the commanded AFR listed in the open loop fueling table. If they don't, you need to increase/decrease them until they do. PE is a straight adder. If you have the base (VE) right, PE will be right. But, don't turn it off. Running lean at WOT is definitely not recommended.
Spark is determined by your low octane table and base spark tables when the MAF is off. It also has tweaker tables that will command different spark values if IAT's or ECT's are in the right range.
All of this is in the stickies. It's a lot of reading, but you have to do it if you want to learn. There's no quick "learn how to tune pill" you can take before you go to bed and wake up the next morning knowing everything. If there was, I'd be selling 'em at $200 a pop.
Spark is determined by your low octane table and base spark tables when the MAF is off. It also has tweaker tables that will command different spark values if IAT's or ECT's are in the right range.
All of this is in the stickies. It's a lot of reading, but you have to do it if you want to learn. There's no quick "learn how to tune pill" you can take before you go to bed and wake up the next morning knowing everything. If there was, I'd be selling 'em at $200 a pop.
10-13-2006, 02:40 PM
#4
Today's lesson is brought to you by the number: pi
Open Loop - the narrow band oxygen sensors (a.k.a. O2 sensors) are not providing feedback to the PCM. Narrow band oxygen sensors (0-1 Volts) are only accurate at the stoichiometric A/F ratio (14.7-ish parts air to 1 part gasoline for gasoline). They just switch back and forth between 0-1 Volts, and the computer can figure out a correction to the fueling based on that frequency. I like to think of the PCM as a black box - i.e. information goes in, some crazy **** happens in there, and information comes out. Narrow band O2 sensors require heat to work correctly, so keeping them close to the exiting exhaust stream of the engine is essential. Enter long tube headers in to this equation. You've now just introduced cooler exhaust gases to the O2 sensor, as it is now further downstream from the engine (and thus illegal by Federal Law). Not as much heat = not as efficient, and the sensor will now have a shorter life as its heater element tries to make up for the heat it is now not seeing. Eventually, the heater element will start to cough and wheeze, and your fuel trims will get all sorts of whacked out because of the "crazy ****" (calculations) that is going on inside the PCM. You can adjust the PCM to compensate for this, but there is little documented evidence of a sure-fire way to do it.
People like me get tired of lazy oxygen sensors, and instead say "screw you, I'm going home." Or something like that. Since I tuned my car with a wideband oxygen sensor, and that wideband sensor is accurate over a wider voltage range (0-5V), I just decided to use that as my truth source. Only the PCM doesn't (and can't) know this. It just knows it now has no feedback. So I tell it what is coming out of the engine by manipulating the VE table (which is a fueling calculation - a.k.a. "crazy ****").
The two big tuning programs do this by incorporating the wideband data into the data stream coming from the PCM - the PCM can tell you what's commanded, the wideband tells you what it saw, and you can now come up with a percentage difference between the two. Hopefully you can trust your O2 sensor. A good sanity check might be to "read" spark plugs as well. Sounds like alchemy to me, but has been done for a long time.
Speed Density - now all you are doing is ignoring the readings from the Mass Air Flow Sensor. The MAF sensor uses a heated wire element, and is a black box in and of itself. As the air goes over the heated wires, the wires cool, so the sensor has to provide more heat to the wires (it wants to maintain a constant heat). More air over the wires = more cooling = more heat to the wires is needed. The MAF outputs its heat added as a frequency that the PCM can understand in it's "crazy" world. It sees the frequency, looks up said frequency in a table, and realizes that "hey, I have about this much air coming in." The trouble lies in its calibration. The MAF table only tells the truth if it was told the truth to begin with. MAF sensors can detect the air going across the wires, but it doesn't care which way the air is flowing. You'll hear people use terms like "reversion", which is essentially where the flow reverses (yes, it can happen, and is more prevalent on a cammed car).
Speed Density is nothing more than a backup way of calculating the air mass based on other sensors (Inlet Air Temp and Manifold Absolute Pressure are the big players). Again, nothing more than a set of values it looks up. I run my car this way because it is just one less thing to tune (no MAF = no worries about calibrating its table).
As for Power Enrichment, you should actually set it to where you want it. If you want an A/F ratio of 13.0:1 at 2400 RPMs, you should set the PE table to 1.13 (14.63 divided by 1.13 gives you 13.0-ish for those that don't know where that comes from) in that particular cell. Then, when you tune your VE table, and you hit all the necessary conditions to enter PE mode (essentially WOT for all intents and purposes), you will now command something other than stoich (which is needed at WOT). You'll quickly realize that the 95-100 kPa region of the VE table is almost exclusively used at WOT, so those are the only cells that will be adjusted. The reason you don't want to set the PE table to zero is because of how the tuning software is set up - remember, it is looking at commanded AFR versus actual. If you are commanding 14.63, then your percentage difference will be as a result of that. If you are commanding 13.0, your percentage difference will be based on that value.
Is that Big Bird enough?
Open Loop - the narrow band oxygen sensors (a.k.a. O2 sensors) are not providing feedback to the PCM. Narrow band oxygen sensors (0-1 Volts) are only accurate at the stoichiometric A/F ratio (14.7-ish parts air to 1 part gasoline for gasoline). They just switch back and forth between 0-1 Volts, and the computer can figure out a correction to the fueling based on that frequency. I like to think of the PCM as a black box - i.e. information goes in, some crazy **** happens in there, and information comes out. Narrow band O2 sensors require heat to work correctly, so keeping them close to the exiting exhaust stream of the engine is essential. Enter long tube headers in to this equation. You've now just introduced cooler exhaust gases to the O2 sensor, as it is now further downstream from the engine (and thus illegal by Federal Law). Not as much heat = not as efficient, and the sensor will now have a shorter life as its heater element tries to make up for the heat it is now not seeing. Eventually, the heater element will start to cough and wheeze, and your fuel trims will get all sorts of whacked out because of the "crazy ****" (calculations) that is going on inside the PCM. You can adjust the PCM to compensate for this, but there is little documented evidence of a sure-fire way to do it.
People like me get tired of lazy oxygen sensors, and instead say "screw you, I'm going home." Or something like that. Since I tuned my car with a wideband oxygen sensor, and that wideband sensor is accurate over a wider voltage range (0-5V), I just decided to use that as my truth source. Only the PCM doesn't (and can't) know this. It just knows it now has no feedback. So I tell it what is coming out of the engine by manipulating the VE table (which is a fueling calculation - a.k.a. "crazy ****").
The two big tuning programs do this by incorporating the wideband data into the data stream coming from the PCM - the PCM can tell you what's commanded, the wideband tells you what it saw, and you can now come up with a percentage difference between the two. Hopefully you can trust your O2 sensor. A good sanity check might be to "read" spark plugs as well. Sounds like alchemy to me, but has been done for a long time.
Speed Density - now all you are doing is ignoring the readings from the Mass Air Flow Sensor. The MAF sensor uses a heated wire element, and is a black box in and of itself. As the air goes over the heated wires, the wires cool, so the sensor has to provide more heat to the wires (it wants to maintain a constant heat). More air over the wires = more cooling = more heat to the wires is needed. The MAF outputs its heat added as a frequency that the PCM can understand in it's "crazy" world. It sees the frequency, looks up said frequency in a table, and realizes that "hey, I have about this much air coming in." The trouble lies in its calibration. The MAF table only tells the truth if it was told the truth to begin with. MAF sensors can detect the air going across the wires, but it doesn't care which way the air is flowing. You'll hear people use terms like "reversion", which is essentially where the flow reverses (yes, it can happen, and is more prevalent on a cammed car).
Speed Density is nothing more than a backup way of calculating the air mass based on other sensors (Inlet Air Temp and Manifold Absolute Pressure are the big players). Again, nothing more than a set of values it looks up. I run my car this way because it is just one less thing to tune (no MAF = no worries about calibrating its table).
As for Power Enrichment, you should actually set it to where you want it. If you want an A/F ratio of 13.0:1 at 2400 RPMs, you should set the PE table to 1.13 (14.63 divided by 1.13 gives you 13.0-ish for those that don't know where that comes from) in that particular cell. Then, when you tune your VE table, and you hit all the necessary conditions to enter PE mode (essentially WOT for all intents and purposes), you will now command something other than stoich (which is needed at WOT). You'll quickly realize that the 95-100 kPa region of the VE table is almost exclusively used at WOT, so those are the only cells that will be adjusted. The reason you don't want to set the PE table to zero is because of how the tuning software is set up - remember, it is looking at commanded AFR versus actual. If you are commanding 14.63, then your percentage difference will be as a result of that. If you are commanding 13.0, your percentage difference will be based on that value.
Is that Big Bird enough?
10-13-2006, 03:08 PM
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Originally Posted by SSpdDmon
There's no quick "learn how to tune pill" you can take before you go to bed and wake up the next morning knowing everything. If there was, I'd be selling 'em at $200 a pop.
Back on topic you can eliminate the pe table by setting it to 1.o the open loop comanded afr table will do the job just a little more difficult that way cause you have to do hard acceleration at part throttle as well. Pe is not just wot its based on throttle percentage and rpm as well.
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10-13-2006, 04:09 PM
#9
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Originally Posted by MeentSS02
Today's lesson is brought to you by the number: pi
Is that Big Bird enough?
Is that Big Bird enough?
Jim
Guess I'm only a commedian in my own head 
10-13-2006, 08:07 PM
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Originally Posted by MeentSS02
Today's lesson is brought to you by the number: pi
Open Loop - the narrow band oxygen sensors (a.k.a. O2 sensors) are not providing feedback to the PCM. Narrow band oxygen sensors (0-1 Volts) are only accurate at the stoichiometric A/F ratio (14.7-ish parts air to 1 part gasoline for gasoline). They just switch back and forth between 0-1 Volts, and the computer can figure out a correction to the fueling based on that frequency. I like to think of the PCM as a black box - i.e. information goes in, some crazy **** happens in there, and information comes out. Narrow band O2 sensors require heat to work correctly, so keeping them close to the exiting exhaust stream of the engine is essential. Enter long tube headers in to this equation. You've now just introduced cooler exhaust gases to the O2 sensor, as it is now further downstream from the engine (and thus illegal by Federal Law). Not as much heat = not as efficient, and the sensor will now have a shorter life as its heater element tries to make up for the heat it is now not seeing. Eventually, the heater element will start to cough and wheeze, and your fuel trims will get all sorts of whacked out because of the "crazy ****" (calculations) that is going on inside the PCM. You can adjust the PCM to compensate for this, but there is little documented evidence of a sure-fire way to do it.
People like me get tired of lazy oxygen sensors, and instead say "screw you, I'm going home." Or something like that. Since I tuned my car with a wideband oxygen sensor, and that wideband sensor is accurate over a wider voltage range (0-5V), I just decided to use that as my truth source. Only the PCM doesn't (and can't) know this. It just knows it now has no feedback. So I tell it what is coming out of the engine by manipulating the VE table (which is a fueling calculation - a.k.a. "crazy ****").
The two big tuning programs do this by incorporating the wideband data into the data stream coming from the PCM - the PCM can tell you what's commanded, the wideband tells you what it saw, and you can now come up with a percentage difference between the two. Hopefully you can trust your O2 sensor. A good sanity check might be to "read" spark plugs as well. Sounds like alchemy to me, but has been done for a long time.
Speed Density - now all you are doing is ignoring the readings from the Mass Air Flow Sensor. The MAF sensor uses a heated wire element, and is a black box in and of itself. As the air goes over the heated wires, the wires cool, so the sensor has to provide more heat to the wires (it wants to maintain a constant heat). More air over the wires = more cooling = more heat to the wires is needed. The MAF outputs its heat added as a frequency that the PCM can understand in it's "crazy" world. It sees the frequency, looks up said frequency in a table, and realizes that "hey, I have about this much air coming in." The trouble lies in its calibration. The MAF table only tells the truth if it was told the truth to begin with. MAF sensors can detect the air going across the wires, but it doesn't care which way the air is flowing. You'll hear people use terms like "reversion", which is essentially where the flow reverses (yes, it can happen, and is more prevalent on a cammed car).
Speed Density is nothing more than a backup way of calculating the air mass based on other sensors (Inlet Air Temp and Manifold Absolute Pressure are the big players). Again, nothing more than a set of values it looks up. I run my car this way because it is just one less thing to tune (no MAF = no worries about calibrating its table).
As for Power Enrichment, you should actually set it to where you want it. If you want an A/F ratio of 13.0:1 at 2400 RPMs, you should set the PE table to 1.13 (14.63 divided by 1.13 gives you 13.0-ish for those that don't know where that comes from) in that particular cell. Then, when you tune your VE table, and you hit all the necessary conditions to enter PE mode (essentially WOT for all intents and purposes), you will now command something other than stoich (which is needed at WOT). You'll quickly realize that the 95-100 kPa region of the VE table is almost exclusively used at WOT, so those are the only cells that will be adjusted. The reason you don't want to set the PE table to zero is because of how the tuning software is set up - remember, it is looking at commanded AFR versus actual. If you are commanding 14.63, then your percentage difference will be as a result of that. If you are commanding 13.0, your percentage difference will be based on that value.
Is that Big Bird enough?
Open Loop - the narrow band oxygen sensors (a.k.a. O2 sensors) are not providing feedback to the PCM. Narrow band oxygen sensors (0-1 Volts) are only accurate at the stoichiometric A/F ratio (14.7-ish parts air to 1 part gasoline for gasoline). They just switch back and forth between 0-1 Volts, and the computer can figure out a correction to the fueling based on that frequency. I like to think of the PCM as a black box - i.e. information goes in, some crazy **** happens in there, and information comes out. Narrow band O2 sensors require heat to work correctly, so keeping them close to the exiting exhaust stream of the engine is essential. Enter long tube headers in to this equation. You've now just introduced cooler exhaust gases to the O2 sensor, as it is now further downstream from the engine (and thus illegal by Federal Law). Not as much heat = not as efficient, and the sensor will now have a shorter life as its heater element tries to make up for the heat it is now not seeing. Eventually, the heater element will start to cough and wheeze, and your fuel trims will get all sorts of whacked out because of the "crazy ****" (calculations) that is going on inside the PCM. You can adjust the PCM to compensate for this, but there is little documented evidence of a sure-fire way to do it.
People like me get tired of lazy oxygen sensors, and instead say "screw you, I'm going home." Or something like that. Since I tuned my car with a wideband oxygen sensor, and that wideband sensor is accurate over a wider voltage range (0-5V), I just decided to use that as my truth source. Only the PCM doesn't (and can't) know this. It just knows it now has no feedback. So I tell it what is coming out of the engine by manipulating the VE table (which is a fueling calculation - a.k.a. "crazy ****").
The two big tuning programs do this by incorporating the wideband data into the data stream coming from the PCM - the PCM can tell you what's commanded, the wideband tells you what it saw, and you can now come up with a percentage difference between the two. Hopefully you can trust your O2 sensor. A good sanity check might be to "read" spark plugs as well. Sounds like alchemy to me, but has been done for a long time.
Speed Density - now all you are doing is ignoring the readings from the Mass Air Flow Sensor. The MAF sensor uses a heated wire element, and is a black box in and of itself. As the air goes over the heated wires, the wires cool, so the sensor has to provide more heat to the wires (it wants to maintain a constant heat). More air over the wires = more cooling = more heat to the wires is needed. The MAF outputs its heat added as a frequency that the PCM can understand in it's "crazy" world. It sees the frequency, looks up said frequency in a table, and realizes that "hey, I have about this much air coming in." The trouble lies in its calibration. The MAF table only tells the truth if it was told the truth to begin with. MAF sensors can detect the air going across the wires, but it doesn't care which way the air is flowing. You'll hear people use terms like "reversion", which is essentially where the flow reverses (yes, it can happen, and is more prevalent on a cammed car).
Speed Density is nothing more than a backup way of calculating the air mass based on other sensors (Inlet Air Temp and Manifold Absolute Pressure are the big players). Again, nothing more than a set of values it looks up. I run my car this way because it is just one less thing to tune (no MAF = no worries about calibrating its table).
As for Power Enrichment, you should actually set it to where you want it. If you want an A/F ratio of 13.0:1 at 2400 RPMs, you should set the PE table to 1.13 (14.63 divided by 1.13 gives you 13.0-ish for those that don't know where that comes from) in that particular cell. Then, when you tune your VE table, and you hit all the necessary conditions to enter PE mode (essentially WOT for all intents and purposes), you will now command something other than stoich (which is needed at WOT). You'll quickly realize that the 95-100 kPa region of the VE table is almost exclusively used at WOT, so those are the only cells that will be adjusted. The reason you don't want to set the PE table to zero is because of how the tuning software is set up - remember, it is looking at commanded AFR versus actual. If you are commanding 14.63, then your percentage difference will be as a result of that. If you are commanding 13.0, your percentage difference will be based on that value.
Is that Big Bird enough?
