Possible to run MAF/SD Tune
Originally Posted by Blackbird
Interesting thread.
I have been running Maf with my 2bar for months now.
I set the MAF to fail at 7000hz (according to my logging this is the point where my car crosses over to boost) and then the 2bar takes it from there.
As for the MAF not renabling after the first time I go into boost, thats what I find interesting. I guess I could do an experiment to see but this whole time I sure thought the MAF was working. The car certainly behaves differently than when I tried to do 100% SD. It's alot more consistant in the non boost areas.
I have been running Maf with my 2bar for months now.
I set the MAF to fail at 7000hz (according to my logging this is the point where my car crosses over to boost) and then the 2bar takes it from there.
As for the MAF not renabling after the first time I go into boost, thats what I find interesting. I guess I could do an experiment to see but this whole time I sure thought the MAF was working. The car certainly behaves differently than when I tried to do 100% SD. It's alot more consistant in the non boost areas.
Base Condition: Stock OS, 1 Bar Sensor
- The car runs off of the MAF/VE tables until the end of the VE table (i.e. 105 )Kpa
- Once the PCM reaches that point it goes into SD where fueling is controlled by PE
New Condition: Add EFILive COS 3 (2/3 Bar) and 2 Bar Map Sensor
- The car runs off of the MAF/VE tables until the end of the VE table (i.e. 105 )Kpa, then moves to the Boost VE tables/Boost Timing Tables where it controls fueling up to the MAP sensor limit (i.e. 210Kpa for 2 bar)
- Once the PCM reaches the max (per 2 bar or 3 bar sensor), it then goes into PE.
Is this an accurate depiction of how the referenced tables interact?
No, that is incorrect.
Base Condition: Stock OS, 1 Bar Sensor
The ECM uses the MAF during steady state driving (cruising on the highway at a steady speed) and references the VE Table for fast throttle transitions. Once the Engine is past 4000 rpms on a WOT run, the MAF is in complete control of fueling. The PE Table only changes the commanded AFR from 14.62 (for F-Bodies) and adds more required fuel. This is based on the Stoich value divided by the PE Value and you get the commanded AFR (14.62/1.125 = 13.0 AFR). Typically N/A application will not reach the end of the MAF Table (~12500), as most engine will see upto 10250. Now with Boost, once you hit past the MAF Fail mode (most are 12000 or 13500), the ECM will ingonre the MAF input because it suspects the MAF is reporting erroneous data, and will go off the last VE Table cells. It will not re-activate the MAF until it can perform a sanity check on it, which is at start up only. Much like when an O2 sensor fails, the ECM will not bringing it back to correct fueling, or even constantly check if it works again. Once it fails it is done with that data stream and is ingored until the car can be serviced/scanned by GM or the ECM.
New Condition: Add HPTuners 2/3 Bar and 2/3 Bar Map Sensor
The MAF is taken completely out of the equation and all fueling is done via the VE Table. The VE Table is now expanded from the max value of 105 kPa to 210kPa (2-BAR) or 320kPa (3-BAR). The PE Table is left stock, so incase the boost is blown out prior to the intake, you will get a safe AFR sicne you are running N/A. The Boost Enrichment will kick in only after the MAP (BAP) sensor detects levels beyond atmoshperich (PSI) and will override the PE Table to add mroe fuel.
Base Condition: Stock OS, 1 Bar Sensor
The ECM uses the MAF during steady state driving (cruising on the highway at a steady speed) and references the VE Table for fast throttle transitions. Once the Engine is past 4000 rpms on a WOT run, the MAF is in complete control of fueling. The PE Table only changes the commanded AFR from 14.62 (for F-Bodies) and adds more required fuel. This is based on the Stoich value divided by the PE Value and you get the commanded AFR (14.62/1.125 = 13.0 AFR). Typically N/A application will not reach the end of the MAF Table (~12500), as most engine will see upto 10250. Now with Boost, once you hit past the MAF Fail mode (most are 12000 or 13500), the ECM will ingonre the MAF input because it suspects the MAF is reporting erroneous data, and will go off the last VE Table cells. It will not re-activate the MAF until it can perform a sanity check on it, which is at start up only. Much like when an O2 sensor fails, the ECM will not bringing it back to correct fueling, or even constantly check if it works again. Once it fails it is done with that data stream and is ingored until the car can be serviced/scanned by GM or the ECM.
New Condition: Add HPTuners 2/3 Bar and 2/3 Bar Map Sensor
The MAF is taken completely out of the equation and all fueling is done via the VE Table. The VE Table is now expanded from the max value of 105 kPa to 210kPa (2-BAR) or 320kPa (3-BAR). The PE Table is left stock, so incase the boost is blown out prior to the intake, you will get a safe AFR sicne you are running N/A. The Boost Enrichment will kick in only after the MAP (BAP) sensor detects levels beyond atmoshperich (PSI) and will override the PE Table to add mroe fuel.
TECH Addict
Joined: Nov 2001
Posts: 2,659
Likes: 1
From: Bellevue, Wa
are you sure MAF is taken completely out? pretty sure it's not.
and boost enrichment will come in whenever you tell it to, not just when you hit boost.
as a matter of fact I have mine come in early (90kpa) because I tune on the paraniod side and I figure it will help avoid any lean spikes when going into boost.
and boost enrichment will come in whenever you tell it to, not just when you hit boost.
as a matter of fact I have mine come in early (90kpa) because I tune on the paraniod side and I figure it will help avoid any lean spikes when going into boost.
Originally Posted by slow
why not just use a maf that supports enough airflow, and scale the tables? 
Ryan
Ryan
Originally Posted by 12secSS
It will not re-activate the MAF until it can perform a sanity check on it, which is at start up only. Much like when an O2 sensor fails, the ECM will not bringing it back to correct fueling, or even constantly check if it works again. Once it fails it is done with that data stream and is ingored until the car can be serviced/scanned by GM or the ECM
Originally Posted by 12secSS
No, that is incorrect.
Base Condition: Stock OS, 1 Bar Sensor
The ECM uses the MAF during steady state driving (cruising on the highway at a steady speed) and references the VE Table for fast throttle transitions. Once the Engine is past 4000 rpms on a WOT run, the MAF is in complete control of fueling. The PE Table only changes the commanded AFR from 14.62 (for F-Bodies) and adds more required fuel. This is based on the Stoich value divided by the PE Value and you get the commanded AFR (14.62/1.125 = 13.0 AFR). Typically N/A application will not reach the end of the MAF Table (~12500), as most engine will see upto 10250. Now with Boost, once you hit past the MAF Fail mode (most are 12000 or 13500), the ECM will ingonre the MAF input because it suspects the MAF is reporting erroneous data, and will go off the last VE Table cells. It will not re-activate the MAF until it can perform a sanity check on it, which is at start up only. Much like when an O2 sensor fails, the ECM will not bringing it back to correct fueling, or even constantly check if it works again. Once it fails it is done with that data stream and is ingored until the car can be serviced/scanned by GM or the ECM.
New Condition: Add HPTuners 2/3 Bar and 2/3 Bar Map Sensor
The MAF is taken completely out of the equation and all fueling is done via the VE Table. The VE Table is now expanded from the max value of 105 kPa to 210kPa (2-BAR) or 320kPa (3-BAR). The PE Table is left stock, so incase the boost is blown out prior to the intake, you will get a safe AFR sicne you are running N/A. The Boost Enrichment will kick in only after the MAP (BAP) sensor detects levels beyond atmoshperich (PSI) and will override the PE Table to add mroe fuel.
Base Condition: Stock OS, 1 Bar Sensor
The ECM uses the MAF during steady state driving (cruising on the highway at a steady speed) and references the VE Table for fast throttle transitions. Once the Engine is past 4000 rpms on a WOT run, the MAF is in complete control of fueling. The PE Table only changes the commanded AFR from 14.62 (for F-Bodies) and adds more required fuel. This is based on the Stoich value divided by the PE Value and you get the commanded AFR (14.62/1.125 = 13.0 AFR). Typically N/A application will not reach the end of the MAF Table (~12500), as most engine will see upto 10250. Now with Boost, once you hit past the MAF Fail mode (most are 12000 or 13500), the ECM will ingonre the MAF input because it suspects the MAF is reporting erroneous data, and will go off the last VE Table cells. It will not re-activate the MAF until it can perform a sanity check on it, which is at start up only. Much like when an O2 sensor fails, the ECM will not bringing it back to correct fueling, or even constantly check if it works again. Once it fails it is done with that data stream and is ingored until the car can be serviced/scanned by GM or the ECM.
New Condition: Add HPTuners 2/3 Bar and 2/3 Bar Map Sensor
The MAF is taken completely out of the equation and all fueling is done via the VE Table. The VE Table is now expanded from the max value of 105 kPa to 210kPa (2-BAR) or 320kPa (3-BAR). The PE Table is left stock, so incase the boost is blown out prior to the intake, you will get a safe AFR sicne you are running N/A. The Boost Enrichment will kick in only after the MAP (BAP) sensor detects levels beyond atmoshperich (PSI) and will override the PE Table to add mroe fuel.
Btw, I am learning a ton here...thanks for all those that are responding
Last edited by Earl H; May 9, 2007 at 11:57 AM.
Originally Posted by Blackbird
are you sure MAF is taken completely out? pretty sure it's not.
and boost enrichment will come in whenever you tell it to, not just when you hit boost.
as a matter of fact I have mine come in early (90kpa) because I tune on the paraniod side and I figure it will help avoid any lean spikes when going into boost.
and boost enrichment will come in whenever you tell it to, not just when you hit boost.
as a matter of fact I have mine come in early (90kpa) because I tune on the paraniod side and I figure it will help avoid any lean spikes when going into boost.
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Originally Posted by Blackbird
are you sure MAF is taken completely out? pretty sure it's not.
Originally Posted by Blackbird
and boost enrichment will come in whenever you tell it to, not just when you hit boost.
Originally Posted by Blackbird
as a matter of fact I have mine come in early (90kpa) because I tune on the paraniod side and I figure it will help avoid any lean spikes when going into boost.
Originally Posted by Earl H
I'm confused...I'm running a TT on a LSx based motor. I routinely max out the MAF (Limit set at 15,500MHZ vs. actual limit ~ 12,000MHz or so) under boost. Doesn't the MAF re-activate once I have dropped below 12,000(seeing as how it never reaches 15,500). Or does it never technically reach its set limit because it cant actually go over the actual limit of the MAF?
Also, what conditions (i.e. situations and tables) cause PE to activate?
Btw, I am learning a ton here...thanks for all those that are responding
What condition triggers the PE table then?
Also, what conditions (i.e. situations and tables) cause PE to activate?
Btw, I am learning a ton here...thanks for all those that are responding
What condition triggers the PE table then?
PE Enablers are (top three are most common):
MAP
TPS
RPM
Torque
Time
Originally Posted by dewmanshu
So..wtf is going on that one person can(seems to) run maf/2bar combo and another can't. Custom OS differences? Only certain years? and which is it, start up or scanned and cleared. LOL just j/k'ing with ya.
It could be based on the alignment of the stars too. 
Originally Posted by Blackbird
Interesting thread.
I have been running Maf with my 2bar for months now.
I set the MAF to fail at 7000hz (according to my logging this is the point where my car crosses over to boost) and then the 2bar takes it from there.
As for the MAF not renabling after the first time I go into boost, thats what I find interesting. I guess I could do an experiment to see but this whole time I sure thought the MAF was working. The car certainly behaves differently than when I tried to do 100% SD. It's alot more consistant in the non boost areas.
I have been running Maf with my 2bar for months now.
I set the MAF to fail at 7000hz (according to my logging this is the point where my car crosses over to boost) and then the 2bar takes it from there.
As for the MAF not renabling after the first time I go into boost, thats what I find interesting. I guess I could do an experiment to see but this whole time I sure thought the MAF was working. The car certainly behaves differently than when I tried to do 100% SD. It's alot more consistant in the non boost areas.
Originally Posted by 12secSS
What is happening with your setup is that the ECM is not seeing more then 12,000MHz and it is coded to recognize a failure above 15,500MHz ... so it is not failing the MAF, it is going off of the last cell in the MAF table (possibly 512g/sec) to calculate the fueling requirements. This is how some hackers will tune, they will then readjust either the IFR table or hack up the PE table to bring the fuel back in line.
TECH Addict
Joined: Nov 2001
Posts: 2,659
Likes: 1
From: Bellevue, Wa
12 - thanks for the fuel transient tip. I am far from a superstar tuner, hadn't looked into using that.
Thinking about this more you all could be right, I have blown the coupler off my car and my buddies car I tuned this way and the car still ran fine, if maf was enabled the car should have freaked out no?
Maybe I will try that today. I can unbolt my coupler and pull it off a smidge like it did when it popped off and then try to start the car. If it runs like crap then it must be that my car goes 100% SD after the first time I hit boost and that explains how I drove 20 miles home just fine. Though if it still runs fine (IE the leak isn't big enough to freak the car out) then I would still be unsure if it renables or not.
Thinking about this more you all could be right, I have blown the coupler off my car and my buddies car I tuned this way and the car still ran fine, if maf was enabled the car should have freaked out no?
Maybe I will try that today. I can unbolt my coupler and pull it off a smidge like it did when it popped off and then try to start the car. If it runs like crap then it must be that my car goes 100% SD after the first time I hit boost and that explains how I drove 20 miles home just fine. Though if it still runs fine (IE the leak isn't big enough to freak the car out) then I would still be unsure if it renables or not.
Originally Posted by Blackbird
12 - thanks for the fuel transient tip. I am far from a superstar tuner, hadn't looked into using that.
Thinking about this more you all could be right, I have blown the coupler off my car and my buddies car I tuned this way and the car still ran fine, if maf was enabled the car should have freaked out no?
Maybe I will try that today. I can unbolt my coupler and pull it off a smidge like it did when it popped off and then try to start the car. If it runs like crap then it must be that my car goes 100% SD after the first time I hit boost and that explains how I drove 20 miles home just fine. Though if it still runs fine (IE the leak isn't big enough to freak the car out) then I would still be unsure if it renables or not.
Thinking about this more you all could be right, I have blown the coupler off my car and my buddies car I tuned this way and the car still ran fine, if maf was enabled the car should have freaked out no?
Maybe I will try that today. I can unbolt my coupler and pull it off a smidge like it did when it popped off and then try to start the car. If it runs like crap then it must be that my car goes 100% SD after the first time I hit boost and that explains how I drove 20 miles home just fine. Though if it still runs fine (IE the leak isn't big enough to freak the car out) then I would still be unsure if it renables or not.
