No MAF? No problem!
#108
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If this setup reads absolute pressure rather than gauge pressure, it shouldn't matter. At higher altitudes it would read lower pressure and lower altitudes higher pressure and would therefore would calculate the correct airflow. With a blow-through setup altitude could cause a problem, but with full speed density it shouldn't make a difference.
-Paul
-Paul
#109
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i guess in the end it would matter. the air density required to make a certain boost number at a certain altitude is not the same for all altitudes and the air mass being different in each case will cause some problems when going cross country.
how does honda do it? they keep the baro?
how does honda do it? they keep the baro?
#110
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i guess in the end it would matter. the air density required to make a certain boost number at a certain altitude is not the same for all altitudes and the air mass being different in each case will cause some problems when going cross country.
how does honda do it? they keep the baro?
how does honda do it? they keep the baro?
-Paul
#111
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Speed density has to be based on MAP and not gauge pressure. The air density in the manifold is proportional to the absolute pressure and absolute temperature of the air in the manifold. Load will be calculated from that estimated air density and throttle position. A car tuned in load or MAP control will show higher gauge boost readings at higher elevations. The engine will be under the same stress (load) at any altitude though.
I just took a quick look at my Evo IX disassembly. The stock Evo programming uses baro pressure in several different subroutines. I haven't tried to figure out what those subroutines do or what influence baro pressure has on the outcome of those subroutines, but it seems quite reasonable to me that a speed density Evo could run like crap if driven at an altitude different than what it was tuned at.
I just took a quick look at my Evo IX disassembly. The stock Evo programming uses baro pressure in several different subroutines. I haven't tried to figure out what those subroutines do or what influence baro pressure has on the outcome of those subroutines, but it seems quite reasonable to me that a speed density Evo could run like crap if driven at an altitude different than what it was tuned at.
#112
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Speed density has to be based on MAP and not gauge pressure. The air density in the manifold is proportional to the absolute pressure and absolute temperature of the air in the manifold. Load will be calculated from that estimated air density and throttle position. A car tuned in load or MAP control will show higher gauge boost readings at higher elevations. The engine will be under the same stress (load) at any altitude though.
I just took a quick look at my Evo IX disassembly. The stock Evo programming uses baro pressure in several different subroutines. I haven't tried to figure out what those subroutines do or what influence baro pressure has on the outcome of those subroutines, but it seems quite reasonable to me that a speed density Evo could run like crap if driven at an altitude different than what it was tuned at.
I just took a quick look at my Evo IX disassembly. The stock Evo programming uses baro pressure in several different subroutines. I haven't tried to figure out what those subroutines do or what influence baro pressure has on the outcome of those subroutines, but it seems quite reasonable to me that a speed density Evo could run like crap if driven at an altitude different than what it was tuned at.
#113
For what its worth....
In my other car I run a HKS FCon VPRO standalone EMS. We no longer use the stock MAF sensor on that vehicle and it uses its own HKS/Denso MAP and IAT sensors. The HKS FCon has a "altitude compensation table" that allows the VPro to compensate for changes in altitude based on your elevation, so your tune remains the same, if not very close to its original tune regardless of location. Does ECU Flash offer anything like this, if not can it be implemented?
Hope this helps,
George
In my other car I run a HKS FCon VPRO standalone EMS. We no longer use the stock MAF sensor on that vehicle and it uses its own HKS/Denso MAP and IAT sensors. The HKS FCon has a "altitude compensation table" that allows the VPro to compensate for changes in altitude based on your elevation, so your tune remains the same, if not very close to its original tune regardless of location. Does ECU Flash offer anything like this, if not can it be implemented?
Hope this helps,
George
Last edited by XBS; Oct 4, 2007 at 02:17 AM.
#114
The stock ecu has it but I think it must be changed to be scaled against MAP rather than Baro and then you have air temp compensation also. I don’t know if you guys have any evos with 3bar map sensors and IAT stock .. mine is .. It came with an IAT sensor in the intake manifold and a 3bar map sensor.
#116
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The stock ecu has it but I think it must be changed to be scaled against MAP rather than Baro and then you have air temp compensation also. I don’t know if you guys have any evos with 3bar map sensors and IAT stock .. mine is .. It came with an IAT sensor in the intake manifold and a 3bar map sensor.
Maybe we can see if they can bolt right up/or make a spot for them so that we can have the ability to use the sensors if needed for this speed density conversion.
EDIT: I know the JDM MAP sensor is available to use, I am primarily talking about the AIT sensor.
Last edited by tkklemann; Oct 9, 2007 at 04:18 AM. Reason: Because I love Starbucks.