fuel pump low/high voltage transition table
#61
Evolving Member
iTrader: (3)
Join Date: May 2008
Location: Utah
Posts: 472
Likes: 0
Received 0 Likes
on
0 Posts
ok, i'll assume that all tephra roms inherit from their corresponding numerical roms.
back to the other question, is there a thread that compiles all the tables not included in V7 that we need to add manually?
back to the other question, is there a thread that compiles all the tables not included in V7 that we need to add manually?
#70
Evolved Member
iTrader: (4)
All the first post code snippets are messed up still in this thread....
anybody have the def for 94170015?
anybody have the def for 94170015?
#72
Evolving Member
iTrader: (2)
<table name="Engine Speed" address="642e" type="Y Axis" elements="10" scaling="RPM"/>
</table>
<table name="Low/High Voltage Transition Hysteresis" category="Fuel" address="1a74" type="1D" level="1" scaling="Load16"/>
#73
Evolved Member
iTrader: (4)
Bump for Question. COuld not find answer anywhere.
What are the low fuel pressure actual numbers in PSI?
What are the high fuel pressure actual numbers in PSI?
I am interested, for I just did an upgraded FPR with gauge. At Idle, what should low pressure read?
Thanks in advance.
What are the low fuel pressure actual numbers in PSI?
What are the high fuel pressure actual numbers in PSI?
I am interested, for I just did an upgraded FPR with gauge. At Idle, what should low pressure read?
Thanks in advance.
#74
Evolving Member
iTrader: (2)
Bump for Question. COuld not find answer anywhere.
What are the low fuel pressure actual numbers in PSI?
What are the high fuel pressure actual numbers in PSI?
I am interested, for I just did an upgraded FPR with gauge. At Idle, what should low pressure read?
Thanks in advance.
What are the low fuel pressure actual numbers in PSI?
What are the high fuel pressure actual numbers in PSI?
I am interested, for I just did an upgraded FPR with gauge. At Idle, what should low pressure read?
Thanks in advance.
Ideally, relative fuel pressure (pressure difference between injector input and output) should remain 3 bar (if stock regulator is used).
At idle, since intake manifold is in vacuum, the fuel pressure should be set to 3 bar minus whatever the vacuum gauge reads. For example, if the vacuum is 0.7 bar, the fuel pressure should be 2.3 bar.
Another way is to remove the vacuum hose to FPR and set the fuel pressure to 3 bar (if the atmospheric pressure stays relatively constant).
The reason why Mitsubishi put this low/high transition table is to reduce noise and extend lifetime of fuel pump for vacuum / low boost condition where most pumped fuel is returned to fuel tank anyway,
and I think the biggest reason why we still want to touch this table is that due to restrictive stock fuel return line (the first bottleneck is actually the small orifice at the pump housing), high flow fuel pump can give overly rich condition during boost transition.
#75
This table defines Low/high input voltage transition to fuel pump, and it does not necessarily meaning fuel pressure change.
Ideally, relative fuel pressure (pressure difference between injector input and output) should remain 3 bar (if stock regulator is used).
At idle, since intake manifold is in vacuum, the fuel pressure should be set to 3 bar minus whatever the vacuum gauge reads. For example, if the vacuum is 0.7 bar, the fuel pressure should be 2.3 bar.
Another way is to remove the vacuum hose to FPR and set the fuel pressure to 3 bar (if the atmospheric pressure stays relatively constant).
The reason why Mitsubishi put this low/high transition table is to reduce noise and extend lifetime of fuel pump for vacuum / low boost condition where most pumped fuel is returned to fuel tank anyway,
and I think the biggest reason why we still want to touch this table is that due to restrictive stock fuel return line (the first bottleneck is actually the small orifice at the pump housing), high flow fuel pump can give overly rich condition during boost transition.
Ideally, relative fuel pressure (pressure difference between injector input and output) should remain 3 bar (if stock regulator is used).
At idle, since intake manifold is in vacuum, the fuel pressure should be set to 3 bar minus whatever the vacuum gauge reads. For example, if the vacuum is 0.7 bar, the fuel pressure should be 2.3 bar.
Another way is to remove the vacuum hose to FPR and set the fuel pressure to 3 bar (if the atmospheric pressure stays relatively constant).
The reason why Mitsubishi put this low/high transition table is to reduce noise and extend lifetime of fuel pump for vacuum / low boost condition where most pumped fuel is returned to fuel tank anyway,
and I think the biggest reason why we still want to touch this table is that due to restrictive stock fuel return line (the first bottleneck is actually the small orifice at the pump housing), high flow fuel pump can give overly rich condition during boost transition.
It is not used to set a particular fuel pressure. That job is handled entirely by the fuel pressure regulator as long as there is no overrun. Overrun occurs when fpr can't flow high enough to control fuel pressure. This would happen if the fuel pump were running at full voltage at idle and light throttle. It causes AFRs to become uncontrollably rich at idle and ligh cruise, and generally f's with the ability to control AFR. This happens to people who hardwire their fuel pumps (and thereby remove the factory capability to supply low/full voltage).
Raceghost - To answer your idle fuel pressure question, the standard fuel pressure at idle with the FPR vacuum line disconnected from the intake manifold is 43.5 psi. Don't try and set the fuel pressure with the vacuum line connected. I'll comment that the stock FPR is actually very good, and there is no need to upgrade unless you have a desire to run higher base fuel pressure than stock. For most people, there is no need to use anything other than the stock FPR.