Trying to make sense of Power Enrichment
07-14-2018, 10:09 AM
#22
The information is out there. I have included this in my training materials and classes for a long time. That doesn't mean that people pay attention or that some "professional tuners" have taken the time to learn how the systems really work for themselves. There is a LOT of village wisdom being passed around, so it's sometimes difficult to know who to believe, even from some "professional trainers".
I'm curious about your thoughts on the use of the BE table for turbo and supercharged applications. I know some guys here avoid using BE, I have found it very useful with small single turbo set ups.
07-14-2018, 11:12 AM
#23
TECH Addict
seems pretty obvious.
i disable pe entirely and didnt understand the need for it.
but after reading through this thread i realized its because ive been using the efilive COS for so long i forgot that their 3d commanded fuel vs rpm table isnt normally available.
so my input isnt really relevant in this thread, apologies.
i disable pe entirely and didnt understand the need for it.
but after reading through this thread i realized its because ive been using the efilive COS for so long i forgot that their 3d commanded fuel vs rpm table isnt normally available.
so my input isnt really relevant in this thread, apologies.
07-14-2018, 12:22 PM
#24
TECH Resident
Thread Starter
It's all good. Does EFILive modification replace the coolant-temp axis of the open loop fuel table with an RPM axis? Or did they add a whole new table?
07-14-2018, 12:25 PM
#25
TECH Addict
Im not sure what table you mean, but the table im talking about is probably new.
here is the description of the table in the software, its for COS5 of the 12212156 os:
B3647 Commanded fuel vs RPM
This table is only available in some custom EFILive Operating systems, it allows you to define any commanded fuel.
The values in this table may be blended with the values in {B3649} "(not available in this operating system)".
See also:
- {B3601} Ratio of Air to Fuel for Stoichiometry
- {B3660} (not available in this operating system)
here is the description of the table in the software, its for COS5 of the 12212156 os:
B3647 Commanded fuel vs RPM
This table is only available in some custom EFILive Operating systems, it allows you to define any commanded fuel.
The values in this table may be blended with the values in {B3649} "(not available in this operating system)".
See also:
- {B3601} Ratio of Air to Fuel for Stoichiometry
- {B3660} (not available in this operating system)
07-14-2018, 04:01 PM
#26
TECH Resident
Thread Starter
I probably should have asked, "does the open loop fuel based on ECT and MAP table still exist in that custom OS?"
Because if doesn't show up anymore, that would be a pretty strong hint that EFILive just re-purposed that existing table to use RPM instead of ECT.
Because if doesn't show up anymore, that would be a pretty strong hint that EFILive just re-purposed that existing table to use RPM instead of ECT.
07-20-2018, 06:02 PM
#28
Best not to think of those open loop surfaces as enrichment, per se. Neglecting some of the finer points, the purpose they serve is to account for the fuel that does not participate in combustion. When the OL multiplier is something like 1.5 in cooler IVT regions, that means an extra 50% fuel mass needs to be injected to get 100% of the target fuel to participate in the combustion. When things are cold, not all of the injected fuel vaporizes. Some of it does, but the remainder that doesn't is mostly lost to a partial diffusion-style combustion or ends up impacting the cylinder wall where it either vaporizes after chamber heat is too low to ignite it or doesn't vaporize at all and just gets pushed into the crank case. Even though it is enrichment per the conventional definition, the goal is still stoich.
07-21-2018, 12:29 PM
#30
TECH Resident
Thread Starter
Best not to think of those open loop surfaces as enrichment, per se. Neglecting some of the finer points, the purpose they serve is to account for the fuel that does not participate in combustion. When the OL multiplier is something like 1.5 in cooler IVT regions, that means an extra 50% fuel mass needs to be injected to get 100% of the target fuel to participate in the combustion. When things are cold, not all of the injected fuel vaporizes. Some of it does, but the remainder that doesn't is mostly lost to a partial diffusion-style combustion or ends up impacting the cylinder wall where it either vaporizes after chamber heat is too low to ignite it or doesn't vaporize at all and just gets pushed into the crank case. Even though it is enrichment per the conventional definition, the goal is still stoich.
Learning all the time.
07-21-2018, 04:43 PM
#31
The OL table you refer to in the first post isn't what's used for PE fueling. There are tables for that. The OL table is simply base fueling for open loop... aka when the car is cold and warming up it reads from there or if you disable closed loop to idle a big cam.
The PE is used for load (which is why it's enabled via TPS% and kPa pressure). This keeps cruising at 1 lambda and PE at whatever you set it to (something like 1.16-1.18 EQ ratio).
BE is additional fueling on top once you're above 105 kPa. I would advise against that. Once you're into throttle, boost is going to happen. No need for secondary boost enrichment. Set the PE at 1.22-1.24 and let it eat.
The PE is used for load (which is why it's enabled via TPS% and kPa pressure). This keeps cruising at 1 lambda and PE at whatever you set it to (something like 1.16-1.18 EQ ratio).
BE is additional fueling on top once you're above 105 kPa. I would advise against that. Once you're into throttle, boost is going to happen. No need for secondary boost enrichment. Set the PE at 1.22-1.24 and let it eat.
07-22-2018, 01:21 PM
#32
TECH Resident
Thread Starter
07-22-2018, 01:59 PM
#33
It matches exactly what I said. You shouldn't be using that table for WOT as it's for cold start and warm up conditions. The 2 tables serve different purposes. PE is for WOT and based on RPM, the OL AFR commanded table is for cold start and warm up conditions.
07-22-2018, 06:17 PM
#34
TECH Resident
Thread Starter
Suppose the OL fuel table calls for 12.5 AFR (1.17 EQ) and the PE table calls for 13.0 AFR (1.13 EQ). And PE is active.
Based on "The factory PCM looks at the richer of "commanded fuel when in OL" and "PE modifier based on RPM"...then the PCM would use 12.5 (1.17) because the OL table is richer.
'
Based on "The OL table you refer to in the first post isn't what's used for PE fueling."...then the PCM would use 13.0 (1.13) because the OL table isn't used.
I'm having trouble understanding how both of those things could be correct at the same time.
Based on "The factory PCM looks at the richer of "commanded fuel when in OL" and "PE modifier based on RPM"...then the PCM would use 12.5 (1.17) because the OL table is richer.
'
Based on "The OL table you refer to in the first post isn't what's used for PE fueling."...then the PCM would use 13.0 (1.13) because the OL table isn't used.
I'm having trouble understanding how both of those things could be correct at the same time.
07-22-2018, 07:23 PM
#35
Suppose the OL fuel table calls for 12.5 AFR (1.17 EQ) and the PE table calls for 13.0 AFR (1.13 EQ). And PE is active.
Based on "The factory PCM looks at the richer of "commanded fuel when in OL" and "PE modifier based on RPM"...then the PCM would use 12.5 (1.17) because the OL table is richer.
'
Based on "The OL table you refer to in the first post isn't what's used for PE fueling."...then the PCM would use 13.0 (1.13) because the OL table isn't used.
I'm having trouble understanding how both of those things could be correct at the same time.
Based on "The factory PCM looks at the richer of "commanded fuel when in OL" and "PE modifier based on RPM"...then the PCM would use 12.5 (1.17) because the OL table is richer.
'
Based on "The OL table you refer to in the first post isn't what's used for PE fueling."...then the PCM would use 13.0 (1.13) because the OL table isn't used.
I'm having trouble understanding how both of those things could be correct at the same time.
07-22-2018, 08:27 PM
#36
TECH Resident
Thread Starter
I see now. I've been thinking mostly in terms of "how does the PCM work?" and you guys are moving on to "how should the PCM be tuned?"
I take the answer to my "how does it work" question is 12.5 because the OL table is richer?
I take the answer to my "how does it work" question is 12.5 because the OL table is richer?
07-22-2018, 10:46 PM
#37
I have also found that it doesn't work like a second adder, but rather like most fueling tables the PCM defaults to the richest one. If that's the BE in a certain kPa and PE in another tps/rpm area then thats what you get. It appears to blend them pretty seamlessly.
