Maf Hypothetical
Maf Hypothetical hypothetically, if i set all the maf cell values from low hz to high hz to a g/sec value that i would never see in those hz cells,ie 8625hz=300 g/sec, 9000hz =400 g/sec, 10,000=500 g/sec, ectc what would happen in the these cells when hit if there isn't that much true air coming in.
given that 4000 rpm kicks into maf, ve is set so ltft are 0 when entering pe.
given that 4000 rpm kicks into maf, ve is set so ltft are 0 when entering pe.
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From: Katherine N.T Australia
Originally Posted by caliswangin916
hypothetically, if i set all the maf cell values from low hz to high hz to a g/sec value that i would never see in those hz cells,ie 8625hz=300 g/sec, 9000hz =400 g/sec, 10,000=500 g/sec, ectc what would happen in the these cells when hit if there isn't that much true air coming in.
given that 4000 rpm kicks into maf, ve is set so ltft are 0 when entering pe.
given that 4000 rpm kicks into maf, ve is set so ltft are 0 when entering pe.
With a MAF setup, the VE is only used during harsh throttle transitions, for other steady state conditions (like driving around town like grandma, cruising on the highway at a steady speed, and WOT over 4000) the MAF will control the fueling. DO NOT DO WHAT YOU ARE ASKING! 
What are you trying to accomplish anyway? 
What are you trying to accomplish anyway? for the last 2 posts, i thought that once in pe, i'm in open loop meaning no ve?
since i lowered my spark table to 21* at higher airmass vs higher rpm cells, my na wot is behaving like my 85 shot n2o wot. when going wot on both cases, my LTFT are negative before wot, so wot=o LTFT.
problem is that both cases will dip down to 12.0 afr or less for 1/3 second, then get up to 13.0 for 1.5-2 seconds, then get to 12.5 afr. my commanded pe is 12.5. na and n2o wot's are seeing different hz (na being lower hz than n20).this is happening with maf 4% above stock up to 8875hz and 9000+ hz is 7% above stock.
before i went to 21* in the spark table, na would be go to commanded pe without any lean spot.
since i lowered my spark table to 21* at higher airmass vs higher rpm cells, my na wot is behaving like my 85 shot n2o wot. when going wot on both cases, my LTFT are negative before wot, so wot=o LTFT.
problem is that both cases will dip down to 12.0 afr or less for 1/3 second, then get up to 13.0 for 1.5-2 seconds, then get to 12.5 afr. my commanded pe is 12.5. na and n2o wot's are seeing different hz (na being lower hz than n20).this is happening with maf 4% above stock up to 8875hz and 9000+ hz is 7% above stock.
before i went to 21* in the spark table, na would be go to commanded pe without any lean spot.
Originally Posted by 12secSS
With a MAF setup, the VE is only used during harsh throttle transitions, for other steady state conditions (like driving around town like grandma, cruising on the highway at a steady speed, and WOT over 4000) the MAF will control the fueling. DO NOT DO WHAT YOU ARE ASKING! What are you trying to accomplish anyway?
What are you trying to accomplish anyway? 
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WOT = Open loop fueling. OLF is commanded by the richer of 2 tables; 1)PE based on RPM and the 2) Open Loop Fueling Table based on ECT vs. RPM. This is of course on a stock GM operating system. EFI Live's Custom Operating Systems offer Open Loop Fueling based on MAP vs. RPM.
Open Loop fueling is only as accurate as the calibration is setup by using a wideband O2 to account for the changes your modded car has. Most here will agree that the vehicle needs to be put into Open Loop Speed Density (No MAF, Fuel Trims, PE, DCFO) first and foremost and recalibrate the VE table with a WBO2. If you then choose to run the MAF you will then need to rescale it.
Open Loop fueling is only as accurate as the calibration is setup by using a wideband O2 to account for the changes your modded car has. Most here will agree that the vehicle needs to be put into Open Loop Speed Density (No MAF, Fuel Trims, PE, DCFO) first and foremost and recalibrate the VE table with a WBO2. If you then choose to run the MAF you will then need to rescale it.
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Originally Posted by Doc
WOT = Open loop fueling. OLF is commanded by the richer of 2 tables; 1)PE based on RPM and the 2) Open Loop Fueling Table based on ECT vs. RPM. This is of course on a stock GM operating system. EFI Live's Custom Operating Systems offer Open Loop Fueling based on MAP vs. RPM.
or am i looking at the wrong tables? i don't see an ect vs rpm table in hpt.
Last edited by caliswangin916; Apr 6, 2007 at 02:03 PM.
Ahem, yes, (third beer waiting for a delayed flight to Madrid out of JAX) ECT vs Map stock. My advice to you is set one of the two tables (PE or ECT to "1") Just so you are not in a constant battle of "Who is commanding what?" Since you are using HPT, I would advise setting your PE table to "1," and use the temp table.
outside temp was about 55-60* and my iat was 68* or less.
I bumped my VE at the 100 and 105 MAP cells up 3% above what i had it (which is 102 from the stock of 95).....i upped my OLFA to get a richer afr, richest was 1.17 which is 12.49 afr in the higher map/ect cells,,,,,,,,,but i was in the 12.3 ranges on wot.
i did some logging when it was cold out and my iat was 68* or less during na, my wot afr was consistently around 12.3 and not the 12.5 that i thought i was commanding in pe and, cot, and OLFA.
i was logging closed loop fuel (YES or No in the staus bit) and never went into open loop under wot or any other throttle possition. from what i understand the status bit tells me if i'm in open loop or not????
i have a 2000 operating system, is it MAYBE because there is a table that i can't access on this operating system that is controlling my fueling on WOT? such as an iat vs fuel adder that is on 01-02 operating system that i don't have in my 2000 operating sytem.
MY OPEN LOOP STFT IS SET TO DISABLED... is this a why i'm not hitting Open Loop?
I bumped my VE at the 100 and 105 MAP cells up 3% above what i had it (which is 102 from the stock of 95).....i upped my OLFA to get a richer afr, richest was 1.17 which is 12.49 afr in the higher map/ect cells,,,,,,,,,but i was in the 12.3 ranges on wot.
i did some logging when it was cold out and my iat was 68* or less during na, my wot afr was consistently around 12.3 and not the 12.5 that i thought i was commanding in pe and, cot, and OLFA.
i was logging closed loop fuel (YES or No in the staus bit) and never went into open loop under wot or any other throttle possition. from what i understand the status bit tells me if i'm in open loop or not????
i have a 2000 operating system, is it MAYBE because there is a table that i can't access on this operating system that is controlling my fueling on WOT? such as an iat vs fuel adder that is on 01-02 operating system that i don't have in my 2000 operating sytem.
MY OPEN LOOP STFT IS SET TO DISABLED... is this a why i'm not hitting Open Loop?
Originally Posted by caliswangin916
is it a suspect that my MAF is bad thus why i'm not getting into Open Loop?
1) Commanding A/F is one thing, producing it is another, you must make the necessary modifications for your airflow tables (via MAF or SD) to achieve your commanded A/F
2) Change your PE EQ Ratio table and 90-100kpa OLFA rows to the same commander, if they are both asking for the same thing, then there's no bother with which one is being used (more than likely your PE will always be referenced first at this point if they values are the same, PE IS NOT OL, OL IS OL, this may be why you are not seeing a switch).
3) Now go log your A/F, and make adjustments to your MAF in the areas where you are seeing A/F discrepancy. Go for another log, and if you like the results than all is well. Usually bad MAFs have a pretty obvious way of letting you know that they're not happy.
Originally Posted by ZL1Killa
you snap the throttle down and it doesn't show your fuel status as OL??
can you give me a scenario that will get me into open loop if what i did above doesn't guarantee an open loop.
after i changed my OLFA to command 12.5 and bumped up my ve cells, my afr is 12.3 when i am commanding 12.5 in OLFA table which i am also commanding in PE. but supposedly i'm not even in Open Loop. the logs after these changes, i didn't get the 1.5-2 second lean spot(13.0) that i was getting before.
example 1 and 2
1. Difference now is on one of my wot= afr dipped to 12.0, then went lean to 13.0 and has a linear downslope for 1.5-2 seconds before it gets to 12.3 when before these current changes. it would dip to 12.0 and stay consistently at 13.0 for 1.5-2 seconds and then get to 12.5.
2. wot will have NO dip in afr, it will just have a nice 1 second linear downslope to 12.3.
i noticed that iat for example 1 was 70* when iat for example 2 was 68*.
i looked at an 02 stock edit and there isn't any fuel adder in these iat cells. so i'm assuming if there is this table in a 00 that i can't access, that it is set to 0 as well?
i'll leave everything as is commanding 12.5 for now and tune the maf.
CL= Closed loop temp enable=max value
Fuel trims disabled
PE set to 1.0
MAF set to fail, unplugged if IAT sensor seperate (Fbody)
Zero out the MAF table if Ybody that has IAT integrated into MAF
Most importantly the MAF has to fail in order to enter OL!
One of the aforementioned conditions have not been met in order to have the troubles you have described. Review.
Fuel trims disabled
PE set to 1.0
MAF set to fail, unplugged if IAT sensor seperate (Fbody)
Zero out the MAF table if Ybody that has IAT integrated into MAF
Most importantly the MAF has to fail in order to enter OL!
One of the aforementioned conditions have not been met in order to have the troubles you have described. Review.
also, on a long decel you should go into OL... at least my car does..say like from 3200 and just let it go down at one point it will go OL then tap the gas again and it goes CL...
dude i seriously have no clue what the hell your car is doing/why it should go OL under WOT. hell set your OLFA (open loop fueling table) to 13.0 and set PE to 12.5 or something like that and see
dude i seriously have no clue what the hell your car is doing/why it should go OL under WOT. hell set your OLFA (open loop fueling table) to 13.0 and set PE to 12.5 or something like that and see