what about ve correction factor setting it to 0 or 1 would that make it only use mas air flow or ve only
Has any one done this?
what about ve correction factor setting it to 0 or 1 would that make it only use mas air flow or ve only
Has any one done this?
The facts are both models are used and needed for the torque model to function properly....this is not opinion its fact. All this torque control stuff that everyone keeps focusing on is all useless unless the airflow model is correct. Only then can any torque post process tables be manipulated. I've seen the calculation and there both weighed.Originally Posted by 69camaro5speedefi
Go fix your MAF curve then go solve the the SD model and a lot of things will clean up fast....we may think we are smarter then GM but we are not....we are missing so much stuff to truly do it right the least we can do is get it as close as we can with the tools we have.
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The problem I have with mas air flow and boost is having the same command AFR at 2 lbs of boost as I do 10lbs or maybe even 15 or 20
Its ok if you have 2 throttle speeds low and wot but in a heavy yukon denali going up a hill at 3 or 4 lbs of boost it will be rich if you have the wot tune for higher boost
gm fix, bring pe in late keep timing out(save pistons) until pe is activated then add timing off pe
I watched a gm truck show that went city to city showing off there duramax,8.1 back in like 2001 or 2002 ish
They had a chassis dyno to compare gm ,ford,dodge trucks
When they tested the 8.1 the exhaust turn cherry red ,later I Had a 8.1 avalanche 60 second pe delay timing would be like 0 when you go wot
I know where the red exhaust comes from lol ,guess they do any thing to save gas
Red exhaust comes from very little spark timing.
What does boost matter vs airflow? Boost is just a measure of restriction and is only an indirect reference to airflow. The MAF doesn't care about boost, it measures lb/min. You tune the MAF, not the PE table. At 2psi of boost it will be at a different point in the MAF curve than it will at 10psi.
At 2psi of boost it will be at a different point in the MAF curve than it will at 10psi
hmmm my data logger must be reading false numbers then, I have seen pretty high boost numbers at 1500 rpms and low boost numbers at 4500 ish rpms guess boost doesn't matter
What does RPM have to do with it, either? Again, the MAF is measuring airflow through the intake tube. You can flow X amount of air at 1500 RPM and 80% pedal and the same amount of air at (for example) 4000 RPM and 40% throttle. Both combinations will be at the same point in the MAF curve. The MAF doesn't care about boost level or RPM. Generally speaking and all else equal, more RPMs mean more air (unless you are decelerating) and more boost means more air and a more open throttle means more air......but the MAF doesn't care about the combination.
right mas air doesn't care so if you command 11.3 afr at 1500 rpms and 20 lbs boost you still command it at 1500 and 2 lbs of boost
MAF and boost are too different things. MAP reads boost. MAF reads airflow.
MAF=Flow
MAP=Pressure
If you are flowing X amount of air then you need a certain amount of fuel.
High MAP at low RPM doesnt mean high airflow. I can stuff 135psi of "boost" into my cummins race truck at 3,000rpm. Doesn't mean that I am flowing more air than I am at 115psi at 5,500rpm. I'm have a higher airflow reading (MAF) at 5,500 than I have at higher boost at 3,000rpm.
Look at MAP and MAF and RPM. Then you should see the full picture.
If you are seeing the same MAF reading from 2500-6000 RPM then you are potentially maxing out the MAF. I doubt you are, but its possible. What kind of frequency are you seeing? Can you post a log?
until the computer understands that a certain MAF frequency equals a certain amount of air, then your ECU cannot properly calculate the amount of fuel needed to equal the amount of air being ingested. Right now, you aren't anywhere near the point of needing to mess with the PE.
ok kool so you run the same fuel in your cummins with 2 lbs of boost as you do 115 lbs of boost
Actually I do.
When I read your question I took it to mean, do I run the same fuel in the tank.
To that question, yes I do.
If your mean do I run the same quantity of fuel, no, I do not.
Its obvious that I run more fuel at higher boost. If that higher boost is higher airflow.
In my example I run less fuel at 3,000RPM with 135psi of boost, than I do at 5500RPM with 115psi boost.
Because, at 115psi at 5,500RPM, I am actually moving more air than I am at 135psi at 3,000RPM.
you have one pe adjustment if it's 2 lbs of boost or 50
You have a valid point there with only one PE setting. But the timing is set by g/cyl so you can set your PE to kick in at say 5 psi, and using your maf to "notice" the extra air you can be pulling timing and then when you hit PE maybe add more timing and then as boost goes up probably be pulling timing again tho right?The problem I have with mas air flow and boost is having the same command AFR at 2 lbs of boost as I do 10lbs or maybe even 15 or 20
Its ok if you have 2 throttle speeds low and wot but in a heavy yukon denali going up a hill at 3 or 4 lbs of boost it will be rich if you have the wot tune for higher boost
gm fix, bring pe in late keep timing out(save pistons) until pe is activated then add timing off pe
I watched a gm truck show that went city to city showing off there duramax,8.1 back in like 2001 or 2002 ish
They had a chassis dyno to compare gm ,ford,dodge trucks
When they tested the 8.1 the exhaust turn cherry red ,later I Had a 8.1 avalanche 60 second pe delay timing would be like 0 when you go wot
I know where the red exhaust comes from lol ,guess they do any thing to save gas
On a 2 bar OS it would be easier for me to understand sometimes if they set timing by MAP.
1999 s10 blazer trailblazer edition nv3500 swap
2006 GMC ccsb 4x4 duramax/allison
you add fuel gradually as boost goes up ,with pe it doesn't work that way
PE is one part of your puzzle. The PE is getting added or subtracted from the rest of the equation. You can try to shortcut the tune by just dialing in PE. YOur pe table will look crazy.
Until you dial in the VE table and the MAF, the rest of the perameters your messing with are bandaids to fix a bad base tune. If all you want it to do is make a drag pass, then feel free to ignore a few tables. (I wouldn't)
If you want it to drive well and make power and live a healthy life, then dial in the VE and the MAF. The VE has a huge impact on part throttle driving and quick throttle changes. The MAF is telling the engine quite precisely how much air is being ingested. The MAP is telling the ECU at what pressure you're ramming it in.
At a minimum dial the VE in. The computer will know whats going on at least.
If you want it to do well if the weather changes a decent bit (such as the four seasons of the year, humidity, etc...), then ddial in the MAF.
If you want to do it right and treat your customer right, then dial them both in.
maf timing is great there needs to be a g/cyl command afr table
Actually I'm running more fuel even as the boost drops, because my RPM has climbed and my airflow is increasing. I'm just ingesting more of it. Boost is just the measure of restriction to my airflow.
Think about this for a second. A naturally aspirated car goes into PE without going into boost so your issue is not with needing PE and BE although that would be nice and is available in custom OS for older PCMs. What I mean is, once you are past a certain load and pedal and RPM you want PE fueling and it doesn't have to correlate with boost.
I command PE before I ever hit boost, like 80 or 90 kpa, sometimes even lower. The MAF is what controls whether or not you are hitting your commanded fueling, Lambda 1.0 or .85 or .75, doesn't matter. As the MAF rises, so does fueling, because your MAF is modeled after the airflow going into the engine.
Use your PE criteria to properly command when you want the enrichment. Don't get so hung up on boost at low RPM, just make sure your MAF curve is correct and your PE criteria makes sense and you will be fine.
pe is good for na from 90 kpa to 101
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