ok, so how do we account for reversal or scavenging? i'd like to see the 'simple calculations'

 

TQ output vs airflow vs fuel. It's a rough estimation but it can put the head on the problem quickly.

Or you can look at airflow vs fuel quantity.

 

how how does this help? going off sensor data will give me false readings due to reversion/scavenging. going off wb/fuel will give me false readings due to wb being freaked out with fresh air in exhaust.
been there, done that, did not get the t-shirt tho...

 

LS1Curious, you missed my post:

I have been side-lining this conversation, but I just have to ask/add the following. Please explain, and thanks for your time.

 

whatever goes through the MAF goes into the engine.

 

Let me know how those cylinder walls look in 40k.Fuel wash will eat rings.Most likely thats why such a high number of cars here consume oil.

You can work around that by zeroing out the Load AF multipliers and using PE fuel and Dynaair of VE table fueling to fix those issues. Use the PE for high load like its designed to be used and use Dyna-air to fix Tip in throttle issues.

 

................

 

I would tend to disagree. The numbers of cars that I have personally seen tunned this way that consume oil all tend to be shorted lived for ring seal are enourmous.


I think you seem to misunderstand the intetion of the Software engineers. The software engieers are trying to do one thing and one thing only. Limit the amount of deviation fron 14.7:1 as much *** possiable. they are doing this to keep the catalyst in its efficnecy range. The only way to force it to fuel at 14.7:1 during large transients and such other throttle deltas was to use a VE table to correct Surge volume that occur from the MAf ducting.

Think of it like this.

Open a tank of air at a very slow rate. Open that same tank at a fast rate.You eventually get the same amount of air. But when you are measuring the amount of air the amounts are the same but initially the rapid opening showed higher momentarily.

Hence the VE table and DynAir.the VE table correct for the Lag in measurement. Now by forcing Openloop and turning the Openloop correctors back on to zero you have created the same effect withouth the NBo2 intrusion.

No that we are back to stioch speaking in terms of chamber AF's not observed AF's we have to start working to make the engien happy.

the throttle is definatley a better determination of load then map in a Large camshafted engine. No argument there. Espcially at low speed. But the way GM set up the software to work was to have the VE table be the Delta corrector and the PE tables to give the engine best power fueling during high load.

Its not a very hard concept to grasp.

 

....... still not onboard with ya here

 

All this yakity yak yak! I plug in my wideband and let it do the talkin!

I must admit though, I do love a spirited discussion.

 

I am not the only person. People ignore the proof. Oil consumption on ls1 cars with camshafts is a huge problem.Its certianly not all fuel related but its definately not all other issues either. Just look at the numbers of cars with oil in the intake. Obviously a sign of blowby. Blowby is genrally cuased by lack of oil sealing the rings to the cylinder walls.





I wouldn't say the MAF is slow by any stretch. In fact its exremtly fast. As fast as the MAP. The bottle exmaple I was making before. the MAF can actually Oversample.




OLFA is an offset table. If you have an 02 sensor failure then you overichen the engine to protect the catalyst. Part one of the function of that table. Part 2 is it allows for enrichment at cooler engine tempatures. I wouldn't ditch all the values just the high load operating temp values.

Lets look at it from this angle.

Airflow x fuel injector. what changes here ? If the MAF calibration is factory and correct and the injector size is correct why would the fueling be off in the first place.It shouldn't be. Regardless of displacement the amount of air and fuel and the coefficient of those 2 will be constant. the observation of varying Af's could be a million other factors totally unrelated to steady state fueling.




I did not mean for that to come off as condescending.I am short on sleep. My apologies.


Perfect is a subjective term.Define it. What exactly does perfect blanace out ? Secondly being there is no baro correction that is arbitrarily applied to the fueling calcs as the base of the fueling output the calibration will meander alot without a MAF.


There may be more then one way to skin a cat for sure. But the hype about SD is just that Hype. There is a way to modify the operating system to run true SD but it would require some heavy work on the OS software and rewriting of the primary fueling algorythm.

Mostly it would involve setting up a true baro offset and a good fundemental Airflow calculation.

Don't take me as saying it can't be done.It has been done. But the evidence is in that the Calibration never meets the weather the way it is supposed to.

 

I am VERY pro-MAF unless it is being maxed out. I also will not do SD tunes without one of the custom OS's (I use HPT so it's their 1,2, or 3 bar SD OS's) that is offered by HPT or EFIL.

If you have a large cam and leave the VE stock it WILL be very rich from start-up until trimming begins at CL operation. What I am talking about has nothing to do with dynamic airflow; the car is sitting still idling with no throttle and fueling more from VE than MAF... the gross VE error is now gross AFR error. Also, I have a hard time beleiving that each MAF shipped hits the prescribed curve as well, and I don't know what effect common changes like lids and bellows may have on the MAF, especially descreened units, even if OEM.

 

Thats the misconception. Unplug the MAP sensor and watch the AF stay the same. The only time the MAF is not in use is during cranking.

MAF accuracy is 1/2 % tolerance. Its insanely minmal. ducting will have minmal impact unless the unit is descreened. You can just toss the factory curve out the window at that point.

I have been working on a dissasembly of a Custom OS and I don't think I have seen much of anything yet. Its a bit of work but If i figure out whats been done I will pass the info along. I won;t however post exactly where and whats been changed.

 

Well going from what you've said so far, the MAF and VE are always right, so don't adjust them, and the OLFA shouldn't be touched either... so a cammed car that is running rich as hell from cold-start to CL... what do you do to correct AFR?

 

Desired and or parked airflow?

{B4307} DESIRED AIRFLOW

Used to reduce airflow as the engine warms up.
Although listed in the "Idle" section, this calibration also controls the base airflow for non-idle conditions.

 

Thats the thing. You don't run CL on a car with a decent sized camshaft.

You use the OLFa to correct the AF. I also said VE made need adjustments.

 

 

ok, so please enlighten us, just what is The Right Way of tuning?

Last I checked my car would not even start with MAP sensor unplugged. I don't know how else to describe to the computer the changes in Volumetric Efficiency from the mods but to use a Volumetric Efficiency table. And I've proven on my own car that a stock MAF calibration on a MAF that measures airflow at one point while the airflow is not universally distributed through the MAF housing is not gonna work unless you kept your intake perfectly stock.

SD works, it has a MAP sensor, it has temp tensors, with a good bias model it can figure out the temps quite reliably, as long as the wideband is healthy, and the injector data are correct. and the equations for all this stuff are figured out, it doesn't take much beyond basics physics.

and you still haven't really answered my reversion question. MAF picks up the air backing up quite badly. i've had big cam cars that would run perfect in SD but no matter what amount of MAF tuning i've done, it would never work right in MAF.

why do you say we need a baro sensor? isn't there a baro sensor in there somewhere? how else does it get manifold vacuum which is mandatory to know to operate injectors?

 

Baro is updated at key on and WOT. If it sees a number higher than what it currently has, it'll update to that number.

 

I didn't say baro doesn't update.Its just not used in the airflow calculations the same way the older Ideal Gas Law SD systems did. Its more od a decoration then an actual value.