Big off idle stumble, whatt first? IFR? calc.vet? Something else I'm missing?

[statesman]

If your IFR is correct (matches actual injectors), and you hit the MAF 512 g/s limit, you then have to scale MAF, VE and IFR by some factor...

e.g. multiply each by 0.8 for example...

and then you have to look at all the tables that reference g/cyl (or simply g) and shift them down by the same factor

e.g. following on with 0.8 example, the HO/LO spark tables, you shift the 1.0 g column's contents to the 0.8 g column, 0.80 g col -> 0.64 g col...

you will have to do some interpolation

( yes it is tedious )

( yes, it is easier to scale by 0.5 instead of 0.8 )

It might also be worth pointing out that scaling the fuel and airflow affects calculated torque, which affects transmission shifts... so if you have to scale, then it's best to scale by the least amount possible (scaling by 0.8 is better than scaling by 0.5).

[Supercharged111]

Is any of this an indication of bad IFR? I really expected the truck to run normal pre-calc.vet. But then again I called these things 35 pounders and it still had that stumble. I'm confused as to the point of tuning the MAF if, when you do, you just end up scaling it back and undoing what you did in the first place? Would an SD tune make my life easier? I saw the COS tutorial stated that you had to but I have a friend who didn't. Not sure the state of his tune at the same time.

[statesman]

I'm fairly sure that the injectors you are using are the same injectors used in the ASA tune. Get a copy of the ASA tune and use the injector data from that tune file.

[Supercharged111]

Man I forgot all about that!

https://forum.efilive.com/showthread...e-spark-v-high

Well I can put that one to rest finally. I'm not 100% following why MAF scaling is required? IFR notwithstanding. It was scaled over farther before I started messing with it, so now I'm kind of lost on the point of messing with it. Unless the start and end values remain the same and it's everything between them that gets tweaked.

[joecar]

With the LS1 calibrations, there is an internal limit on the MAF at 512 g/s, so the MAF flatlines at 512 g/s.

This only matters if you're running MAF.

If you run SD then DYNAIR may flatline at 512 g/s, but this has no effect on VE g*K/kPa (i.e. VE is calculated ok, and DYNCYLAIR g/cyl is calculated from VE and is ok).


Post another log file, let's see if you hit it (with boost you should).

[joecar]

It might also be worth pointing out that scaling the fuel and airflow affects calculated torque, which affects transmission shifts... so if you have to scale, then it's best to scale by the least amount possible (scaling by 0.8 is better than scaling by 0.5).

Yes, a very good point.


( not only should any table referencing g/s or g be shifted down/left, but so should any table referencing anything that could be calculated from g/s or g ).

[Supercharged111]

With the LS1 calibrations, there is an internal limit on the MAF at 512 g/s, so the MAF flatlines at 512 g/s.

This only matters if you're running MAF.

If you run SD then DYNAIR may flatline at 512 g/s, but this has no effect on VE g*K/kPa (i.e. VE is calculated ok, and DYNCYLAIR g/cyl is calculated from VE and is ok).


Post another log file, let's see if you hit it (with boost you should).

Well my truck is only making like 3# on top of what we call atmospheric, so it only got up to 9000. Truck basically makes sea level power up here now, but now that the fueling is so much better I'll have another look at timing and order a smaller blower pulley. I imagine I'd still have to go to sea level to get it to peg the stock MAF. What do I lose by going SD? Anything important? Does the truck become more sensitive to weather/altitude changes? Does keeping it make tuning weird? Like with the handoff from the hi timing table to the boost timing table? I know I just corrected the MAF and calculated the VE. If it used erroneous MAF values to calculate the VE then something has to be off even though delivered fuel seems to be tracking with commanded. Maybe we should have that talk now, I know a little bit more of what I didn't know before.

[Supercharged111]

It appears my IFR is damn close if not bang on. I may just slap an LS1 regulator in so I can plug the 0 kpa value from the LSA tune in across the board on mine. I have 39#/hr in my tune which is at 3.5 bar and the ASA tune seems to base its numbers on 40# per hour at what I ASSume is 4 bar. My math says 42#/hr at the LS1 4 bar so I may still be off a little. Easy enough to make it the way GM intended.

[joecar]

MAP referenced FPR does provide benefits in that GenIII table B4001 only handles MAP in the range 20-100 kPa (i.e. vacuum in the range 0-80 kPa).

Same regarding the table B3701.

[Supercharged111]

So for boost does it just use the 0 kpa value? In my case that works nicely.