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

[Supercharged111]

It sure looks that way. Fixing the fuel to this extent is new to me. There's a lot more to it than the standalone I used to work with and a lot more depends on getting it right. Once I finally get it, I'll repeat this process by 411 swapping my dually. Hopefully after that ordeal I'll become more efficient.

[joecar]

So you're running rail pressure at 3.5 bar...?

with an un-referenced regulator (I don't remember)...?

[Supercharged111]

3.5 bar vacuum referenced. If there's a 4 bar at home then I'll be set.

[dian]

how can op be pegging the maf at 100 kpa? or 109 or even 135?

[Supercharged111]

If I had an engine that breathed more it would be quite feasible. I'm not pegging the MAF right now, and if I remember to rescale tonight I probably won't even at sea level. I just don't see this thing making much, if any, north of 400hp at sea level. NA it'd be in the 300 range so add whatever the "boost" gives me to that.

[statesman]

If you're staying with the 3.5bar regulator, then put 4.52 into your IFR table and put the stock values back into your MAF table... you should be fairly close with that.

[Supercharged111]

So I did a little digging and noticed something interesting: quite a few GM tunes have the MAF pegging early. The Express van did not, but the Camaro did with the early MAF. That makes me think that maybe I did get the MAF halfway right since everything else seems to be right, at least that's what I tell myself.

5.7 Vortec truck with black box PCM.



5.7 Vortec van with 411 PCM and same MAF sensor.



LS1B Camaro, same PCM same MAF.



Unless GM fudged the numbers? Corvette MAF table looks very similar to the Camaro's. As far as the off idle stumble goes, I have some transient tables I got from Alouicious that he ran way back in the day on his Whipple'd 411'd truck so hopefully I can put that one to bed. Too many projects. . .

[Supercharged111]

Alright! That transient fueling table felt like it really did the trick! It's exponentially different from stock, even that far off of what I concocted by globally doubling stock I don't remember how many times over. The only way I could really figure to logically approach this was to log AFR on a VE chart and filter by TPS changing at a certain rate per second but never got around to it. I experimentally maxxed out the table and the truck straight up wouldn't run, so that told me its effects were more far reaching that I currently comprehend. Here's stock.



Here's what I hacked together.



And here's what Al intelligently put together.



Just need to drive it a bit and validate it. On another note, the platform change seems to have allowed my truck to shift all gears in 4lo, but they shift way late/high. Not too sure what to make of that. Here's my tune, any takers?

411 Whipple V20 Transient Fueling and 4LO.tun

[statesman]

Here's my tune, any takers?

Any takers for what?

[Supercharged111]

Why the truck shifts so high out of 4lo. Starting to think the platform change didn't do the trick. Transient is night and day better though.