Project 3400 Roller Cam Block (Page 52/82)
carbon JUL 24, 04:04 PM

quote
Originally posted by ericjon262:

doesn't really matter, sequential only really effects bottom end stability, by the time you start getting higher in the RPMs, the fuel is moving too fast for there to be a notable difference

in will's case, each of his injectors are supplying ~26 HP, which equates to ~160 HP for a V6.




Agreed on the value of SFI, but where did you get your math from? 312HP, at the wheels even, doesn't equate to 26HP each... its ~39HP, which equates to ~236HP at the wheels... did I miss something?
carbon JUL 24, 04:15 PM

quote
Originally posted by sleevePAPA:


eh?

batch fire(single injector driver ECMs) fires the injectors twice per revolution, sequential each injector once per revolution. So batch firing injectors have roughly half the time to fire before they are static. If you look at the vid I posted above, just looking at the realtime data, the PW is ~9.41 ms at 6100 rpm. Thats why the WB goes rich, the injectors are static. Now if I was using the EEC with sequential injector firing, it would be ~55% roughly.



If that's the case why do all GM ECMs drop SFI and switch to batch as RPMs increase above ~3500RPM? It can't be because there's less time to inject with batch fire...

My misunderstanding... sorry!

[This message has been edited by carbon (edited 07-30-2013).]

sleevePAPA JUL 24, 04:25 PM

quote
Originally posted by carbon:


If that's the case why do all GM ECMs drop SFI and switch to batch as RPMs increase above ~3500RPM? It can't be because there's less time to inject with batch fire...



They dont drop SFI? unless you have a snippet of code showing SFI becomes batch?

Blacktree JUL 24, 06:23 PM

quote
Originally posted by sleevePAPA: They dont drop SFI? unless you have a snippet of code showing SFI becomes batch?


I don't have a bin file to dissect for you. But yes, GM SFI switches to batch fire above 3000 RPM.
ericjon262 JUL 24, 07:15 PM

quote
Originally posted by Blacktree:

I don't have a bin file to dissect for you. But yes, GM SFI switches to batch fire above 3000 RPM.



I know a couple of people who looked into the code to confirm this and couldn't find anything to support that, maybe they were looking in the wrong place, IDK, but to me it sounds like a waste of bandwidth and adds to complexity.

------------------
we're in desperate need of a little more religion to nurse your god-like point of view...

Built not bought... Because bolt-ons don't.

http://www.fiero.nl/forum/Forum2/HTML/119122.html

sleevePAPA JUL 24, 08:42 PM

quote
Originally posted by Blacktree:

I don't have a bin file to dissect for you. But yes, GM SFI switches to batch fire above 3000 RPM.



Yeah you guys are right, my bad!
Will JUL 25, 10:01 AM

quote
Originally posted by sleevePAPA:

batch fire(single injector driver ECMs) fires the injectors twice per 2 revolutions(720*), sequential each injector once per 2 revolutions. So batch firing injectors have roughly half the time to fire before they are static. If you look at the vid I posted above, just looking at the realtime data, the PW is ~9.41 ms at 6100 rpm. Thats why the WB goes rich, the injectors are static. Now if I was using the EEC with sequential injector firing, it would be ~55% roughly.




Sequential using a Shelby computer.

6000 RPM = 100 RPS = 10 ms per revolution.
Say it takes 1.5 ms to close and reopen the injector.
With TWO close/open sequences per cycle, the batch fired system spends 3 ms per cycle closing/opening the injector. The resulting on time is 17 out of 20 ms or 85%.
A sequential injector that spends 1.5 ms closing and reopening the injector will spend 1.5 ms per cycle doing so. The resulting on time is 18.5 out of 20 ms or 92.5% duty cycle.


quote
Originally posted by Blacktree:

I don't have a bin file to dissect for you. But yes, GM SFI switches to batch fire above 3000 RPM.



I think this is the result of a terminology mixup.

At idle and low RPM, a sequential system fires the injector in synch with the intake valve.
As engine load rises, the injector on time becomes greater than the intake valve open time. With 240 degrees overall duration, the intake valve operates on a 33% duty cycle, so it doesn't take much load for the injector DC to exceed this.
So once that happens, the sequential injectors spray the back of a closed intake valve just like batch fire does.

However, I'm pretty sure the computers do NOT actually revert to the previous batch fire algorithm, for a couple of reasons:
A) Code complexity - Why program the transition if you don't have to? Such a change in fueling algorithms would also create a border in the table that would require additional calibration time to smooth.
B) Reduction in available max duty cycle as outlined above - GM wants to run the smallest injector they possibly can. Sequential lets them run a 7% smaller injector.
lou_dias JUL 25, 07:23 PM

quote
Originally posted by Blacktree:

What you need to do is trim the fuel at lower RPM and increase fuel at upper RPM. Not to be rude, but fiddling with fuel pressure and BPW vs Volts isn't going to accomplish that.

The most direct route to address that problem is to adjust the VE tables. For starters, you could play with the VE Adder vs RPM table and see if that helps. Reduce the VE values from 4000 RPM on down, and increase the VE values from 4400 on up.

And to address the bogging on take-off issue, go to the AE Async Pulse Multiplier vs Coolant Temp table and reduce the values across the board.

Best of luck. And if you need any help with the programming, let me know. I also have TunerPro, and run the $A1 code mask with my 3.4 V6.


I can't seem to find these exact table names in Tuner Pro's A1_v5.xdf... Can anyone help me out?
lou_dias JUL 26, 06:22 PM
This is what I found and doesn't quite match Blacktree's names:
sleevePAPA JUL 26, 07:09 PM
Accel enrichment should be in there somewhere ill look when i get home

[This message has been edited by sleevePAPA (edited 07-26-2013).]