Injector Flow Rate vs (Injector Constant vs Vacuum) MAF code - Third Generation F-Body Message Boards

pfk · 02-25-2008, 02:13 PM

I am making some adjustments to may MAF bin and have a question about the Injector Constant vs Vacuum(VacAFPR) table.

In my SD bin, I purposely fudged the Injector Flow Rate to give me more range with my VE table. Now that I have the VAFPR hooked up, I was going to use the table to put in the actual amounts,obviously it is going to affect my VE table significantly.

so here's the thing

Here's the table with actual values with 90# injectors calculated at 85%DC

0 Kpa 37psi 18.55g/s
10 Kpa 36psi 18.3g/s
20 Kpa 35psi 18.04g/s
30 Kpa 34psi 17.78g/s
40 Kpa 31psi 16.98g/s
50 Kpa 30psi 16.7g/s
60 Kpa 29psi 16.42g/s
70 Kpa 27psi 15.85g/s
80 Kpa 26psi 15.55g/s

In order to keep the VE table usable up to 100Kpa, I had my Flow Rate set at 10g/s (14 was ok but I wanted to leave room for the s/c so I went with more)

What would be the best way to go about this? should I fudge the table to coordinate with the old 10g/s flow rate or should I edit my VE table to match the actual flow rate?

The next question would be is does the MAF code, while running in SD mode due to MAF failure,use the VAPFR table?

dimented24x7 · 02-25-2008, 04:18 PM

The VAFPR corrections where mainly for high winding NA setups that need lots of pressure to keep the PW down at high RPMs. They can be used with the SC setup, but after the MAP maxes out, the tables will flatline at 0 kPa VAC while the FP will keep rising a few PSI as the boost builds. You can likely just work the corrections into the MAF table at high airflows and it will roughly correct for the VAFPR pressure increase. Worst case will be a few % rich at WOT when the boost raises the pressure. The table is used at all times, even during a MAP failure. The n-alpha MAP will be used to approximate the vacuum.

pfk · 05-04-2008, 08:35 PM

I am back at it again with the VAFPR...

I read through the disassembly several times and got all of my sensor data working like I would like it to, in fact, I have gone back and changed it several times since.

I decided to get a different VAFPR so that I know that it will operate properly (the one I was using was made for lower pressures and adapted)

I started back with the stock LS1 MAF table (it does work well as is) and had a discovery that my 90# injectors were in fact 80# injectors. Then found out that the calculator I was using for the flow rates was using a different conversion factor. Changed it to the norm and corrected the flow table to match, but am still having trouble dialing it in.

I added a display for the Injector Flow Rate value so that I can try and decipher what is going wrong, and to my surprise I saw the display go over the highest point on the table.

I have tunerpro grabbing 2 bytes of info at 0257 and displaying it with a factor of 0.000305. For the most part it is working as it should but then at times it is displaying 19.99 :think:

I tried searching through the source code for any place that uses the info at 0257 and 0258, and all I could come up with was

Code:

;-[Gms/cyl fuel] / injector flowrate
;    
    LDD    0,Y            ;Load two upper bytes of fuel/cyl 
    LDX    L0257            ;Load inj flowrate x 3276.8
    FDIV                ;Upper two bytes of gms fuel/inj. flowrate
    STX    4,Y            ;Save result 
    LDD    2,Y            ;Load in lower two bytes
    LDX    L0257            ;Inj flowrate x 3276.8
    IDIV                ;Lower two bytes / inj. flowrate
    XGDX                ;Get result into D
    ADDD    4,Y            ;Add in previous result
    BCC    LFUEL01            ;Bra if no overflow
;
    LDD    #$FFFF            ;Clear overflow

and

Code:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;-Look up the injector flowrate based on vac
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;
    LDAA    L01EC            ;Load kPa vac
    LDAB    LINJP01            ;Filter coeff. for vac used in lookup
    LDX    L01E0            ;Stored vac kPa for lookup, filtered
    JSR    LF0F6            ;Filter routine
;
    STD    L01E0            ;Save updated filtered vac kPa
    LDX    #LINJP00        ;Load injector flowrate
    JSR    LD2D00            ;16 bit 2D lookup
;
    STD    L0257            ;Save it, injector flowrate x 3276.8

I do not see anything that would do anything to the values recorded so once again I'm confused.

I just finished remapping my ALDL xmission table again and will be saving another log shortly, if I still have the same result, I will post a small chunk of it to show what it is I'm talking about.

pfk · 05-05-2008, 01:14 AM

Well I don't know what to say, I guess I must have screwed something up when I made my last changes to the xmission table. After this remap, everything appears to be operating normally.

I ended up removing the vac/boost reference to the vafpr,and doing a run. Everything worked out fine, but I had to change the air flow values again. I was hoping to get the injector flow rate to work so that I could leave the MAF table alone, but couldn't do it. I'll keep going on this bin for a couple of days and maybe start fresh again but at least I have another drivable bin.