Lv8
Thread Starter
Supreme Member
Joined: Jan 2003
Posts: 2,133
Likes: 4
From: Houston, Texas
Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77
Lv8
165 ECM AJUL bin
Load variable; (air flow/rpm) * k constant=load
is air flow in gm/sec (mass,) or ft^3/min (volumetric flow)?
Is the K constant for coolant temp in kelvin, if its just a multiplier want is it's value?
Load variable; (air flow/rpm) * k constant=load
is air flow in gm/sec (mass,) or ft^3/min (volumetric flow)?
Is the K constant for coolant temp in kelvin, if its just a multiplier want is it's value?
Moderator
iTrader: (1)
Joined: Mar 2002
Posts: 18,432
Likes: 233
From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: Lv8
Originally posted by rgarcia63
165 ECM AJUL bin
Load variable; (air flow/rpm) * k constant=load
is air flow in gm/sec (mass,) or ft^3/min (volumetric flow)?
Is the K constant for coolant temp in kelvin, if its just a multiplier want is it's value?
165 ECM AJUL bin
Load variable; (air flow/rpm) * k constant=load
is air flow in gm/sec (mass,) or ft^3/min (volumetric flow)?
Is the K constant for coolant temp in kelvin, if its just a multiplier want is it's value?
RBob.
Thread Starter
Supreme Member
Joined: Jan 2003
Posts: 2,133
Likes: 4
From: Houston, Texas
Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77
LV8
Reply from: RBob
Air flow is in mass, grams per second. The temperature of the air is included in the mass flow measurement.
Air flow is in mass, grams per second. The temperature of the air is included in the mass flow measurement.
Moderator
iTrader: (1)
Joined: Mar 2002
Posts: 18,432
Likes: 233
From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: LV8
Originally posted by rgarcia63
And engine speed is in RPM, that leaves the K constant, which is what I really wanted to know.
And engine speed is in RPM, that leaves the K constant, which is what I really wanted to know.
RBob.
Thread Starter
Supreme Member
Joined: Jan 2003
Posts: 2,133
Likes: 4
From: Houston, Texas
Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77
K constant
I found the reference in a Buick Regal Turbo link user's manual, yes I know my engine isn't boosted, and it isn't a Buick.
Excerpts from webpage:
1) "LV8 is calculated from many factors and is used in
determining engine opeating parameters"
2) "It is calculated from (air flow / engine speed) * K where K is a
constant."
I looked at this because I couldn't find it in any of the GM 1227165 ECM's documentation, or web searches, but in trying to find the webpage where I found the above formula, I also ran across the formula for the 165' ECM which has no multiplier "K" just (air flow / engine speed) as you had said.
My method of understanding is by doing the calculation myself and I can't calculate the airflow using the (air flow / engine speed)=load formula.
Rewriting formula to solve for flow (air flow=load * engine speed.) doesn't give an acceptable value for gm/sec.
What I missing, and or doing wrong?
Excerpts from webpage:
1) "LV8 is calculated from many factors and is used in
determining engine opeating parameters"
2) "It is calculated from (air flow / engine speed) * K where K is a
constant."
I looked at this because I couldn't find it in any of the GM 1227165 ECM's documentation, or web searches, but in trying to find the webpage where I found the above formula, I also ran across the formula for the 165' ECM which has no multiplier "K" just (air flow / engine speed) as you had said.
My method of understanding is by doing the calculation myself and I can't calculate the airflow using the (air flow / engine speed)=load formula.
Rewriting formula to solve for flow (air flow=load * engine speed.) doesn't give an acceptable value for gm/sec.
What I missing, and or doing wrong?
Moderator
iTrader: (1)
Joined: Mar 2002
Posts: 18,432
Likes: 233
From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Understood. The K is a constant that is a calibration term. In the BUA (a $32 mask bin) it is at location $C69A, right before the MAF scalar tables. Here is the location, commments and stuff:
It isn't easy to just plug the numbers into a calculator and get an answer. There is all kinds of scaling going on in the code. If it helps the following is a moderately commented section of the code that does the conversion from gms/sec, RPM, and K to LV8.
RBob.
Code:
LC69A: FCB 80 ; Ld VAR FOR SCALING LV8 SCALE FACTORS ; CAL = arg + 64, (16)
RBob.
Code:
;------------------------------- ; ; Calculate the LV8 term ; ; BUA ;------------------------------- LDX L0095 ; Current Minor LP Ref Period BRSET L0034,$80,LD77B ; BR IF b7, engine RUNNING flag ; CPX LC357 ; Crank RPM lmt BCS LD77B ; ; LDX LC357 ; Mult'cnd to X, (Crk RPM lmt ; ; Go do 16 * 16 Mult ; LD77B: LDD L00EA ; Gms/Sec Disp Value, (Mult'plr) JSR LF2F0 ; 16 * 16 Mult routine ; PSHB ; Save Middle 2 Bytes of Product PSHA ; Save Middle 2 Bytes of Product ; ; ; create one & two delayed LV8's ; LDAA L0063 ; FILTERED LD VALUE (LV8) LDAB L0061 ; one delayed LV8 (for two delayed term) STD L0061 ; L0061 is one delayed, L0062 is two delayed LV8 ; ; mult result if above calc by scalar term ; TSX ; point to middle 2 bytes of prev calc ; LDAA LC69A ; Ld VAR FOR SCALING LV8 Scale factors ; 80d = 80/64 = 16 JSR LF472 ; FACTOR IN 8x16 MULT LDD 0,X ; get result of 8x16 mult ROLB ; ROLA ; BCC LD798 ; LDD #$FFFF ; ; LD798: ASLB ; ADCA #0 ; ROUND ; PULX ; stack clean up ; BCC LD7A0 ; bra if no ovf of adca LDAA #255 ; USE MAX VAL ; LD7A0: STAA L0063 ; FILTERED(?) LD VALUE (LV8) ;------------------------------- ;-------------------------------
Trending Topics
TGO Supporter
Joined: Aug 2001
Posts: 1,008
Likes: 0
From: NJ/PA
Car: Yes
Engine: Many
Transmission: Quite a few
Hi, bringing this back from the dead for some info.
Rbob, can you please explain in more detail what is happening with this snippet of code for calculating LV8? I'm trying to decipher the assembly, but its losing me pretty quickly.
This is for general tuning doc for 32B, MAF, to show how LV8 is calculated, something I wanted to put together along with what a few others are doing, in this threard in the DIY PROM section:
https://www.thirdgen.org/techbb2/sho...hreadid=257513
thanks!
Rbob, can you please explain in more detail what is happening with this snippet of code for calculating LV8? I'm trying to decipher the assembly, but its losing me pretty quickly.
This is for general tuning doc for 32B, MAF, to show how LV8 is calculated, something I wanted to put together along with what a few others are doing, in this threard in the DIY PROM section:
https://www.thirdgen.org/techbb2/sho...hreadid=257513
thanks!
Thread
Thread Starter
Forum
Replies
Last Post
Jim85IROC
DIY PROM
3
Oct 2, 2003 11:50 AM
