TPI Tuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
Sponsored by:
Sponsored by:

How is Airflow data calculated / Data logged

Thread Tools
 
Search this Thread
 
Old 08-27-2023, 10:38 AM
  #1  
Senior Member

Thread Starter
 
F-body-fan's Avatar
 
Join Date: Apr 2007
Location: Green Bay, WI
Posts: 917
Received 19 Likes on 18 Posts
How is Airflow data calculated / Data logged

The ECM gives both Air flow gm/sec & MAF gm/sec.

I am wondering what other inputs if any influence the "air flow" data?
At first glance airflow just looks like a duplicate of MAF data , but I am realizing they are different.

Are both of these coming solely from output from the MAF sensor? Or is it a combination of info on the airflow reading?

Is this the dynamic calculation from the ECU's learned A/F tables?



Last edited by F-body-fan; 08-27-2023 at 11:07 AM.
Old 08-28-2023, 07:51 PM
  #2  
Senior Member

Thread Starter
 
F-body-fan's Avatar
 
Join Date: Apr 2007
Location: Green Bay, WI
Posts: 917
Received 19 Likes on 18 Posts
Re: How is Airflow data calculated / Data logged

It appears it has nothing to with learned A/F ratios like I was guessing above. .

I just dropped power to the ECU to reset, & still had the same type of data.



Old 09-03-2023, 06:16 AM
  #3  
Supreme Member

 
SbFormula's Avatar
 
Join Date: Jun 2012
Location: Canada
Posts: 1,239
Received 152 Likes on 125 Posts
Car: '91 Firebird Formula
Engine: SP383 Deluxe FIRST® TPI Intake
Transmission: Tremec T56
Axle/Gears: Moser 9" Eaton Truetrac Motive 3.89
Re: How is Airflow data calculated / Data logged

Hi

Assuming you have a '7165 with $6E mask, TPI system

The MAF sends a voltage to the ECM B12 (0-5volts). The ECM looks-up the voltage in a series of MAF tables. The g/sec returned data was human programed by GM. The g/sec data is used by the ecm to calculate injector base pulse width (INJ BPW) before correction and other adjustments.

INJ BPW = (((((MAF/8)/(RPM/60))*2)/AFR)/(INJ Flow Rate/60/60)*1000/2.20462)*1000/2

RPM is read by ECM from distributor
AFR is programmed data, usually 14.73 in closed loop
INJ Flow Rate is programmed data, usually 22.36 (for 5.7TPI L98)

The ECM has a provisions to return g/sec data in case of MAF failure. Unplug the MAF and try scanning. You should still see g/sec but will get a SES code.

I would not know why your scanner returns 2 sets of data for airflow.



Last edited by SbFormula; 09-03-2023 at 06:26 AM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
ATSAaron
DIY PROM
3
02-23-2014 08:57 AM
Michail
Alternative Port EFI Intakes
2
11-25-2008 06:12 AM
shaggy56
DIY PROM
3
06-28-2006 08:16 PM
blue86iroc
DIY PROM
2
04-28-2003 04:22 PM



Quick Reply: How is Airflow data calculated / Data logged



All times are GMT -5. The time now is 11:37 AM.