[urq] EFI + MAC-14 maxing ataround 5k RPM

QSHIPQ at aol.com QSHIPQ at aol.com
Wed Oct 24 16:40:15 PDT 2007

IIRC Cody, the older EFI designed systems defined Alpha-N for the  changeover 
from MAP to TPS to accomodate big lumpy cams, ala race car,  because the MAP 
signal was unstable.  The newer EFI systems use MAP/TPS/RPM  3D tables for tip 
in transient response and fueling.  As I haven't had  the pleasure of playing 
extensively with MS, I will assume it uses the standard  MAP v RPM tabling 
you describe.  Unless Ben is running a 272 cam, this  shouldn't be an Alpha-N 
type problem.  
Not having the same tables to stare at, I'd take a swag that the injector  DC 
should be 50% or less with 'just' a run to 5k without load.  Maybe I  misread 
what Ben put forth, but I swear I saw 100% DC mentioned.
If it's MAP vs RPM, and MAP is programmable, maybe a rescale is in  order.  
Also, IMS, Ben if this is an automatic MAC 14 computer/harness,  there is a 
jumper wire that needs to be cut off the plug (pin 7 comes to mind  off the top 
of my head) that was a reduced power for first gear launches in the  slushbox.  
I also recall that being a boost only intercept on the WGFV, not  a timing 
retard.  But worthy of a looksee.
Getting a bit far out for a audifans discussion, but Ben, I'd go back to  
seeing what happens to the FPR return flow at 5krpm.  If there is none, you  have 
a more basic problem.
Good luck
Scott J
In a message dated 10/24/2007 12:47:54 P.M. Central Daylight Time,  
cody at 5000tq.com writes:

It's MAP vs. RPM, for true speed density. MAP vs. TPS (called alpha-N) is  
only used on race cars. TPS is only there for accel enrichment, where it gives  
an extra shot of fuel as you open the throttle (like an accel pump on a carb). 
 It's all in the programming.
At any point if injectors are going 100% duty with no load then it's a  
problem with how the tables are tuned or a basic setting issue. The thing is  that 
based on the log file that Ben sent me his injectores are not going over  70% 
duty cycle under full load at the boost level he is currently running. I  
haven't gotten the chance to look at the most recent log file he sent nor the  
settings, but I'll get to that this evening.
-Cody Forbes
_http://www.5000tq.com_ (http://www.5000tq.com/) 


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