PDA

View Full Version : Active Fuel Managment Strategies?



JAY4SPEED
November 20th, 2008, 10:30 AM
What would be the best strategy for keeping active fuel management (displacement on demand) less sensitive at highway speeds @ 65 - 70 mph on a stock truck? In particular I'm using OS 12617631 and Cal 12617630 on a stock '08 Avalanche w/ 3.73 gear and stock height tires. Customer wants his AFM (4cyl mode) to stay in longer at highway speeds. I've lowered B0921 to B0936 and raised B0941 to B0960 to open the RPM operating window so that AFM doesn't kick out due to RPM. I get confused on table B0950 AFM Enable Min Vacuum and B0951 AFM Disable Min Vacuum. On B0950, do I understand it correctly that the area under the plot line on this table AFM will allow AFM to be enabled making this plot line the "ceiling" of AFM and if we cross the plot line to the area above, AFM will be disabled? On B0951 the area above the plot line will allow AFM to be enabled and if it value drops to the area below the plot line, AFM will be disabled, making this the "floor" of AFM?

I've tried to raise B0950 and lower B0951. I've attempted to log kpa vs RPM but have inconclusive results to see what is kicking me out of AFM. It seems at speeds of around 70 mph the slightest throttle position movement will kick it out of AFM no matter how big the window may be. Has anyone had success with enabling AFM for longer at highway speeds? Are there more tables than we have access to that affect AFM kicking out?

Thanks in advance for any help.:)

Jay

vortecfcar
November 21st, 2008, 07:06 AM
Try bumping the max TPS to 9% or so.

Nick

JAY4SPEED
November 21st, 2008, 04:37 PM
Try bumping the max TPS to 9% or so.

Nick

B0960? I currently have it set at 50% and still no joy.:bangin:

GAMEOVER
November 24th, 2008, 12:29 PM
I have it set at 12% and I focused on the Vacuum between rpms 1700 & 2300 in 4th gear. I lowered the Vacuum till it would enter 4 cyl.mode at 70-75mph. It works great on the freeway but in town it really sucks because it would always be in 4cyl mode. So I use that setting for highway cruising only and disable the 4cyl.mode in town:) I actually get better MPG with the AFM disabled in town....weird!!!

GAMEOVER
November 28th, 2008, 04:18 AM
EDIT
I went on a 400 mile trip and my AFM didn't want to activate after I re-flashed my ECM last weekend!!! I re-flashed it, to activate AFM, about 5 different times and still would not come back on:( MPG went from 22 highway to about 16-17 highway

Anyone else have this problem????????

GAMEOVER
November 29th, 2008, 12:34 PM
With EFI Live 7.5.4 I could Disable and Enable the AFM whenever I wanted and with the new EFI Live 7.5.5 I can't.......Anyone have any Ideas???:)

JAY4SPEED
November 29th, 2008, 03:45 PM
Also, the AFM pid {GM.AFM} doesn't seem to work so that you know when AFM is active when logging. In fact I had logging hang issues that I believe may be tied to selecting that pid.

GAMEOVER
November 29th, 2008, 05:36 PM
I also tried a Full Flash...with no luck!

GAMEOVER
December 1st, 2008, 10:11 AM
I'm going to have to switch out the E38 ECM with a stock one I guess....:)

GAMEOVER
December 6th, 2008, 09:50 AM
Why can't I re-activate the AFM?

860
March 26th, 2009, 11:53 AM
did you ever get this resolved?

tblu92
November 7th, 2009, 11:29 AM
If you have disabled the COT (cat overtemp ) system in your tune the AFM will not activate at all--

GAMEOVER
November 7th, 2009, 04:38 PM
did you ever get this resolved?

Yes, it was the COT....I re-enabled it and it worked fine...