PCM Diagnostics & Tuning - even if i pull fuel, the trims read the same in this area....




WS6FirebirdTA00
10-08-2005, 11:01 AM
i posted a while back about this. here is the deal. on decel (dfco is disabled) the trims go way negative on my every time i log no matter how much fuel i pull in the ve. ok now i went to the ve and smoothed it out and almost doubled the numbers in the upper left corner, went out for a ride and the trims were -15ish. well with all that fuel taken back out, the trims still are at -15ish. im just afraid to pull out too much fuel in this area and cause issues. with fuel taken out my numbers are in the teens and 20's. can someone comment on this and let me know? thanks


Gman2002Z06
10-08-2005, 04:18 PM
Doesn't increasing the VE values add more fuel, because the PCM thinks you are getting a greater percentage of cylinder fill...

Remember too, that if you are using the MAS, it too plays a part in determining the amount of fuel to add...

Peace...Gman

WS6FirebirdTA00
10-08-2005, 05:47 PM
i dont have MAF just SD, yea increasing VE makes it rich, did i say that wrong? either way the trims go way negative....every time even after i pull fuel, so it SHOULD get leaner not stay rich


bowtieman81
10-08-2005, 08:44 PM
First, does the computer run off some of the idler functions on decel with throttel closed?

Also, with DFCO disabled, do the injectors reach the minimum pulse width on decel?

WS6FirebirdTA00
10-08-2005, 09:05 PM
ill check the log and let you knwo

DellZ06
10-10-2005, 03:51 PM
If I remember correctly, deceleration "generally" maps to FTC 21. Here is my opinion (your original post sparked me to study this):

The values for FTC 20, 21, and 22 are learned between the time when car first goes into open loop and the evap begins to purge (or is done purging, I can't remember off the top of my head -- but regardless it happens shortly after starting the car). Once they are learned, it locks for the duration. Thus, the VE cells that the car is in during your deceleration are NOT the sames ones that FTC 21 was learned in. I would look in your log to see what VE cells they are actually learning in and change those to affect your decel issue.

John.

WS6FirebirdTA00
10-10-2005, 04:04 PM
thanks man im gonna check it now and ill post back