Main Fuel Table near idle VE table in $OD 7427 - Third Generation F-Body Message Boards

patcon · 10-14-2009, 05:34 PM

What determines when the values are used from the smaller near idle VE table. I have seen 2 constants that seem to determine when this table is used. One is the "Max speed for idle fuel table" and "Max TPS for idle fuel". Are they the only two items that control near idle fueling. If they are then the smaller table seems too large, it reads up to 1800 rpms in 200 rpm increments and 100 Kpa. How will you ever get to 1800 rpms before exceeding 3mph or 2.75% TPS, much less 100Kpa? Also when you switch to the Main fuel table off idle does it move to the same cell or adjacent cell (ie 1200 rpm 40 Kpa on the small table directly to 1200 or 1600 rpm @ 40 Kpa on the large table)? I am going to be working on fine tuning idle fueling and am trying to understand how you would datalog certain sections of the small table based on the Max TPS value. Also if the transition from one table to the other is not smooth will that cause closed throttle idle issues? I am also assuming the tables don't stack (ie total) like I have read about some of the older ECM's (ie exceeding 100%)
Thanks, Charles

This ad is not displayed to registered members.
Register your free account today and become a member on ThirdGen!

LoudmouthSS · 10-16-2009, 05:13 PM

I pulled up a random bin and see the max speed is set to 112mph..like its basically saying "ignore this". TPS voltage threshold is set to 1.18 volts which i would assume is fairly realistic..perhaps taking into acount if the converter is flashing at 0mph. Not really sure what the purpose of the idle fuel table really is...first time im seeing it. The table obviously has more adjustment points...200rpm increments v.s the off idle VE tables 400rpm increments. It may drop into this table under light cruising possibly to better fine tune fueling requires...aka mileage and emissions stuff....providing your under the 1.18 volts of my cal. But as you can see, we are coming up with different values between bin ID's. Basically if this were I doing the tuning, i would make changes to to the idle ve and see if it as any effect. I would get idle straightened out then move on to off idle ve tuning. Anything I do to the off idle stuff i would apply to the idle table as well.

patcon · 10-16-2009, 07:34 PM

I don't believe it drops into this table at light cruising or off throttle coasting because there is another constant that moves you out of the near idle table above a set mph (normally 3 mph); unless I am missing something. I don't really know what controls the idle when coasting at say 45 mph. That is one of my problem areas and there is evidently more going on than I can currently see.
Charles

95 4x4 · 10-16-2009, 09:55 PM

Coasting at 45 mph you are using the off idle Ve table not the near idle Ve table .

patcon · 10-18-2009, 01:29 PM

Bump for my first post.
How do you tune the small near idle VE table when so many of the points will never be used do to the other constants pushing you into the larger table? Not cumulative...? Smoothness of transition from table to table...? Need some OD expert feedback.
Thanks, Charles

95 4x4 · 10-18-2009, 08:03 PM

I'am difinately no OD expert , what i do is tune my near idle VE table . Those values from that table i CP them to the off idle VE table an smooth the values . This way going from near idle to off idle their i is not a drastic difference . Here is a shot of my near idle VE table in graph , hope this helps you .