Quote:
Originally posted by 3.8TransAM
I already know that u have to have your main VE tables dialed in to near 128, or any other fueling correction will be off the intended target when in open loop. As far as that is concerned i am basically there and covered in that area.
November in the chicago area has lots of cold as u can imagine. Been experimenting with timing, fueling etc , for the cold starting and driveability issues i have been experiencing.
Cold starting has been pretty good for the most part. Only real issue i have their is the rpm flair upon startup where it leaps to 1500-2000rpm and then drops back to where it supposed to be. Starts withing first or second crank of the engine. As long as i can find out how to eliminate the flair there are no other issues.
Driveability when cold leave something to be desired.. Idle quality is not as smooth as closed loop control is and smoothness while accelerating is no where near as nice of a feeling as when closed loop. Have experimented in timing (adding) while cold and have noticed quite an improvement but not sure where to proceed from this point
3 biggest issues that i have now are:
1a) How else to eliminate the startup flair? (outside of dropping the park position steps)
1b) How to make the idle drop down correctly when open cold bfore the iac sets itself? (always hangs up when cold and slowly drops back to place when stopped)
2) Best way to determine timing during open loop cold start conditions? Any general rule of thumb or only trial and error?
3) Best way to determine fueling during open loop cold starts? Which tables are the most appropriate to adjust ? And any general rules of thumb or trial and error as the timing?
Thanks and later
Jeremy
PS trying to make it drive away nice and pretty no matter what the tempature is(lots of cold time in my area for me now) |
Hi, you are into the fun stuff now. A lot of this tuning is by the gut and the nose. Startup flair is by park position. The 'better' ECMs have a park steps vs temperature table. Work with this first. Then if the flair hangs too long, look for a kickdown delay table, or, even a temperature vs steps table (during run).
The smoothness during accel can be tough. Sometimes it takes going leaner, then richer to see what the engine requires.
A lot of times (sometimes?) it is the AE that is too rich. There should be an AE vs temperature table to change this.
I mention nose as that is how I did my idle AFR. When the O2 was happy and the BLM/INT was happy the exhaust was so bad the cats ran for cover. I leaned it out until the idle was still decent but the nose (and the cats!) were OK with it. How lean is it? Can't measure, too much cam. But it works. . .
RBob.
