What table would cause this problem?
06-05-2006, 10:25 AM
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What table would cause this problem? I have a 99 SS with a 402 LS2 with a pretty big cam. It was tuned by a reputable tuner. Now I'm trying to figure out why it's going lean when I go into third (automatic). The injector duty cycle can be seen going from around 65 percent down to about 50 percent and the o2s fall off as well, but no other sensors I'm logging appear to be changing values to corelate with this change. Therefore I figure it has to be the tuning somewhere in one of the tables that is calling for this leaning out. Any help is greatly appreciated, because I don't want to hurt anything! Thanks, Brian
06-05-2006, 10:43 AM
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If you're still running off a MAf then I'd look at the MAF output. It may be dropping a little in your high gear. Once you get in high gear you are moving less air/time.
06-05-2006, 10:51 AM
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Originally Posted by white2001s10
If you're still running off a MAf then I'd look at the MAF output. It may be dropping a little in your high gear. Once you get in high gear you are moving less air/time.
This is what puzzles me, because the MAF doesn't drop at all when this commanded lean out is taking place. I expected to see the MAF or the MAP to be doing something, but they stayed the same when this occured.
06-05-2006, 11:13 AM
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Originally Posted by 6speeder
This is what puzzles me, because the MAF doesn't drop at all when this commanded lean out is taking place. I expected to see the MAF or the MAP to be doing something, but they stayed the same when this occured.
I assume you have your VSS input working correctly?
You'd see a problem on your datalogs if there was one with the VSS.
Are you running with zero positive fuel trims?
and is your voltage remaining constant?
06-05-2006, 11:23 AM
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My fuel trims are positive, but now that you ask I've noticed that my lights seem to be dimming when I go WOT? My VSS is working great. I just ran the 4l80e output into the old 6 speed VSS input. So as far as the voltage goes, does this sound like it could be a problem?
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06-05-2006, 11:29 AM
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I'd look close at the voltage on your logs. How much is it changing?
Normally the table increases PW when the voltage goes down, and vice-versa.
It's a possibility worth checking into.
Normally the table increases PW when the voltage goes down, and vice-versa.
It's a possibility worth checking into.
06-05-2006, 11:35 AM
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OK, I will! Now is it normal for the voltage to drop at WOT. It's appears as if the alternator is kicking off when I go WOT by the way the headlights get a little dimmer.
06-05-2006, 12:41 PM
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Well....if the lights dim at WOT, then I'd assume the voltage is dropping everywhere else (ie the fuel pump). You might need to re-check ALL of your wiring and grounds.