Why am I suddenly running lean at idle?
Thread Starter
TECH Fanatic
Joined: Feb 2004
Posts: 1,259
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From: Lexington, KY
Why am I suddenly running lean at idle? I have been working on my tune for a while with EFI live and a LC1 wideband. I have done 3 passes of AutoVE for "normal" driving and the AFR has been pretty much dead on at 14.63. I have not yet worked on PE or WOT tuning. I have been working on getting all of the surge out of it first, and making some good progress. Tonight I spent a couple hours working on the throttle cracker and decay. Without changing anything but the TC and decay, it suddenly started running lean at idle, between 15 - 17, with some spikes to 19. And I've started to pick surge back up in areas where I had it tuned out. So I don't think it's the WB but I guess it's possible. When I pull up the BIDI controls and command it at 13.5, it only drops down to about where it should be 14.5 - 15.5.
Does anyone have any idea what is going on and how I can get it back besides AutoVE again? Or do I need to do this if I add a bunch of air to the TC anyway? I can't see why but I'm still learning and could use some advice. My drivability has improved greatly and I don't want to take (another) step in the wrong direction.
Thanks in advance.
Dave
Edit: I'm still running closed loop/SD by the way.
Does anyone have any idea what is going on and how I can get it back besides AutoVE again? Or do I need to do this if I add a bunch of air to the TC anyway? I can't see why but I'm still learning and could use some advice. My drivability has improved greatly and I don't want to take (another) step in the wrong direction.
Thanks in advance.
Dave
Edit: I'm still running closed loop/SD by the way.
Sounds like some of my tuning experiences lately...I have ordered a new sensor as I think I was chasing my tail. I finally started listening to the engine and said to heck with the sensor until I get the new one.
With headers the wideband and the narrowbands may diverge
at low exhaust flows because the wideband is heater-controlled
and the narrowbands are hope-the-heater-works. Was the
weather colder than before? External changes can't be ignored
especially with a speed density only setup. The IAT (and its
realism) factor into it strongly, especially as it swings away from
where you initially tweaked it up.
at low exhaust flows because the wideband is heater-controlled
and the narrowbands are hope-the-heater-works. Was the
weather colder than before? External changes can't be ignored
especially with a speed density only setup. The IAT (and its
realism) factor into it strongly, especially as it swings away from
where you initially tweaked it up.
Thread Starter
TECH Fanatic
Joined: Feb 2004
Posts: 1,259
Likes: 0
From: Lexington, KY
It was colder when it went lean than it was when I did the VE table, so maybe it is the weather. I thought as long as I was running closed loop it would adjust even if the maf wasn't hooked up.
