Wideband Lost its Mind??? HELP!!
Thread Starter
Staging Lane
Joined: Aug 2007
Posts: 61
Likes: 0
From: East Tennessee
Wideband Lost its Mind??? HELP!! I just finished a LT header install and I'm trying to dial the PCM back in to reflect the new changes. Before the install, I dialed the VE table and MAF with no problems. Now during the tuning process, my scan is showing the wideband is acting very sporadic. I have trouble-shooted as much as possible. I have re-calibrated my wideband, installed a new O2 sens on driver side before cat, checked bolt tightness on header manifold, and re-gasketed the air pump ports. At first I thought it was the LC-1 wideband, but my scan shows the AFR shown by the wideband has the same plot characteristic as the O2 sensors. All three plots have a pretty good 'Saw Tooth' pattern. I also figured this was because the car is 'learning' new trims. Tuning is real difficult since the AFR input to the scanner is hopping up and down and the histo is getting a bunch of erroneous values.. Am I missing something here?? Has anyone had a similar experience?? How can I get my wideband to settle back down?? Can the air pump check valves be bad?? I'm pulling my hair out (and I don't have much of that left 
) THANKS so much in advance!! HELP please!! 
) THANKS so much in advance!! HELP please!! 
Hello,
I am a noob here, but after i installed my comp headers with slip-fit connectors, I was drawing in outside air at higher exhaust velocities causing my LM-1 to read leaner then normal. May not be you problem, but it was and still is mine.
Grim.
I am a noob here, but after i installed my comp headers with slip-fit connectors, I was drawing in outside air at higher exhaust velocities causing my LM-1 to read leaner then normal. May not be you problem, but it was and still is mine.
Grim.
Thread Starter
Staging Lane
Joined: Aug 2007
Posts: 61
Likes: 0
From: East Tennessee
well I flanged my connections and used gasket material between them... I may be sucking air too, but all my flanged connections are downwind of my wideband and O2 sensors. I wonder if it can travel back up the pipe??
TECH Regular
Joined: Aug 2004
Posts: 443
Likes: 0
From: Tyler, TX.
U may check in the programmer of the LC1 program and make sure your not reading lambda instead of A/F. Its pretty common for LC1's to lose there settings over time. And this would cause the wideband to jump around like your narrowbands as well.
The sawtoothing may mean you are still in closed loop.
If so there is too much meddling and the headers can
make the mixture more prone to bury at both ends, and
do so asymmetrically (so whacking all trim-based tuning
schemes.
I recommend you put the closed loop enable temp up
to where it can't go CL, wipe the trims (or disable OL
STFT) and do your tuning based on immediate AFR
error. At least the AFR should be stable enough to draw
conclusions from.
If so there is too much meddling and the headers can
make the mixture more prone to bury at both ends, and
do so asymmetrically (so whacking all trim-based tuning
schemes.
I recommend you put the closed loop enable temp up
to where it can't go CL, wipe the trims (or disable OL
STFT) and do your tuning based on immediate AFR
error. At least the AFR should be stable enough to draw
conclusions from.
Thread Starter
Staging Lane
Joined: Aug 2007
Posts: 61
Likes: 0
From: East Tennessee
I just logged some data today while in closed loop. Attached is the scan and I used the default table setup so anyone should be able to view it. If you are able to take a look look how choppy the O2 sensor voltages are and look how choppy the STFTs are. Is this correct?? I don't remember it being this violent before the LT's. Thanks again for everyones' help!!
