FOLLOW UP: I have now
confirmed that O2 sensor position in the exhaust does have an impact on the ability to engage lean burn. Immediately after swapping my exhaust manifolds my lean burn functionality returned (indicated on the ScanGauge).
The problems created by moving the primary sensor downstream:
1. Stalling/sputtering/loss of power while accelerating (because of EGR, the ECU is looking for feedback instantly but the delay created by moving the sensor creates the issue)
2. Sputtering/loss of power when going into lean burn. When conditions were met for lean burn it would sputter/cut out and then I felt it kick back out of lean burn and return to normal A/F ratios. It would try repeatedly but fail to ever stay in lean burn
I can also say that the EGR system, while it is a part of reducing the emissions created by lean burn, is not required for operation. I have a faulty EGR valve, and a symptom of it is sputtering under engine load while driving. To correct it I disconnected my EGR valve and the symptoms go away, but I still have lean burn functionality. Although I will add in that EGR enhances lean burn operation and overall fuel economy, so it's best to keep it working. I just need to buy the $200 valve to fix my issue.
Quote:
Originally Posted by cbaber
I've not been able to confirm that O2 sensor position is a factor. As I posted earlier, I swapped my stock exhaust manifold for another Civic setup, which the O2 is at the back of the manifold near the firewall. Even with that setup I could still engage lean burn. My problem is the O2 sensor. Shortly after making my earlier posts my factory sensor went bad, and I bought a cheap replacement. After buying the replacement I can no longer engage lean burn without the engine hesitating and stumbling when it tries to engage.
I've bought another manifold that moves the O2 sensor back up next to the exhaust ports, but have yet to install it. If that solves my problem then I will report back. If not, it's my cheap O2 sensor that cannot handle the lean burn.
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