Quote:
Originally Posted by blsfrs
Are you sure about that? It's a pressurized system. That's why it make bubbles when it leaks. I don't see how any air comes into the system then travels upstream to the 02 sensor especially at higher rpms.
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Take a look at this brief but simple explanation (scroll down to the paragraph explaining the basics of gas reversion)
https://nasaspeed.news/tech/engine/t...-of-an-engine/
If there's a leak, it will introduce additional oxygen into the system, and due to reversion, that oxygen will travel all the way to the primary/AFR O2 sensor thus fooling the engine thinking it's running lean.
Had this issue back when I was still NA. A very small leak at the overpipe/header connection (the other connection points, especially the header-engine were sealed/leak-free) produced an LTFT value (at idle and low throttle input) of around 14-16%:
High RPM - Low throttle:
https://datazap.me/u/boccaccio/41020...21&tmax=220.90
IDLE:
https://datazap.me/u/boccaccio/idle-...log=0&data=1-8
Reason was a slighlty warped Overpipe flange (AVO 2.5" ceramic coated overpipe).
Replacing the gasket (used the thick graphite Remplex gasket) solved the issue and brought the LTFT into the +-3% range.