bigaaron said:So you are saying that fuel cut is ONLY because of too much intake air? That is not correct. What if he was hitting fuel cut because the fpr was disconnected? What if he was hitting fuel cut because he had a big boost leak? What if it was running too rich because of incorrect afc settings? There is a lot more to it then you are implying. And furthermore, the ecu triggers the fuel cut because it can not supply enough fuel for the air metered going into the engine (injector duty cycle maxed out) , so if he gets a maft he still has the problem and still gets fuel cut.
Running too lean will not trigger fuel cut, the ECU isn't smart enough for that (what a shame too...what a life-saver that would be!). I have run too lean. A good example...... I was diagnosing a vacuum leak some time ago, and in troubleshooting I decided to plug all vacuum ports.....absent-mindedly including the one going to my fuel pressure regulator. No FP increase with boost (16psi), NASTY detonation, but no fuel cut.
The function behind the Lex AFM changing the point where fuel cut happens is *entirely* because the ECU believes there is less air. (NOTE: this isn't to say more values don't contribute to when & where FC happens, but that Karman frequency is a very LARGE factor)
If you're hitting fuel cut and drop in a Lex AFM and do nothing else at all, you'll run deathly lean, but you'll stop hitting fuel cut. (for the kids watching at home: "deathly lean" means "don't do it")
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