Quote:
Originally Posted by oldtamiyaphile
Most petrol cars will run open loop (rich) after a restart, which may be enough to counteract any gains from short P&G cycles.
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Not sure about all cars, but my O2 sensor is warm enough to run closed loop within a few seconds of restart if my engine is hot. Also, closed loop does not necessarily mean rich. The ECU will still target an AFR of 14.7:1 at low loads, but may be a bit rich if the MAP or MAF scaling is off. There are also post-start enrichment tables. For my for my car, post-start enrichment only lasts for 5 seconds and injects 2% extra fuel during this period (with coolant temp over 80 degrees C.) The extra fuel will be really minimal, even with shorter P&G cycles.