Quote:
Originally Posted by roflwaffle
Kinda.... Provided there isn't excessive EGR and the mixture is homogeneous, just as much fuel should be combusted as w/o EGR.
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Yes . . . because the mixture has been RICHENED somewhat to make up for what's displaced by the exhaust back-filling. One of the frequent causes of mysterious part-throttle surging is a too-lean mixture caused by excessive EGR.
There was always at least a little EGR effect in engines at part-throttle, even before the EGR system was invented, due to incomplete cylinder-filling and exhaust scavenging (especially in engines with cheap and inefficient factory exhaust and intake manifolds. This called for an earlier lighting-of-the-fire using vacuum advance.