Quote:
Originally Posted by old jupiter
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.
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An intake charge isn't richer due to additional fuel being adding when exhaust gases are added, unless for whatever reason the manufacturer can't get it running smoothly and has to add fuel, but that sounds more like a engine config specific thing.
Quote:
Originally Posted by jtbo
One thing is bit puzzling, hotter burn = cleaner burn, this is what we are being taught here, but I did read that EGR lowers burn temperature, is this case again one of those were one parameter is lowered in expense of others?
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That depends on what you mean by hotter burn. A weak spark on an SI engine or poor atomization from an injector on a CI engine is bad for emissions, but at the same time if the combustion reaction is too hot that's also bad for emissions.