I've read the older threads on emissions, including one thread where PlatinumWRX dropped to a 87 octane / 91% isopropanol mixture to pass testing. My questions are still unanswered though, so I'd appreciate any info:
What is the effect of ethanol on NOx? How about HC?
What is the effect of isopropanol on NOx? How about HC?
If a vehicle's EGR is functioning and it seems the cat may be marginal (NOx is just over the limit and the EGR is tested OK), will adding either ethanol or isopropanol to the fuel reduce NOx? Will either simultaneously increase HC or other emissions? Any ratios recommended?
Motor is Toyota 5S-FE and must meet CA 93 emissions.