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brucepick · 10-24-2009, 09:27 PM

I'm pretty sure that if you use custom ECU programming like MegaSquirt you can map your own rich/lean ratios. But you have to be pretty smart about it - too lean and you'll burn valves etc. I bet it can be done though.

The Honda Civic VX and the later Civic HX ('96 - '05) both had lean burn capabilities coded into their ECUs. I think some of the later Hondas also had/have lean burn but I can't say which ones for certain. I think Insight Gen 1 and Civic Hybrid?? Maybe others??

My own thinking is that lean burn lets you get max power out of a given qty of fuel because you're not sending a percentage out the exhaust unburned. Standard stoich ratio leaves some unburned fuel in the exhaust deliberately to keep the cat converter temp up - it combusts in the converter. The lean burn Civics keep the cat temp up by having the cat in the exhaust manifold (at least that's what my HX has) so it tends to stay pretty hot.

10-24-2009, 09:27 PM	#2 (permalink)
brucepick Hypermiler Join Date: Dec 2007 Location: Eastern CT, USA Posts: 1,076 Lean Burn Civic - '97 Civic HX Team Honda 90 day: 51.96 mpg (US) Thanks: 78 Thanked 87 Times in 63 Posts	I'm pretty sure that if you use custom ECU programming like MegaSquirt you can map your own rich/lean ratios. But you have to be pretty smart about it - too lean and you'll burn valves etc. I bet it can be done though. The Honda Civic VX and the later Civic HX ('96 - '05) both had lean burn capabilities coded into their ECUs. I think some of the later Hondas also had/have lean burn but I can't say which ones for certain. I think Insight Gen 1 and Civic Hybrid?? Maybe others?? My own thinking is that lean burn lets you get max power out of a given qty of fuel because you're not sending a percentage out the exhaust unburned. Standard stoich ratio leaves some unburned fuel in the exhaust deliberately to keep the cat converter temp up - it combusts in the converter. The lean burn Civics keep the cat temp up by having the cat in the exhaust manifold (at least that's what my HX has) so it tends to stay pretty hot. __________________ Check your tire pressure - keep it up !! We've learned that diet has a closer relationship to cancer than we ever thought. Please see this Wikipedia article on The China Study. Driving Lean Burn '97 Civic HX, lotsa mods by now! '89 Volvo 240 is semi-retired. I did love that car though!