Quote:
Originally Posted by turbovr41991
Has anyone ever listed out the lean burn differences between the VX, HX, and insight? From what I can tell with the HX, I can have lean burn all the way to 3,100 rpm.
On a personal side, I struggle to engage lean burn if I am not around 2400 - 2500 rpm, under 20% throttle, under 70 LOD, and on a warm engine. Are these 4 factors what limit lean burn?
I am really interested in this work. I know there are also alot of HX and insight owners that would could benifit from this!
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Haven't driven a VX or HX but my 1st Gen Insight will hold lean-burn up to about 32TPS if you are under 70mph but you need to cut back to about 26TPS to reliably hold lean-burn where it cuts out at 78mph(~2800RPM 5th gear). Cuts out between 85-90LOD depending on RPM and the cars mood that day. Requires 154 degrees or higher coolant temp. I just drove from Minneapolis to Southeast Missouri and holding the 75mpg lean-burn only usually gets you 60-65mpg on the flat with no or favorable wind and temperatures warmer than about normal room temperature. Cooler, uphills, wind, etc and you might struggle to get beyond 55-60 and many hills pull it below 50mph if you don't drop out of lean-burn. There's not much HP at 75mpg. My overal MPG on the way there was 76.1mpg and the trip was 693 miles and took 11hr 15min. 61.6mph average speed.
To get into lean-burn with the Insight you need to drop to MPG meter to about 100mpg, wait about 2 seconds usually but up to 10 depending on the mood of the car. Every mile or so it drops out of lean burn for about 10 seconds to purge the NOx cat and then slinks back in on its own. If you drop out of lean-burn due to TPS sensor, shifting, letting off the throttle, or too much throttle you need to wait about 10 seconds while in lean-burn favorable conditions to get it to reengage at the 100mpg point. With all that being said, it's a PITA to try to cruise above 60mph on the highway with lean-burn with an Insight. Friend drove a leg of a long cross country trip at 85mph and we got 55mpg without lean-burn for a non-stop tank without the lean-burn, don't need it much though since the engine is at ~80% load in 5th gear at that speed.
The Insight seems a bit more complicated to modify its lean-burn considering that it's got more monitoring with the OBDII and is ULEV emissions with the extra NOx cat and lean-burn purge cycles. It seems to make more than just a few factors. Maybe not though, could be easier than I figure.