A lean running engine runs hotter, use less fuel?

[Cdubneeddeal]

Since this thread has spiraled way off topic: Lean engine does mean it's using less fuel but running lean is very bad for your valves and pistons. If in doubt run rich. At lower RPM's you'll notice some power loss but you'll notice more power at higher RPM's.

 

[iamwiz82]

Originally posted by: shabby

Originally posted by: jagec

Originally posted by: zerocool84
When in doubt run rich.

Especially with forced induction.

Except for the new direct injected turbo engines, they can run super lean compared to regular fuel injected ones.
My solstice gxp hovers at 14:1 till 4000rpm then dips to 12.7:1 until the rev limiter. At first i couldnt believe it but thats the commanded afr the ecm wants.

That's pretty much a standard AF mixture, from my dabblings in aftermarket forced induction.

 

[Uhtrinity]

Originally posted by: Eli

Originally posted by: Uhtrinity
Honda has been using lean burn technology since the 90'2. On my Insight I can usually see when the ECU puts the car into lean burn mode. When on a flat road below 70mph you let up on the accellerator, and the Instant mpg guage will jump from the 60mpg range, and spike to 80 - 120mpg, and hold for upto 30 secs, then drop back down for roughly 10 seconds while Nox is flushed from the Catalytic Converter. This will repeat as long as the engine is warm enough and there isn't excessive engine load. Cold weather, a head wind, or an incline will kill lean-burn. There is also a noticeable lack of power when in lean burn.

On a downhill slope it is hard to tell as the mpg meter will peg at 120 - 150mpg. My record downhill was 120 - 150mpg for 60 miles due to the downhill road. That was coming off of Lolo pass, MT, heading towards Lewiston, ID doing 60 - 65 mph.

You can only get lean burn going for ~30 seconds?

I'm pretty sure I've gone at least 10 minutes.. It does eventually kick off, but like you say.. only for 10-15 seconds.

If you're really gentle with the throttle, you can keep lean burn up almost any incline, but you have to accept the decrease in speed.

Unfortunately, I'm too much of a spirited driver at heart and have eschewed that style of driving for a more normal style, and my MPG has suffered as a result, only averaging 52-55mpg.. lol

I'm pretty sure the new ecm update limits the lean burn cycle time, but I am still seeing 65 - 80mpg on long stretches at ~60 mph. The ecm update was the one that addressed the po420 cat converter codes.

 

[Eli]

Originally posted by: Uhtrinity

Originally posted by: Eli

Originally posted by: Uhtrinity
Honda has been using lean burn technology since the 90'2. On my Insight I can usually see when the ECU puts the car into lean burn mode. When on a flat road below 70mph you let up on the accellerator, and the Instant mpg guage will jump from the 60mpg range, and spike to 80 - 120mpg, and hold for upto 30 secs, then drop back down for roughly 10 seconds while Nox is flushed from the Catalytic Converter. This will repeat as long as the engine is warm enough and there isn't excessive engine load. Cold weather, a head wind, or an incline will kill lean-burn. There is also a noticeable lack of power when in lean burn.

On a downhill slope it is hard to tell as the mpg meter will peg at 120 - 150mpg. My record downhill was 120 - 150mpg for 60 miles due to the downhill road. That was coming off of Lolo pass, MT, heading towards Lewiston, ID doing 60 - 65 mph.

You can only get lean burn going for ~30 seconds?

I'm pretty sure I've gone at least 10 minutes.. It does eventually kick off, but like you say.. only for 10-15 seconds.

If you're really gentle with the throttle, you can keep lean burn up almost any incline, but you have to accept the decrease in speed.

Unfortunately, I'm too much of a spirited driver at heart and have eschewed that style of driving for a more normal style, and my MPG has suffered as a result, only averaging 52-55mpg.. lol

I'm pretty sure the new ecm update limits the lean burn cycle time, but I am still seeing 65 - 80mpg on long stretches at ~60 mph. The ecm update was the one that addressed the po420 cat converter codes.

Hmm, that kinda sucks.

I'm still getting intermittent po420 codes. I keep using my scan tool to just turn the light off, lol.... I should take it in and get it taken care of I guess.

 

[exdeath]

Originally posted by: iamwiz82

Originally posted by: shabby

Originally posted by: jagec

Originally posted by: zerocool84
When in doubt run rich.

Especially with forced induction.

Except for the new direct injected turbo engines, they can run super lean compared to regular fuel injected ones.
My solstice gxp hovers at 14:1 till 4000rpm then dips to 12.7:1 until the rev limiter. At first i couldnt believe it but thats the commanded afr the ecm wants.

That's pretty much a standard AF mixture, from my dabblings in aftermarket forced induction.

Forced induction you want to stick around 11.x at WOT and < 20 deg timing, assuming something standard like a 8.5:1 compression ratio.