Vtec e leanburn pointless?
 

I had a d15b vtec e for a few months. I found it very annoying to try and stay in lean burn. lean burn did not allow me to plan for hills and take hills in an efficient manner. It would drop out of lean burn then the car would take off so I'd back off the gas then lean burn would cut in again and the car slow down quickly again requiring more throttle and the process would repeat.

My car had no fault codes present and appeared to be running right. The car was a domani, aerodynamics are poor compared to an eg vxi hatch and also heavier by about 100kg

My solution to lean burn..
Once I put a variable resistor on the coolant temp sensor and made the car think the coolant was just a little to cool for lean burn. The car became at least 10% more economical and much nicer to drive.

Has anyone tested the actual fuel consumption of lean burn vs non lean burn by crudely, like I did, switching lean burn off and holding a constant rpm and throttle to get a simple comparison. This type of test wouldn't account for the real world of infinite variables but would give an indication of lean burns real value.

lean burn was never designed to stay engaged all the time as in going up hills when you need more power. id say its working properly.
also i have done a check between lean burn and not. just disconnect your 02 sensor. i got around 40mpg when i did this.

The best way to abuse lean burn for mpg is to use it in combination of pulse n glide technique. You use lean burn to extend your coasting once you hit your target speed. In many cases you wont be able to maintain your speed, but if you allow it to bleed off you can and do so til your bottom speed. Now the trick is to combine this in synch with hills, grades, etc.

Lean burn should be as common today as VVT. With 40 years as a learning curve (remember Chrysler had lean burn cars in the 70s, with noted FE returns), this could be a huge driver for saving folks fuel with bloated fuel prices and a huge balance of payments problem vs. those oh so friendly folks in the Middle East. Fracking will only go so far.

But the hippies bellyache when the emissions are too high. Then they complain that due to emissions, the FE has to drop. Ironic that lean burn was killed by the very people who to this day lobby for better FE, and indeed urged higher FE standards for automobiles, which I argue led to the rise of the SUV's popularity. Perhaps they should be schooled in combustion theory and then decide what is important?

so wouldnt being more FE mean less emissions???

Lean burn has issues with increasing NOx emissions, which is a pretty nasty thing that causes smog and acid rain. The rest of the emissions are likely lower due to the increased efficiency.

how is this possible? it gets better mpg so its using less fuel. less fuel is less emissions. is there a listing some where showing what each cars emissions are?

Burning a lean mixture causes high combustion chamber temperatures, which is good for efficiency, but NOx is created at high temps. Its just a side effect of lean burning.

Here is a general chart made by Toyota that shows how emissions change based on air fuel ratio:

http://ecomodder.com/forum/attachmen...1&d=1403617563

This is why its hard to hold lean burn as the ecu has a purge cycle built in to try to keep the smog in check. I believe the engine engines like the one in the Fit, Insight and other honda vehicles run leaner vs having a mode to give better over all fuel economy and lower end torque.

I remember driving a late 70s Dodge that I was considering at the time. Think it was the 360 or 318 with lean burn set up. For a v8 it was slow as a turtle as most cars of that era were. I don't recall the advertised mpgs as being anything special.

Pre efi, Ford had a variable Venturi carb, 2, maybe even a 1 barrel. My neighbor had one and he always complained it never ran right and the mpg wasn't any better than a regular carb at the time.