[dayidie]

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.