Getting the most out of lean burn (Honda)

[Jakins]

So you are doing a tps resister so the Ecu will think you are always in range? Ok to recap... Give it like 40% throttle for a split seccond and let off? And keep it below like 36 percent? And what does the shif light indicate? Is that telling you are in LB even if you shift before it? And lastly, do you think headers would help to keep your EGT's down? How do the vx and HX like those? Because I'm thinking my cat is seriously clogged.

[greasemonkee]

I don't know how the HX engines operate, but for the VX getting back into leanburn after heavy load is a matter of letting off the throttle and getting back on it. I don't know what the shift light is indicating other than optimal shift points.

TPS bypass is for leanburn in idle.

Headers may help to some marginal degree for more efficient power production, probably not worth the cost unless your'e going all out.

EGT's are no concern with what were doing, I only mentioned it because its a direct indication of why leanburn is more efficient than shoichiometric burn.




Mileage on the first controlled tank was 58.3 on my WNC mountain route. This is up about 1.8 mpg from previous weeks, but it was also cooler tonight which must be taken into consideration. I believe the current mods yielded a solid 2mpg gain, but will have a more solid number in a few days. I'm still working on the final mod. 60mpg+ on the mountain run will be easy to hit once the fuel sucking tires are replaced.

...And for what it's worth, I'll probably be selling the fuel controller and using a $2 variable resistor to accomplish the same thing.

[greasemonkee]

Update -

Goal #1 and #3 have been achieved, #2 was becoming more complex than it was worth - the fuel cut is disabled if the ecu sees an off-idle signal so the revs would drop too slow during shifts. Also, any additional load (headlights, turn signal) bogs the engine running leanburn that low and since there's no idle air control valve working the engine is purely at the mercy of an axillary air source for rpm control, that would take far too much time and funding trying to create a system to maintain a stable idle. What has been done thus far is about 90% of the gains to be had so this is where I'll conclude the project. The 60mpg barrier on my route average will have to be accomplished with aero mods, tires, wheels, and caps are next - 2mpg to go.

Achieved:

Leanburn in neutral and stationary while throttle is depressed

Leanburn in 1st gear

Leanburn in all gears (rather than 5th only) at cool engine temps - engages about 1 mile sooner than before.

Leanburn at/near ambient manifold pressure

More usable torque in leanburn

VTEC does not engage until 3000 under any condition

Max power air/fuel ratios can be held at 13.5 for optimal efficiency.

A solid 2mpg gain.

----------------------------------------

Added parts - Apexi fuel controller, ebay square wave generator


-------------------------------------

Leanburn idle

http://s12.photobucket.com/user/grea...606d9.mp4.html




Ambient manifold pressure leanburn

http://s12.photobucket.com/user/grea...9efec.mp4.html




More efficient air/fuel ratio under high rpm/high load

http://s12.photobucket.com/user/grea...d9905.mp4.html

[Jakins]

great job brother!

[WD40]

greasemonkee:
Sounds great .. But can you please explain how and what you did in layman's terms, maybe add a few pics and a parts list.
I would love to be able to replicate what you did but I don't understand how.
Thanks Dennis

[greasemonkee]

This is the best I can break it down:


Here's the pulse generator - New NE555 Square wave signal generator 1hz-500khz | eBay

It's not perfect, but does the job. This makes the ecu think the car is rolling at 60 mph, to the speed lower the board would need to be modified, doubtful it would make a difference anyway. The jumper must go in the 50 Hz to 1Khz slot and the frequency turned down to the lower end of the adjustment - frequency and duty cycle should really should be matched up to the waveform of the stock VSS with a scope, but you might get lucky and hit the sweet spot.

*Signal line - Intercept the VSS signal to the ecu, that is pin B10 (yel/blu). Cut that line, cap the side going back into the harness and feed the output signal of the pulse generator into the ecu.

*12V+ can be found at A25 or B1 (yel/blk)

* Ground can be found at A23 or A24 (blk)

Solder the lines to the pulse generator, grab a small project box from radio shack, and stuff some foam around the board to secure it.

Now you've got leanburn in any gear, when stationary with the throttle slightly depressed, and at lower coolant temps.

NOTE: fast idle is always active and might kick up the idle a hair, add a toggle switch in the VSS line if necessary.


----------------------------------------------


Removing MAP signal may be as easy as using a resistor in the map signal line, but the better way would be to grab an Apexi SAFC, VAFC, VAFC2, or NEO. The older non-vtec version should work fine, they often go for $100-$150 on craigslist or ebay. This way you have more control over rpm and throttle position over how much fuel you're pulling.

Be aware that the more fuel you pull, the more timing you add, also the timing curves get more out of whack so use with caution and listen for detonation. My settings wound up at -8% fuel and 12* distributor timing. The oxygen sensor will add fuel as needed to compensate so increasing the fuel pressure is not necessary.

[WD40]

Thanks .. ordered the pulse generator

[slownugly]

Do you have any mpg numbers before and after these mods?

[HydroJim]

How is the apexi unit installed?

[ever_green]

Originally Posted by greasemonkee

Just for the record - here's a quick and crude vid I shot on the route to establish a baseline for the leanburn limits.

thanks for the vid. i don't drive a civic but i have done a similar ecu tune for mpg on my impreza to run extra lean in closed loop. it pays off over time for it self.