air fuel ratio's

[qikteg]

background info

- d16a3 engine, 4speed auto
- ram intake, 2" catback
- approx 650-700km of driving per week

due to the amount of travel that i do, and the increase in petrol prices, i want to squeeze every km/litre that is possible.

i've got an old school SAFC lying around, waiting to be hooked up. i can adjust at 5 different rpm set points. i also have a jaycar digital air/fuel display.

questions
- should i still get it tuned on the dyno?
- am i able to tune it using just the air/fuel display?
- what should be the optimum air/fuel ratio in terms of consumption, performance etc
- will i need to have different settings if i use unleaded, premium or 98ron?

sorry for the loads of questions. thanks in advance

[saxman]

without a wideband o2 sensor, the a/f display on it is completely worthless... don't try to tune with it, it won't do you a bit of good.

Honestly, you're really not going to be able to make any gains that way, and you don't really have any mods that justify a significant fueling increase

[qikteg]

true. however out of the factory, the majority of ecu's are programmed to run richer than they should. and going by a dynograph produced by the same engine with similar mods, its tending to run quite rich at the high end. and because i do a lot of freeway driving, it means that i'm in this zone quite frequently

[saxman]

most dynos show a/f at higher rpm at higher load... fueling is different at higher rpm and light load.


What sort of a/fs are these dynos showing?

[qikteg]

mind you, this is all based on an assumption that this is how all d16a3 engines perform. of course, i won't know how mine is running until i get it on the dyno

courtesy of fat_85_civic's civic with a d16a3
http://www.redpepperracing.com/gallery/d/149073-2/Stock+Dyno.jpg

[saxman]

wow... crazy rich indeed...

I have a very difficult time believing that that's how honda intended things


for reference sake, if that's how it should be, your a/f ratio will not be like that whille at the same speeds/rpm if you're not giving it full throttle

[qikteg]

yeah, i doubt that honda would have planned for it to run like that. but either way, its something that needs rectifying. i'll get my car dyno'd, using a wideband o2 sensor. that'll confirm wats going on with my air fuel ratio's

[BananaBoat]

Something is definately astray there, without knowing what the owner has done to that car (ie what ecu, mods etc), all comparisons are really useless.

[qikteg]

the engine on the dyno is stock, aside from a k&n panel filter

[BananaBoat]

yeah, and what engine manaement is he running, including add ons(Vafc), vtec controllers etc etc

[qikteg]

d16a3, 1.6l DOHC non-vtec. no engine management upgrades, no add-ons

[BananaBoat]

very strange, i'd put that one down to a bad O2 sensor

[qikteg]

what sort of fuel ratio's should be aimed for?

approximately