paulmp3 said:
yea, a standalone with a wideband o2 used to pick desired afr would be great.
tonkabui, i would assume it would adjust for any mods you could do as long as you gave it a desired afr. If you are adding more air, the standalone would add more fuel. Like our stock ecu does in closed loop.
yeah like Paul said...Our stock ECU does it at light loads...the target A/F ratio is set pretty much at 14.7:1...which makes mega good emissions...But we don't have a stock wideband O2 sensor from the factory...and our current sensor (this is only pertaining to the first O2 sensor before the primary catalyst, although the second one is pretty much the same) can only detect changes very close to stoichiometric...and for reasons beyond the scope of this post, fundamentally and engine requires a richer mixture once the load increases...hence the reason ours clicks into open loop...A wide band O2 sensor can detect changes over a much greater scale, and with much more precision...which makes them much more expensive...You can preset a target mixture level, and the engine controller can create the fuel math to get to that mixure in any situation based on the readings of the unburned hydrocarbon content of the sensor...
A quibble with this system can be safety though...by design and O2 sensor only recognizes up to stoichiometric...in which cases only trace amounts of oxygen are left in the exhuast gas...that is the restriction...a 14.7:1 A/F ratio refers to a stoichometric amount of fuel and air for a complete burn (14.7:1 is rounded down...there is never just one molecule of gasoline involved in a complete combustion engine cycle, and there is no such thing as 14.7 molecules of O2...so the number of molecules is rounded down for both proportianetly until the number 1 is in the ratio...This is the reason that most refer to this ratio in terms of "moles" or the total molecular wieght of one molecule in grams... So look at it like 1 "mole" of gasoline, and 14.7 moles of oxygen)...The O2 sensor, narrow band or wide band, usually cannot recognize a mixture leaner than 14.7:1...becuase there are no unburned molecules left in the exhuast...So you can see why that could be bad...The ECU would treat a 14.7:1 mixture no differently than a 20:1 mixture (which could be caused by a faulty injector or large air leak), and not trim in more fuel for safety...All that could cause an expensive grenade...and the problem is that this could occur at idle, in which case the ECU thinks a 14.7:1 ratio is fine, which it is at idle more or less, but anything much leaner than that at any condition is not good...All of this is a problem with closed loop mode in general though, and the same problem could occur while using both Open and closed loop operating
So in some cases hardcore tuners look at high load closed loop as an easy way out...There are some various other sensors incorporated, such as knock sensors, that can prevent catastrophic engine failure with high load closed loop...but since closed loop is a negative feeback system (looks at conditions after the combustion process, and makes changes accordingly...rather than adjusting fuel math before the burn starts)...A lot of tuners regard it as less accurate...IMO it is an easier tuning system to deal with for everyday owners, but for a hugely built racing application Open Loop may be a more accurate form
Sorry for all that s***...Just trying to explain some of the tuning "terms" to people browsing this thread, that may have no idea what we are talking about...
So Tonkabui, yes high load closed loop can self tune with pretty much any mods made as long as your required fuel mixture is never "richer" than what the wide band O2 sensor can recognize in the exhuast gas...Which pretty much will never be an issue with an FS...
I don't think any of the piggybacks out there fully support chaging the timing maps, however. For that, you would need a full standalone.
) but can be used as a piggyback by cutting the ignition and fuel wires and plugging into E6X. The Haltech F10 is fuel only.
