alright, i asked ninesecrx this question and he didnt come up with a difinitive answer. i posted in this forum because alot of serious racers browse this place. anyways, i know the A/F guages dont work too well. but if u hook them up INDEPENDENTLY of the ECU will they b more accurate??? the reason i ask is because my uncle has a stand alone system on his rock crawling jeep. when i watched his A/F guage it was rock steady (not bouncin back and forth) except when he first floors it, then it went to lean. but throughout my ride in his jeep (yes it is EFI too) it was just movin a slight amount. so back to the original question, if u hook up the A/F guage independently will it work accurately???

 

I would think if it was hooked up to a Wideband, it would be more effective...

Isn't the inherant problem with them the limited voltage range of the stock O2 Sensor?

Suprdave

 

No, it won't matter. What you're decribing is a different issue of how the EFI system works, and doesn't have anything to do with "sharing" the O2 signal.

 

The gauge bouncing around is a result of the way the Honda ECM operates. It switches constantly between lean and rich to determine a proper a/f ratio for cruising, idling and fuel economy. Most stanadlone systems have closed loop as an option, most don't use it. I'm assuming your uncle's Jeep doesn't since the O2 never moves from the target a/f ratio on the gauge. 0-1v O2s are inaccurate period. Most people down the Autometer gauge as being inacurrate, but they have no proof for that. The Autometer is only as inaccurate as the limited range o2 sensor that drives it. Also, a lot of users don't understand that the O2 is meant to bounce around and that is a function of the ECM as described above. Damn, theres my rant, tired of typing, sorry.
Jared

 

i know the bouncin is a result of the ECU plotting different fuel ratios. my uncles jeep runs the autometer guage with a 3 wire O2 i believe. heat, signal, and ground.

 

yep. if your running an a/f guage of an o2 and the movement is slow, usually mean the o2 sensor is on the way to the garbage can. the guage should sweep rapidly.

o2 sensors usually send a voltage ever half seccond. independent of the ecu. the ecu knows what the intervals between readings should be under certain circumstances. if these intervals to not match up for a set period of time the ecu will thwo a code. also if the o2 sensor is shot and displays a lower voltage what what the ecu expects over a period of time it will also throw a code.

i run a voltmeter up to thousanths of a volt of an independent o2 sensor. and tune off that. works great. this method has been reported as being dead on accurate with wide band o2 sensors. id still trust a wideband more tho. however nothing has detonated to date

edit: http://www.6speed.org/wideband.php link on making your own wideband o2 sensor. saves aprox 800$ no clue on how well this works tho


[Modified by TorteX, 12:02 AM 11/29/2002]

 

The sensor is not an active component, and puts out a <U>constant</U> voltage representing the air/fuel ratio. If the supply voltage is being pulsed then yes, the output will pulse.

 

blah lemmie rephrease turkey got to me aparently

there ya go

 

BTW, thanks for the link. I love projects like this, no hard thinking involved, just put it together