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air/fuel ratio question??
Posted: Sun Nov 25, 2007 4:41 pm
by SuBaRiNo
Just confirming something... according to the instruction booklet on a Air/Fuel gauge i just got... normal operation is...
Heavy Deceleration = Lean
Heavy Acceleration = Rich
And everything inbetween should be normal air/fuel ratio.
Does this sound right?
Dave
Posted: Sun Nov 25, 2007 5:27 pm
by littlewhiteute
Dave,
Maybe if I ask the manufacturer and how much the gauge cost?
If it's a narrow band gauge, (power, ground and O2 signal) then what you have said is correct.
The gauge will read max lean on decel above 2000 rpm due to fuel cut on decel.
The gauge will probably read rich (or should do) under load.
It will cycle around 14.7:1 (stoichiometric) at cruising speeds.
Personally, once you have used a TRUELY accurate wide band o2 gauge, narrow bands are a waste of time.
I certainly would not trust one to tune by.
Posted: Sun Nov 25, 2007 7:13 pm
by SuBaRiNo
Excelent. Yeah narrow band... it's more to give me an indication than anything else. Thanks for that.
Dave
Posted: Sun Nov 25, 2007 9:12 pm
by Gannon
I just bought one tonight, ebay jobbie.
Im gettin it for the same reason, just as an indication so i can see when something is going wrong.
Posted: Mon Nov 26, 2007 11:53 pm
by subanator
Sorry as I understand it a narrow band is only good for cruising to achieve a perfect stoichiometric 14.7:1, so under boost you dont want to lean out on a turbo lower than 13.5.
A wide band sensor (4 wire) is what you want for monitoring really as it will cover a bigger range. J-car kits can be made up to take these and have an on dash meter. The better ECU's run 4 wire sensors. But as mentioned before elsewhere a MAP AFM come included with some aftermarket ECU's, and will give a bigger range of control and adjustment to A/F ratio. (Dave, things get real complicated from here on in when boosting a stocker, hang in for the ride, it will be worth it!)
Posted: Tue Nov 27, 2007 9:31 am
by discopotato03
Do a search on Tech Edge (in Canbera I think) .
There is a lot of misinformation on "wideband" oxygen sensors , in recent times fast accurate 02 probbes are much cheaper than they used to be and that was the real breakthrough . The real ones are the pump cell type which you can read about at Tech Edges site and many others .
The much talked about Bosch 4 wire probe actually runs a wide band emulation so its neither as fast or as accutate as the pump cell types - and very expensive too boot .
Another term you'll see if youve had anything to do with Haltech is "UEGO" pronoumced you ae go . All it means is universal exhaust gas oxygen sensor .
Food for thought cheers A .