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Wideband o2 sensor?


Mk1Daniel

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I prefer some different numbers, i like high 15's low 16's in the cruise at very low load and low 12's at full load. ( turbocharged applications)

Idle number is pretty well irrelevant, I have seen a big variation on what idles well on relatively similar engines.

Horses for courses though I guess..

You probably need a bit more engine info for us to really assist.

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My crossflow with a bcf2 liked 12.6 at wot and 15.5 at cruise, 36 degrees of timing at wot too.

Where did you get your numbers from Roman, 14.7 is too rich and 13 is too lean imo. Not to mention that stoic is the hottest burn, so you are heating things up unnecessarily for no reason.

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Suppose it's not too far OT.

Specific heat is the amount of heat energy require to raise the temperature of a mass by 1C.

I was just kind of trying to illustrate, in a round about way, that it's not the temperature so much as the amount of heat energy being created. If it was just down to temperature then everything would melt as soon as the sparkplug went off :)

At cruise you're not creating large amounts of heat energy because you don't need to, as you are cruising.
If you went WOT at the same AFR then you're creating a lot of heat energy @ a high temp (which means it transfers into the mass faster due to temp gradient) beyond the ability of the coolant system to transfer the heat away.
So both power (see above graphs) and temperature is why AFRs get lower under increased load.
 

A car may like 14.7 at cruise due to gearing/spark/head design/octane/induction/air density/million things more than a leaner burn.
Probably not so much modern engines with their targeted afr design parameters and their precious metal mine in the exhaust :)

 

I'm pretty sure you know all this and it was just my obscure way of putting things :P

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I've seen a few posts about wiring/programming the ecu so the sensor is only on when the engine is running.

How would you achieve this on a carbureted oldschool donk? Put it on a switch and be very disciplined?

Does it hurt it to not be on at all if the engine is running/driving?

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I've seen a few posts about wiring/programming the ecu so the sensor is only on when the engine is running.

How would you achieve this on a carbureted oldschool donk? Put it on a switch and be very disciplined?

Does it hurt it to not be on at all if the engine is running/driving?

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Does it hurt it to not be on at all if the engine is running/driving?

 

Yes you need to have it running while the motor is running or they crap out.

 

When they're up to temp they burn off contaminants, I think they end up getting clogged if you dont.

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you could make a pretty simple latching circuit that would turn on when you crank the car, and off when you go to off position? should be pretty safe that way? and maybe put an LED in the dash to warn you its on for those odd times maybe?

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ok, so try this.

RS3EQy.jpg

So you probably dont need the capacitor, and you can get relays with built in protection diodes or resistors which will be fine, so you wont need the diode either.

The LED is only if you want it. Resistor wise, a 1K to 3.3K will be fine. 680R to 10K will work but gets a little dicey. Bigger the value, the dimmer the LED.

Its a double pole double throw relay (DPDT), but you could use 2 singles as well and wire them in parallel.

you COULD use a single relay, and wire the wideband output from the same line that feeds the relay coil, but its nicer to have a separate relay for that stuff... as i dont know how much current you can draw from the ON signal.

The idea is that the start signal powers the coil of the relay, which then flicks over and starts running off the 'on' signal from the key. It will stay that way until you turn the motor off by switching the key to ACC or Off. This means you should still be able to switch off the motor and leave it on ACC and listen to the radio without burning out your 02 sensor.

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