o2 sensor mod - Fuel Economy, Hypermiling, EcoModding News and Forum

bandit86 · 03-29-2010, 11:29 PM

tried searching but I'll post this anyways.

did anyone modify their o2 sensor circuit to fool the car into running lean?

You can add a parallel high resistance divider cct, say 12Vfeeding 14kohm to 1kohm to ground. Inbetween the resistors there vill be 1 Volts with very little current availible (unless you hook it up backwards) and if this signal is tied into the o2 wire the ecu will see a richer condition and go about leaning it out. if you hook up a microswitch to the pedal, it'll automatically go back to normal at more then light throttle.

Other thing I got on my mind, how about running smaller fuel injectors at higher pressure? The end result should be better atomization of the fuel

discovery · 03-30-2010, 07:11 PM

Good idea for the O2 sensor.

About the injectors then you need to change the fuel pump as well.

bandit86 · 03-30-2010, 11:35 PM

Quote:

Originally Posted by discovery

Good idea for the O2 sensor.

About the injectors then you need to change the fuel pump as well.

no you wouldn't , need to find a way to adjust the pressure regulator.

wagonman76 · 03-31-2010, 01:10 PM

Quote:

Originally Posted by bandit86

no you wouldn't , need to find a way to adjust the pressure regulator.

Depends on the car. On my vehicles, it is designed to regulate to about 90% of the pump pressure. Not much reserve left. It seems like most cars would be like that, I mean why would the manufacturer put in a lot more pump than is needed and increase cost?

I built an adjustable circuit once to trick the O2 sensor into leaning the mix. It leaned it out all right, but when leaning it out it also killed FE.

Other cars may vary.

Daox · 03-31-2010, 01:19 PM

Its not the best idea with narrow band O2 sensors. They just don't have the resolution to run anything but stochiometric air fuel ratios. You could hack the sensor, but your a/f ratios would likely be all over the place and you wouldn't even know it.

cfg83 · 03-31-2010, 01:39 PM

bandit86 -

I have one for my narrow-band 02 sensor but I disabled it :

http://ecomodder.com/forum/showthrea...efie-1308.html

I wasn't comfortable with the idea that I was hurting my emissions. If you read the thread, you will see that it appeared to be working in a funny way. However, I never used it enough to ascertain if it was helping MPG.

CarloSW2

tangomar · 03-31-2010, 02:18 PM

Carlos is right.

You probably have multiple O2 sensor and you have to fool them in the same way. This means that you might need 4 EFIEs. At that point you might need to adjust MAP/MAF, TPS, IAT, ... as well.

Isn't cheaper to remap your ECU at that point? You can have it tuned perfectly as you wish.

Another way to do it is to use a Volo Performance chip. They are quite cheap right now: FS1 Fuel Saver
They soft patch the ECU continuously. Some people reported good savings on another forum.

I would still monitor the exhaust temperature to make sure you aren't going to burn anything.

2win2rbo · 04-05-2010, 09:13 AM

Quote:

Originally Posted by bandit86

tried searching but I'll post this anyways.

did anyone modify their o2 sensor circuit to fool the car into running lean?

You can add a parallel high resistance divider cct, say 12Vfeeding 14kohm to 1kohm to ground. Inbetween the resistors there vill be 1 Volts with very little current availible (unless you hook it up backwards) and if this signal is tied into the o2 wire the ecu will see a richer condition and go about leaning it out. if you hook up a microswitch to the pedal, it'll automatically go back to normal at more then light throttle.

Other thing I got on my mind, how about running smaller fuel injectors at higher pressure? The end result should be better atomization of the fuel

Hmmmm.... Sounds like a good thing to try.

eco86 · 04-12-2010, 08:09 PM

I don't know about modding the O2 sensor, like Daox said, narrowband sensors are really only set to work at stochiometric ratios. However, I have modified the Exhaust Gas Recirculation (EGR) valve on my Accord with good results. The Accord uses a resistance value to figure out how far the EGR valve is open, so by connecting a potentiometer to the valve's lift sensor circuit, I can dial in more resistance to open the valve more or less. I added a switch to toggle in and out of the modified circuit, but so far I haven't had to switch it off.
The modified EGR circuit seems to be giving me a 10-15% bump in fuel economy, mostly at moderate throttle openings, but I still need to formally test it.
Autospeed has a writeup of their own test (which inspired me to try it) where they modified the EGR on a first generation Honda Insight, and they ended up with a solid 10% improvement, mostly in city driving.