O2 Experiment 06 Xa Scion
 

Here is an update on my quest to understand how the O2 sensor operates and the possibilities for increasing fuel mileage.
I drive a stock 2006, Scion, Xa, automatic.
I ordered a manual from [URL="www.eagle-research.com"] E.F.I.E. (Electronic Fuel Injection Enhancer) and followed the instructions. They were accurate but careful attention is required.
The unit is installed and is adding 250~300 mV to the O2 sensor output.
I have just topped of the tank and will post a report in a week or two.

Briefly, the circuit I have installed adds to the voltage signal from the O2 sensor. (An Offset) This control loop uses the O2 sensor to continuously adjust the fuel injectors for the proper fuel/air ratio. This optimum fuel/air ratio is a calibration point of 500 mV. The added voltage changes the O2 sensor output to a value the computer (ECU) knows is rich. The ECU reduces the (on) time to the injectors until 500 mV is achieved. This new value is leaner because of the offset voltage. The automotive designers must use values that work for all drivers in all conditions. It is this area of (safety margin) that I believe some additional fuel savings may exist.

Is the 250-300 mV a fixed range or can you make adjustments to the offset?

Are you using your factory stock ECU?

I visited the site but had to search around to find the manual and unit. Found it here:
https://www.eagle-research.com/products/pfuels.html

Will be watching for your reports. Thanks.

Very interesting. What you say makes perfect sense, you can control the exact fuel AFR when the car is in closed loop by showing the ECU particular readings.

I'm assuming this is just wired inline with the O2 sensor and doesn't get adjusted much? So that a particular reading of 14.7 from the O2 sensor will now actually be 15 or 16:1 instead? This seems, just watch for any knocking. Reduced AFR means more chance for preignition. Most new cars ECUs will protect the engine by retarding the advance, but you'll lose power this way. You may find even with knocking (ie. retarded ignition timing and less power) that you'll still use less fuel and this may be perfect for you.

I'm not sure how you would calibrate it to be an exact AFR though (like 15.5:1 or whatever). I'd think an adjustable offset hooked to a wideband O2 sensor would be much more useful. You could ask an engine tuning shop if they'd tune your AFR for you, typcially dyno and engine tuning shops have their own wide band sensors they'll hook to your car for just the little while you're there and that'd definately be a cheaper option then buying a $200-300 wideband sensor.

I'm anxious for your results.

So this thing basically puts the car in a permanent closed loop? That actually sounds quite promising. I'll be interested to see the results of this.

EFIE Results from another user
 

Just to post some data points.

I've been using a eagle-research built unit since early 2003 and can report about 10% improvement in the Mazda (Ford) 2.3L dual plug motor. About 5% or less in a Nissan KA24E single plug. I can run much leaner with the dual plug motor as seen by using a cheap air/fuel ratio gauge. Still haven't measured added voltage by the EFIE.

This thing just steps up the voltage from the O2 sensor so the ECU thinks it's running richer and compensates by leaning it out. The changed O2 sensor signal still fluctuates as usual, and the engine runs like stock, just a little leaner.

itjstagame -

I have the same EFIE, but I haven't installed it yet because I wanted to finish my digital A/F ratio gauge (a kit you solder). With the gauge I am able to "see" what the EFIE is doing in real A/F ratio numbers, not just flashing lights. Right now I am breaking the A/F gauge in and I can see a dominant 14.7 ratio over time. Once I attach the EFIE, I will shoot for a 15.5 ratio and see what happens.

So many projects, so little time ...

CarloSW2

will this running lean destroy the factory cat? I've seen rich melt cats but not really sure on lean conditions.

ffvben -

In addition to worse emissions (more NOx), that's my worry also. That is why I am getting the A/F gauge online. It will put me in a position to "nudge" the EFIE into the lean without (hopefully) damaging the emissions system, or the engine. All of this scary stuff (i.e. You'll shoot your eye out!!!!) is less of an issue with GasSavers gentle driving style, but I am just repeating what I have read. I intend to have a switch to turn the EFIE on and off. From what I know, the EFIE is designed to have an on/off switch. That is to say, if it gets no power, it passes the unmodified voltage from the 02 sensor straight through to the ECU/PCM.

As a test, I attached the EFIE maybe a month or two ago but I didn't like their instructions. They basically said "lean it out until the car starts to stall" and then un-lean it back. In that scenario, I have no idea what the actual A/F ratio is.

But I don't think you need an A/F gauge to tune it. You only need a multimeter. Idle the car in your driveway with the multimeter patched into the 02 sensor. Whatever "dominant" voltage you observe is what the car considers to be 14.7. That will be the baseline setting for your EFIE.

This is the order that I think you have to obey when doing the test ...

Normal car :
engine -> exhaust 02 sensor -> car ECU/PCM

Monitor normal A/F ratio :
engine -> exhaust 02 sensor -> multimeter -> car ECU/PCM

Monitor how EFIE is effecting A/F ratio :
engine -> exhaust 02 sensor -> multimeter -> EFIE -> car ECU/PCM

The range is 0-1 volt for narrow-band and 0-5 volts for wideband 02 sensors.

CarloSW2

Running lean should not affect the cat in any way. Whereas running rich destroys it because of unburnt fuel increasing the temperature inside the cat running lean will mean less unburnt fuel and less of a chance to damage the cat. The increase in NOx emissions caused by this lean-burn will just mean the cat is less effective and is letting more slightly more pollution through. However, with how miserly us gassavers are with fuel, what is "more NOx emissions" to our cars is still less than "normal NOx emissions" for the leadfoot drivers of the world :D .

do you know this site: https://better-mileage.com/memberadx.html ?
It describe an alternative metod for change the o2 sensor signal.

I bought the electronics components, and the next month I will construct the device described at the Internet link

ciao

fabrio

in forecast to install the "o2 signal modifier", I installed news spark plugs: the ngk BKR5EXI-11 (iridium, with 0.8mm central electrode).

pregiate iridium electrode, not is the only difference between the original spark plugs, I bought the plugs with 1,1mm gap (the original gap it is only 0,8mm) this only just for to move up the misfire barrier.

My only thought is, which method in order to manage the device, that it should only work in particular RPM and load

Blue03Civic -

Woo hoo! Just what I wanted to read. That deserves a donut!

Attachment 797

I was wondering about the "GasSavers + NOx" equation too. It would be cool to be able to prove that as I approach "lean burn mode X", I still emit no more NOx than a normal driver with a stock version of my car, but still save more gas in the process.

CarloSW2

fabrio -

Yes, I have been to that site before. I am very sure that the better-mileage version is almost identical to the EFIE version. The EFIE that I purchased is dipped in insulating plastic, so I can't see the actual schematic. But everything I see in the better-mileage version looks like a close match to the EFIE.

The EFIE can be purchased already-built or as a schematic. Once you know the schematic, you can make your own. Heck, maybe the EFIE is based on the better-mileage version, :rolleyes: .

CarloSW2

Yep, check out my post about this from a couple of months back...

https://www.gassavers.org/showthread.php?t=3566

I am seeing a consistent 10% increase in fuel economy and a great deal of power loss running at 15.9:1.

Other than basic concept, I doubt it -- they use two totally different approaches.

The better-mileage version uses a variable-threshold Shmitt trigger scheme. In non-geek-speak, they're choosing what they want to call the middle of the sensor's range and sending the ECU a pulse train developed around that value. They use a LED dot/bar-graph driver IC to pick off different thresholds (unusual but clever), which means you get up to ten discrete adjustment settings.

The EFIE instead simply develops a constant (but adjustable) voltage and sums that to the signal already coming from the O2 sensor, almost as if you were to insert a battery in the signal line. Rather than discrete steps, it's infinitely adjustable.

I haven't studied either in depth, but at first glance both designs look like they'd get the job done just fine. Depending on the results you folks report, I may tinker with this in the future myself. :)

Rick

P.S. I read in some other threads that the wide-band (five wire?) sensors have a calibration resistor that tells the ECU how to interpret the reading; I wonder if on those you could just change the resistance to "remap" where it thinks 14.7:1 lives?

I understand how this thing works, but still have some questions about it... Does it have two 4 pin plugs coming off of it and a seperate power source line? Or is it just a mess of wires that you have to rig to the 02 sensor yourself and a seperate wire that runs to the power supply? Can you turn it on and off? Also, what kind of FE improvement are the users of it seeing in terms of highway FE?

Rick Rae -

Thanks for the correction.

And/or a potentiometer to fiddle with the resistance?

Here is another thing I was wondering. If an 02 sensor is comparing hot exhaust air to "ambient" outside air, couldn't we spoof the 02 sensor by modifying the surrounding outside air that the 02 sensor is sampling? And, would you want it to be cold air or hot air? I am wondering if grill blocks and other ways to keep the engine bay hot are having a secondary effect on the reading of the 02 sensor.

CarloSW2

OK, Zerfstead here.
It appears on my first tank and about 300 miles that the EFIE is working. I filled the tank on monday with 87octane and turned on the EFIE. Today is Thursday and I think the increase is about 14-15%. I notice a slight power loss during acceleration. It is working. The voltage offset is 260 mV. a conservative value. I am not ready to make a final acessment. My goal is to drive a maximum speed of 60 and run my AC as I normally would. This gives me about 35 mpg without EFIE on my usual drive to and from work (in city freeway). If I can ave 40-44 mpg on my drive to work I'm happy.

How many oxygen sensors do you have? My car for exemple have two of them, so this mean I'd have to connect EFIE device to each one.:confused:

holypaulie -

If your car is like mine, then you have one 02 sensor in the exhaust manifold and a second one that is pre (post?) cat. The only one that needs the EFIE is the one in the exhaust manifold, because that is the one the the ECU/PCM uses for closed loop operation.

CarloSW2

You have to connect the EFIE to all upstream o2 sensors. Don't worry about the downstream sensor that is after the cat.

edit: Well after looking at my factory service manual, my chevy would need both sensors tapped into EFIE...

Does running lean introduce the risk of burning a hole in your cylinder wall due to higher temperatures and free oxygen, or is that just a myth?

Yes, it does, but not at the "lean" we're talking about. I'm guessing we're seeing somewhere around 15-16:1 with the EFIE, which isn't really all that dangerous. If we were to lean out to say, 20:1 then I'd definitely suggest water injection to prevent said burning of cylinders.

cfg83 you have p.m. thanks in advance :thumbup:

Follow-up on my O2 EFIE install
 

Well I have been testing the EFIE on my Scion and have added a 5K resistor in parallel with the IAT sensor. this raised the IAT by about 8-10 deg F. A simple mod. I just pushed a T-pin through the two wires on the MAF wiring harness and inserted the resistor leads in the holes. A temporary installation to test for a ohm value I can live with.

So, with the EFIE set at 300 mv and the IAT at +10 F. here is how it looks.

Houston, TX Morning commute OAT 88 F for 38 miles.
All tires at max rated psi 45
Cruise ON for freeway
AC on
Speed for cruise = 60 mph
ave cruise mpg = 52
overall trip = 48.6
I forgot the ave speed number on the scangage I guess it around 38-40

These mods are conservative settings, yet are producing meaningful improvements in mpg.
Without these mods I could expect the freeway ave to be around 38-42.
I am reminded however... that the driving pattern, technique and other factors have a great deal to do with the final amount of gas consumed.
The greatest gains in fuel economy still come from me SLOWING DOWN and driving the speed limit.

Zerfstead you have a PM

Zerfstead -

There is the possibility that the IAT resistor mod is fooling the ScanGauge, at least for some drive-trains :

Batman we have lean burn! 49.6 mpg!
https://www.gassavers.org/showthread.php?t=2160

I agree with being conservative, better (engine) safe than sorry. I know the EFIE is working because I can see the AF ratio go lean and feel the engine lose power, but the ScanGuage may not be recording the effect :

Just ordered an EFIE - BrightGreen FeverBuster
https://www.gassavers.org/showpost.ph...87&postcount=5

My Theory : You're IAT resistor mod is not working, but the ScanGauge is reacting to it and improving your displayed MPG. You're EFIE is working, but the ScanGauge is not recording it's effect. Result? The ScanGauge is wrong but you are still getting better MPG.

This message has been brought to you by the Better Confusion Bureau, :o .

CarloSW2

overtime this is gonna cost you allot more then your saving in fuel.

bfg9000d
 

Hi sir. I for one would like to see documention concerning your listing. I'm anticipating some mods to my XB and would like to know if I'm slipping into deep water! Please advise, Ron. :confused: