Lambda reads as the amount of air in relation to fuel. So 12:1 on E85 is the same as 12:1 on gas.
Tune the same way you have been with gas, dynoing the car might reveal that E85 likes it a touch fatter but your car will tell you on the dyno if that works or not.
Hi folks, my first post here but thought I would comment on this thread. For background I am the guy on the Subaru board NASIOC that did the E85 FAQ over there.
A wideband O2 as mentioned above only measures the lambda reading which is independent of the fuel you are burning. Lambda 1.0 is stoichiometric mixture on any fuel. Most widebands assume you are running gasoline and compute the AFR based on that assumption. For example a lambda 0.82 on gasoline is 0.82 x 14.7 = AFR 12.054. The true stochiometric mixture for E85 is about 9.7:1 AFR but on a gasoline calibrated wideband it will show up just like gasoline as an AFR of 14.7:1.
In practice people generally do one of two things. They get comfortable using lambda numbers only or they stick with the gasoline AFR's just because they are used to working with them. You will generally find E85 likes to run just a tad richer than best power AFR's you found on racing gasoline, until you get into the higher boost ranges than you will have to add even more fuel. (E85 has wider flammability limits than gasoline so will run as much as 40% rich of stoichiometric mixtures where gasoline generally will not go much beyond 25% rich of stoichiometric for best power)
In the turbo import cars, we tend to get best power at lambda 0.72 - 0.76 on most cars. That would be a gasoline calibrated AFR of 10.584 - 11.172. When I first converted my WRX to E85 it was a simple conversion where I just increased the fuel injector size by 30% and it was quite happy running at a gasoline calibrated AFR or 11.5 at wide open throttle.
Due to E85's high octane and high evaporative cooling you can run much leaner than max power mixtures at lower load, if your engine management system allows you to tune the full range of load values. On my car I run lambda 1 all the way up to about 5 psi boost at light throttle low load conditions (highway cruise just tipping into the throttle lightly to over take another car). At higher loads I have the car set up to run a mixture of lambda 0.76-0.78 (which gives me slightly better fuel economy). I only run richer than that if I am cranking up the boost above 14 psi, but I generally drive around town with the boost turned down.
Glad to see you guys are getting into E85 I think you will find it a very forgiving fuel and lots of fun if you want to go balls to the wall on your tune.
Larry
The simple fact is that a WB O2 sensor reports what it sees. And what it sees varies according to the fuel used.
This is why when running alcohol you will find that a richer then expected lambda makes the best power.
The lambda reading of a wide band is completely fuel independent. It is simply a measure of the free oxygen concentration in the combustion gases. The sensor neither knows or cares what you are burning all it is measureing is the unburned oxygen concentration. Larry
And what free oxygen is there is a fuel rich exhaust? None.
The issue as I see it is that you do not understand what a wide band O2 sensor is responding to.
then why do the 'real' WB systems ($5,000 to $8,000 cost units) have setable C & H ratios on the front panel?
Bosch Automotive Handbook 6th Edition Pg 133-134
"Oxygen-concentration sensor (lambda oxygen sensor)
The fuel-metering system employs the exhaust-gas residual-oxygen content as measured by the lambda oxygen sensor to very precisely regulate the air/fuel mixture for combustion to the value (lambda)=1 (stoichiometric combustion P. 605)
The sensor is a solid-state electrolyte made of ZrO ceramic material. At high temperatures this electrolyte becomes conductive and generates a characteristic galvanic charge a the sensor connections;this voltage is an index of the gas oxygen content The Maximum variation occurs at lambda=1.
Electrically heated sensors are especially well-suited for measurements in the lean range, and already come into operation in the warm up phase.
For the wide band range, flat and smaller "wafer sensors of multilayer ceramic design (broadband lambda oxygen sensors) are used; these sensors can also be used in diesel engines. A sensor of this type is essentially a combination of a conventional concentration sensor which acts as a galvanic cell (Nernst sensor) and a limit current or "pump cell". A voltage is applied from an external source to the pump cell, which is the same design as the conventional concentration cell. If the voltage is high enough, a "limit current" sets in which is proportional to the difference in oxygen concentration at both ends of the sensor. Oxygen atoms are transported - depending on polarity - with the current. An electronic control loop causes the pump cell to supply the concentration sensor permanently through a very narrow diffusion gap with precisely enough oxygen from the exhaust gas to maintain a status of lambda=1 at the sensor. In other words, oxygen is pumped away in the event of excess air in the exhaust gas (lean range); in the event of a low residual-oxygen content in the exhaust gas (rich range), oxygen is pumped in by reversing the pump voltage. The relevant pump current forms the output signal.
Did you calibrate the sensor in free air before you did your runs?when I played back those runs it was so far off of the lean scale I did not know what to do
Just the calibration task as mentioned above on mine.when I played back those runs it was so far off of the lean scale I did not know what to do
The wide band sensor is basically a chemical battery that measures the partial pressure of O2 in the exhaust gas. In the case of rich mixtures it measures the amount of oxygen it must pump through the sensor cell to reach the stoichiometric reading.
Because unlike affordable widebands, they do not assume what fuel you are using and must know the C & H ratio to compute the true AFR from the indicated lambda reading.
The Innovate site has lots of good technical info on the WBO2 sensors including information directly from Bosch.
Since Bosch developed the O2 sensor, they are the "source" for information.
Larry
WRX, I have recalibrated this thing a couple of times and comes to 20.9%, install it took her out for a couple of runs at 18-19lbs boost vs. the 25lbs I was running earlier and the same thing off the scale on the lean side, if you like I can send you the first 7 sessions as I have them on this computer
here at work, the other 2 runs are on my laptop in my car and they were at18-19lbs vs the 25 lbs on the first 7 runs, they look scary, but maybe there is a misfire, if so I do not feel it what so ever, car runs out strong, let me know. Maybe I will install my other plugs which have just a few hundred miles on them and see what happens, Just love changin plugs in these cars, I think
I an do it in my sleep, lol
Ron