Wideband Differences

[rustyknuckles]

im looking for a wideband and since there is no "perfomance" section, i got an srt-4... so i'll post it here..

to keep from any "plagarism" issues...this info was found on:
http://www.fordmuscle.com/archives/2007/06/WidebandShootout/index.php
and
http://www.musclemustangfastfords.com/tech/mmfp_0707_mustang_wideband_data_logging/index.html

Background
The art of tuning an engine is not new, dating back to the birth of the internal combustion engine over 100 years ago. For a generation or two, methods such as vacuum gauges, CO meters, and the black art of reading spark plugs were the main tools in a tuners arsenal. Due to the lack of accuracy of these methods, tuning was nothing more than subjective analysis and best left to the seasoned professional.

Later, as emissions standards tightened and as racing engines started to produce higher and higher outputs, the need to accurately determine air-fuel ratio became increasingly important. Technology improved and wide band air fuel ratio meters with embedded data logging equipment emerged. For many years this technology was out of reach for all but the most well heeled DIY tuner. The cost of accurate reference level wideband air fuel ratio meters was in the several thousand dollar range.

The affordable meters on the market, at the time, used conventional narrow band O2 sensors- the same type of sensors found in most early EFI cars. Such sensors are only accurate around the stoichiometric range, which is an air fuel ratio of 14.7:1. Accuracy in this range is useless for performance tuning where wide-open throttle ratios may drop as low as 11:1, and certainly in the 13:1 range for most naturally-aspirated engines.

The big breakthrough for the performance aftermarket occurred when Bosch made the LSU4 wide band O2 sensor available for a reasonable price, and the aftermarket responded by making affordable wide band air fuel ratio meters using this sensor. This is a boon to the DIY tuner as now there are many wideband air fuel ratio meters available on the market for a reasonable price.
i dont have a password nor the $7 to get to page 2... so if you have a password, feel free to paste...

What is a Wideband sensor?
Standard "narrow band" O2 sensors operate between 0 and 1 volts, and are only capable of accurately measuring a stoichiometric air/fuel ratio (e.g. 14.7:1). A richer or leaner condition results in an abrupt voltage change (see Fig 1.) and thus is only useful for qualitative determination. Modern automobiles use this "switch" like sensing at idle and part throttle to make small compensations in fuel delivery to keep the air/fuel ratio near 14.7:1.

Wide band oxygen sensors utilize a more sophisticated sensing element which enable it to produce precise voltage output in proportion to the oxygen in the exhaust (see Fig 2.) As a result a wide band sensor can measure accurately from as rich as 9.0:1 to as lean as free air. Wide band sensors used to be cost prohibitive, however recently their wide spread use has resulted in lower prices.

Not All are Equal
Many questions have arisen since the widespread availability of wideband air-fuel meters.

First, since all of these meters use the same Bosch sensor, and since this sensor is factory calibrated, are they all more or less equal? The answer is no. There is significant difference between the controllers and circuitry used in the various meters. How the sensor's heater is controlled and how the pump current is switched and controlled, for instance, are critical for accurate sensor operation. Other questions also can be posed: Which meter is the best performing one? Which meters have the features I need?

With these question and few subjective answers to be found, we set out to determine which meters were the best. The task was a difficult one but we were determined to find the answers.


Methodology
The plan was to take eight popular units and test them right out of the box using calibrated compressed gas. We'd then run them for an hour on a test engine, with leaded race fuel, to simulate wear on the sensor. Finally we'd test them again with calibrated lab gas. The compressed gas is from Scott Specialty Gasses and formulated to SAE standards for .8 lambda and .895 lambda (11.76 AFR and 13.15 AFR respectively). The gas gives us a control with which we can test each sensor without introducing variability - such as a change in rpm if we were to use the test engine's exhaust gas. To further control the study we used Westech's expensive ECM LambdaPro which read dead-on for both of the gas controls.

During the dyno testing, we also logged data from all of the units. This gave us a chance to configure each unit's analog outputs, and to compare response time (latency) and accuracy under various loads, sweeps, and conditions. We also verified that the logged data matched the values displayed on the various gauges and displays. All the units shared a common and robust power and ground setup.

The chart on the following page summarizes our findings across four categories. Of particular note was the issue of re-calibration. All of the units certainly rely on the factory calibration of the sensor from Bosch. The manufacturers may even perform some sort of a calibration of the sensor to their units during their assembly process. However, as far as we could tell, only two units appeared to be capable of re-calibration to compensate for sensor wear. The Innovate unit is self calibrating, while the NGK requires the user to turn a knob until the display reads "CAL." Both measure the air-fuel ratio of free air to calibrate the sensor.

This raised the obvious question: If a unit is not capable of calibration, how does the user know when the sensor is going bad? We know from the Bosch data that the sensors themselves change as they age.


How the test was done

i think the picture speaks for itself...:good:

and the results...

 

[rustyknuckles]

part 2

info on why a wideband can benefit you....

from the innovative motorsports site....

You CAN be too Rich

By Klaus Allmendinger, VP of Engineering, Innovate Motorsports

Many people with turbochargers believe that they need to run at very rich mixtures. The theory is that the excess fuel cools the intake charge and therefore reduces the probability of knock. It does work in reducing knock, but not because of charge cooling. The following little article shows why.

First let’s look at the science. Specific heat is the amount of energy required to raise 1 kg of material by one degree K (Kelvin, same as Celsius but with 0 point at absolute zero). Different materials have different specific heats. The energy is measured in kJ or kilojoules:

Air ~ 1 kJ/( kg * deg K)
Gasoline 2.02 kJ/( kg * deg K)
Water 4.18 kJ/( kg * deg K)
Ethanol 2.43 kJ/( kg * deg K)
Methanol 2.51 kJ/( kg * deg K)

Fuel and other liquids also have what's called latent heat. This is the heat energy required to vaporize 1 kg of the liquid. The fuel in an internal combustion engine has to be vaporized and mixed thoroughly with the incoming air to produce power. Liquid gasoline does not burn. The energy to vaporize the fuel comes partially from the incoming air, cooling it. The latent heat energy required is actually much larger than the specific heat. That the energy comes from the incoming air can be easily seen on older carbureted cars, where frost can actually form on the intake manifold from the cooling of the charge.

The latent heat values of different liquids are shown here:

Gasoline 350 kJ/kg
Water 2256 kJ/kg
Ethanol 904 kJ/kg
Methanol 1109 kJ/kg

Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13. Let's assume the optimum is in the middle at 12.5. This means that for every kg of air, 0.08 kg of fuel is mixed in and vaporized. The vaporization of the fuel extracts 28 kJ of energy from the air charge. If the mixture has an air-fuel-ratio of 11 instead, the vaporization extracts 31.8 kJ instead. A difference of 3.8 kJ. Because air has a specific heat of about 1 kJ/kg*deg K, the air charge is only 3.8 C (or K) degrees cooler for the rich mixture compared to the optimum power mixture. This small difference has very little effect on knock or power output.

If instead of the richer mixture about 10% (by mass) of water would be injected in the intake charge (0.008 kg Water/kg air), the high latent heat of the water would cool the charge by 18 degrees, about 4 times the cooling effect of the richer mixture. The added fuel for the rich mixture can't burn because there is just not enough oxygen available. So it does not matter if fuel or water is added.

So where does the knock suppression of richer mixtures come from?

If the mixture gets ignited by the spark, a flame front spreads out from the spark plug. This burning mixture increases the pressure and temperature in the cylinder. At some time in the process the pressures and temperatures peak. The speed of the flame front is dependent on mixture density and AFR. A richer or leaner AFR than about 12-13 AFR burns slower. A denser mixture burns faster.

So with a turbo under boost the mixture density raises and results in a faster burning mixture. The closer the peak pressure is to TDC, the higher that peak pressure is, resulting in a high knock probability. Also there is less leverage on the crankshaft for the pressure to produce torque, and, therefore, less power.

Richening up the mixture results in a slower burn, moving the pressure peak later where there is more leverage, hence more torque. Also the pressure peak is lower at a later crank angle and the knock probability is reduced. The same effect can be achieved with an optimum power mixture and more ignition retard.

Optimum mix with “later” ignition can produce more power because more energy is released from the combustion of gasoline. Here’s why: When hydrocarbons like gasoline combust, the burn process actually happens in multiple stages. First the gasoline molecules are broken up into hydrogen and carbon. The hydrogen combines with oxygen from the air to form H2O (water) and the carbon molecules form CO. This process happens very fast at the front edge of the flame front. The second stage converts CO to CO2. This process is relatively slow and requires water molecules (from the first stage) for completion. If there is no more oxygen available (most of it consumed in the first stage), the second stage can't happen. But about 2/3 of the energy released from the burning of the carbon is released in the second stage. Therefore a richer mixture releases less energy, lowering peak pressures and temperatures, and produces less power. A secondary side effect is of course also a lowering of knock probability. It's like closing the throttle a little. A typical engine does not knock when running on part throttle because less energy and therefore lower pressures and temperatures are in the cylinder.

This is why running overly-rich mixtures can not only increase fuel consumption, but also cost power.

 

[Dysphagia]

thats why i'm rollin the lm-1

 

[Cygnus]

Awesome information!!!!

I'm glad I went with the Uego!

 

[rustyknuckles]

i have my eyes on a used wideband from a local guy... but the wifey said i spent too much money for x-mas... BUT most of it was for her!

i dont get it!?!

 

[Cygnus]

Agree.... it should be a sticky. Very useful information!

 

[Enforcer 3]

Very good info. Glad I have the LC-1 with XD 1.

 

[Quick]

nice to see my innovate LM-1 ranks high on the list. Also, enjoyed the infomarmational part. I think this should be a sticky. Milan, not that kind!

The innovates are a top of the line gauge but the Ford Muscle test was less than scientific.

 

[turbosocks]

dang, i had the plx m-300 in my turbo tib.. i bought it because i thought it was one of the better widebands. turns out to be garbage. and i thought i was running a WOT full boost AFR of 11.82:1 when i coulda been running almost a 13:1 AFR at full boost.. : ( not good.

 

[Quick]

dang, i had the plx m-300 in my turbo tib.. i bought it because i thought it was one of the better widebands. turns out to be garbage. and i thought i was running a WOT full boost AFR of 11.82:1 when i coulda been running almost a 13:1 AFR at full boost.. : ( not good.

I don't know about the PLX m-300, but why do you think this?

 

[turbosocks]

according to the test results, the m-300 got a poor in accuracy which means that the AFRs accuracy was +-1.00

 

[Quick]

I wouldn't put much stock in that test. Supposedly it was not very scientific and they have not responded to say otherwise. There is also a glaring lack of raw data and testing methodology being made available. I don't know if the m-300 is good or bad but I wouldn't draw any conclusions from theirs as it stands.