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What is Data?
Data is defined as a collection of facts from which conclusions may be drawn. When speaking of engines, a tuning decision (e.g. should I jet up or down?) must be based on a variety of good data (such as the air-fuel ratio is 14:1 at 5000 rpm). While weekend enthusiasts and amateur racers realize the importance of having good data to tune with, the problem has been in obtaining this data. We all have gauges in our car to keep us apprised of vital stats, but they only give us a single-point of data in real time. There is no easy way to consolidate all the data, or go back and look at what transpired. As a result most of us spend our time tuning on a chassis dyno or at the track, where there is an end result -a number, to work with. While this type of tuning has merits, the information gained from it is limited and many times circumstantial. For instance, if we come into the dyno shop making 300 horsepower, and leave making 320, we may erroneously conclude the engine is now properly tuned. While many dynamometers have the ability to monitor air-fuel ratio and rpm, you are still leaving out many other important and vital engine tuning parameters, such as fuel pressure, exhaust gas temperature, and boost pressure to name a few. This is aside from the issue of not tuning under actual road and load conditions.

Data Logging for Everyone
Take a glance in the pits of almost every professional auto racing series and you'll witness just as many laptops as tool boxes. The type of data logging system in use by professional teams can record as many as 100 different parameters on the race car and send it all back to the pit crew via telemetry. Such systems cost tens of thousands of dollars and were never intended for the recreational consumer. However, the concepts and technology are certainly very applicable, and it was just a matter of time until companies marketed streamlined, and more affordable, data logging systems.


Wide-band O2 sensor eliminates the need to visit a dyno just for A/F data.
We recently tried out one such system developed by Innovate Motorsports. The LM-1 digital data logger incorporates a wide-band oxygen sensor plus five additional channels in order to make for some very powerful tuning capability. In its most basic form the LM-1 unit, which ships with the Bosch LSU 4.2 wide-band O2 sensor and a 10 ft. cable, can record and display air-fuel ratio from the exhaust stream. The unit samples at a rate of 12 times per second and will store up to 44 minutes of data. You do not need a laptop in the car to record and you can record multiple sessions. This means you can go out for a tuning session and separately record each wide open throttle blast you make. You then use the supplied cable to download the data to your PC and analyze the results with the LogWorks software.

While the wide-band O2 sensor is in itself a huge tuning tool, the real power of the LM-1 is in its ability to log five other channels. Think of a channel as a port though which data can be captured. Data comes from sensors, and for the LM-1 the sensors must generate an output signal between 0-5V. If this sounds confusing don't worry, we'll get into that later in this article. Using sensors enables you to view A/F ratio in the context of other parameters, such as rpm, boost pressure, throttle position, injector pulse, fuel pressure, or whatever else you can think of.

In order to populate the five channels in the LM-1 unit you need one of the two available auxiliary units (see side bar.)
With either of these devices one can populate rpm using a tach-lead and also the remaining channels using common automotive 0-5V sensors. For instance, if you wanted to view fuel pressure you could use a pressure transducer, such as those in Autometer fuel pressure gauges, which send a linear 0-5V signal corresponding to rise in fuel pressure. Most sensors on late-model "computer controlled" vehicles, such as throttle position and MAP sensors, output a 0-5V signal. They can be easily adapted onto early vehicles for purposes of data logging.

Capturing the Data
Over the past month we've been using the LM-1 to tune and troubleshoot our supercharged Project '67 Mustang (see "High on Carbs") as well as our '01 GT which recently received a nitrous kit (see "Bottle Feeding"). Project '67 is a great example of how dyno tuning can paint an incomplete picture of where an engine really stands. The supercharged 331-cid motor produced over 500 horsepower to the wheels on a dyno. While the numbers were impressive we were experiencing different results on the dyno than on the road. On the dyno we would see boost hit 8 psi, while on the road we were only seeing 4-5psi. Rather than continue to tune the car on the dyno we used the LM-1 to obtain actual road conditions for rpm, boost pressure, fuel pressure, and air/fuel ratio. More


(Capturing and Analyzing Data)
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In This Article:
We explore the power of data logging using Innovate Motorsports LM-1 digital wide band oxygen sensor and data logging device.
 


The LM-1 Digital Air/Fuel ratio meter. The base unit is includes a Bosch LSU 4.2 wide-band oxygen sensor and software for viewing/replaying the data. The unit has the ability to capture five additional channels of data, using an auxiliary input devices below. At about $350 the base unit pays for itself in a few hours of dyno time.

 

The LMA-3 or "Aux Box" is a necessary add-on device for the LM-1 if you want to take advantage of the data logging capabilities. The unit comes with built in sensors for MAP (manifold absolute pressure), RPM converter, thermocouples (for exhaust gas or cylinder head temperature), as well as an accelerometer and duty cycle sensor. There are also five external inputs for connecting your own 0-5V sensors. This unit is $250. A streamlined version, the LMA-2, is only $99 and has a built in RPM sensor.
 
O2 Sensors - Wide vs. Narrow
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, such as the Bosch LSU 4.2, utilize a more sophisticated sensing element which enable it to produce precise voltage output in proportion to the air/fuel ratio (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 reduced prices to as low at $50.
 
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