by FordMuscle Staff

Bog, flat spot, hesitation, stumble, and surge. These vague descriptors are examples of the challenges faced when tuning your own carburetor. Something has always seemed odd about deriving very quantitative decisions, such as choosing a 80 jet over a 76 jet or one metering rod size over another, from such ambiguous terminology. And what the heck is the difference between a stumble and a bog anyway? Before you email FordMuscle the answer, be aware that we no longer need clarification. Why? Because we are the latest disciples of the purely quantitative and completely logical tuning method that is known as the wideband tuning system.

Wideband refers to the use of a wideband oxygen sensor. Wideband O2 sensors are nothing new and if you've had your car on a chassis dyno that measured air-fuel ratio, it was likely using a wideband O2 sensor mounted in your tailpipe. However, what is new is the 'tuning system' in the hands of the everyday enthusiast. Gone are the days of having to pay handsomely for dyno tuning time just to get air-fuel ratios. With Innovate Motorsports' LM1 Digital Wideband kit and RPM Converter you can tune on your clock, under real road conditions, for under what it would cost for three or four dyno sessions. The system combines two very powerful tuning "inputs"; air-fuel ratio and rpm. By measuring and logging these two variables, you have the ability to tune absolutely anything for optimum power, fuel economy, or the best of both. We'll show you how.

About the Innovate Motorsports Wideband Tuning System
The Innovate Motorsports LM-1 kit with RPM Converter is a complete wideband tuning system. The single self-contained unit combines a wideband air/fuel ratio sensor controller, a 6-channel data logger, and an easy-to-read backlit LCD display. This RPM Converter converts a normal tach signal to an analog RPM signal that can be logged by the LM-1. The system includes LogWorks software for powerful results analysis and real-time data viewing.

Carburetor Tuning with the Wideband Tuning System
Whether you consider yourself a beginner, an amateur, or a professional at tuning carburetors the old-fashioned way, don't be afraid to adopt the digital tuning technology found in the LM-1. The satisfaction of making carburetor tuning decisions based on quantifiable data logged by this wideband air/fuel meter is not difficult to realize. We demonstrate on FordMuscle's Project MX.

Setting up the Innovate LM1 begins with installing the supplied oxygen sensor fitting into your exhaust stream. Any exhaust shop can weld this fitting in for you, just be sure it is in a location where the installed sensor will not hit the ground or interfere with the chassis. The fitting is best placed in the header collector or just after it, on either side. Place one in each side if you want to tune each bank individually.
The unit has a 9V battery to power up for data transfer purposes, however you need to supply it with 12V power to preheat the Bosch wideband oxygen sensor. The kit comes with a cigarette lighter power cable to achieve this.


Plug the end of the oxygen sensor data cable into the marked port on the LM1 unit.

Before we place the wideband O2 sensor in the exhaust we will perform the required calibration. Connect the sensor to the data cable and hold or place the sensor in the air. It will be heated so do not touch or place anything in contact with the metal part of the sensor.

Press and hold the "Calibrate" button until the display indicates it is calibrating. This calibrates the LM1 to the wideband O2 sensor and only needs to be done the first time the sensor is used.

When the calibration is complete the unit will read the O2 content of air, about 20.7%.


The wideband O2 sensor can now be installed into the exhaust. Unless you have a need or desire to monitor air-fuel ratio constantly, our recommendation is to only use the wideband sensor when you are tuning, then remove it and use the supplied pipe plug to close the hole. This will maximize the life-span of the sensor. Replacement Bosch sensors are about $80 through Innovate.
With the wideband sensor installed in the Montego's exhaust, we routed the wiring along side the door and secured it with electrical tape. Clearly this is temporary install since once the carburetor is tuned we would remove the LM1 from the vehicle. For permanent mounting guys often route the cable up through a hole drilled in the floor pan. Innovate offers a variety of permanent mount accessories, including the XD-16 digital gauge.

The next step is to hook-up the RPM module (also termed the LMA-2). We cut some wire to run from inside the car through to the engine compartment. One end goes to the terminal marked RPM on the LMA-2 as shown.
The other end of the wire needs to tap into a tachometer feed, such as the dedicated terminal on the D.U.I. distributor shown, or the tach output on an MSD box. On a stock ignition system you can use the negative side of the coil or tap into the factory tach wiring if so equipped.

Plug the RPM module into the LM1 port marked AUX IN. Before we fire up the engine we need to set the RPM module to reflect the number of cylinders in the engine.
Setting the RPM module is performed using the supplied software and 3.5mm audio cable. You can take the RPM module over to your desktop computer, or use a laptop as we have done. Install the software and fire up the LM Programmer utility. Follow the on-screen instructions for setting your modue for a V8 four-stroke engine.


(Start Tuning and Stop Guessing)


In This Article:
FordMuscle uses the Innovate Motosports LM-1 Digital Wideband Air/Fuel Ratio Meter to tune our carbureted 1972 Mercury Montego. We prove that tuner technology isn't just for the EFI and import crowd.

Our Project MX Montego is nearly a second faster in the quarter mile with less than an hours worth of carburetor tuning using the Innovate Wideband Tuning System.


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, 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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