A diagnostic Tool designed by LENEHAN RESEARCH www.lenehanresearch.com 1-949-472-1026 "Real Time Monitor was produced to show the operation of the most important feedback sensor on today's gas engines - the oxygen sensor. Many scanners cannot show this output, which oscillates at better than ten cycles per second, because of slow update times." (Information supplied from the Lenehan Research website) Package contents: Real Time Monitor, yellow re-usable ties, 2-AA batteries, O2 sensor jumper leads, storage box, bubble wrap pouch, instruction manual, warrantee card. A Product Review By: Bruce Bonebrake Managing Editor at BAT AUTO I am going to do this tool review in two parts. In order to understand the capabilities of the Real Time Monitor you will first need to realize what the O2 sensor does and why this sensor operation is very important. I am going to go over the O2 sensor first, and then we will put theReal Time Monitor to the test. The O2 sensor is the short term used for the Oxygen Sensor. Since the early 1980's the O2 sensor has been used as an input device for the "On-Board" computer system. There have been several design changes in the computer systems, but the O2 sensor, has remained virtually the same. The computer system is designed to control several different systems on the vehicles of today. When first introduced, the computer controlled the spark timing and the fuel management. Some early systems controlled the spark timing only. The O2 sensor is one of the main components required for the computer to be able to control the fuel management. OK, let's talk about what an O2 sensor does. An entire article could be done on this subject, but I want to briefly explain what the O2 sensor is. In the exhaust system is where the O2 sensor will be located. Some vehicles/engine designs will place the O2 sensor directly into the exhaust manifold. Other vehicles may locate the O2 sensor in the exhaust pipe. The farther the O2 sensor is from the heat source, (which would be where the exhaust exits the engine) the longer it will take to get the O2 sensor at operating temperature. On some applications, this can never be achieved without an alternate means of "pre-heating" the sensor. On these applications, the O2 sensor will be equipped with an internal heating element. These types of O2 sensor can easily be identified by the multiple leads attached to the O2 sensor. A "non-heated" O2 sensor will be equipped with a single wire connection or in some cases, 2 wires, and the second wire being a ground for the sensor. A one-wire sensor relies in the O2 sensor mounting for ground. How does the O2 sensor work? Very simple actually. The "tip" of the O2 sensor is Zirconia/Platnium. The tip is placed into the exhaust stream, and is able to monitor the amount of Oxygen that is contained within the exhaust. The O2 sensor must reach 600 degree's F (316 degrees C) in order to function correctly. When the O2 sensor is at operating temperature, it will then be capable of producing voltage. The O2 sensor will create voltage from .1V to 1.0V. When the voltage is low (.1V-.45V) the O2 sensor is sensing a Lean condition. When the O2 voltage is High (.45V-1.00V) the O2 sensor is sensing a Rich condition. Sounds complicated, but I can tell you a way to easily remember what voltage is Lean. When the engine is off, no exhaust, the O2 sensor will be producing .0V. As you know, the exhaust system will be 100% Oxygen when the vehicle is not running, ok, well, there may be some residual exhaust lingering in the exhaust system, but, you get the point. Lean=Low voltage produced by the O2 sensor. Why go through all of this? Simple. To obtain what has been determined as the "perfect burn" 14.7-1. To achieve this, the system will have to monitor the burn, and make necessary changes. The center, or Reference Voltage of the O2 sensor is .45V, which, you guessed it, the perfect burn 14.7-1. The voltage produced by the O2 sensor is sent to the computer, and the computer interprets the voltage, and will lean or richen the fuel the carburetor or fuel injector's supply, to run the engine. So, the O2 sensor "tells" the computer the engine is running Lean and the computer will then command the fuel system to go Rich. This Rich-Lean cycle is constantly being repeated in Milli-seconds. Due to this, it is almost impossible to "read" the voltage, or what the O2 sensor is "sensing" at a certain given time. This cycling is so fast that the computer will look at how many times the O2 voltage has crossed the computers .45V reference point. The computer will display this as "Cross-Counts". In order to be able to read this fast signal produced by the O2 sensor, until now, a Lab Scope would have been required. This tool, Real Time Monitor displays, in "Real Time", what the voltage (information) the O2 sensor is sending to the computer. This information is vital to the repair technician. The "health" of the O2 sensor, the ability to quickly recognize a change in the fuel control, and verifying the system is working properly are key factors for the engine to run properly and efficiently. One "Myth" that commonly occurs, is that a "Lean" or "Rich" O2 sensor fault code that is set by the computer is an indication that the O2 sensor has failed. The O2 sensor is then replaced, and the ACTUAL problem could still be present in the system. Any problem that can produce an overly rich or lean condition can cause the code(s) to set. With the Real Time Monitor the O2 operation can be monitored in the "Real Time" mode. For the test vehicle, we are testing a 1987 Olds Cutlass Cierra. This vehicle is equipped with a 2.5L 4 cylinder with TBI (Throttle Body Injection). This vehicle was brought to my shop to check out and repair multiple problems. I am going to use theReal Time Monitor to verify the fuel management system is performing properly. The main performance problem the vehicle experienced was a lack of power, and an intermittent miss-fire. A visual inspection showed a severe valve cover gasket leak. The oil leak filled all 4 of the spark plug recessed cavities with engine oil. Under a slight load, I could easily see the stray spark from #3 and #4 spark plug wires arcing to the cylinder head. A quick phone call to the owner, and we both agreed to replace the spark plugs, spark plug wires and degrease the engine and replace the valve cover gasket. The pictures to the left show the work in progress and the location of the O2 sensor. The O2 sensor is located on the exhaust manifold on this application. This is a single wire "non-heated" O2 sensor. (On our test vehicle (picture above and below), you can clearly see the O2 sensor, which is mounted into the collector area of the engine's exhaust manifold.) The vehicle hook-up is very simple and straight forward. As with the What Quits First? tester that Lenehan Researchdesigned, the Real Time Monitor vehicle leads are permanently secured into the body of the tester. There are 4 leads total. The lead quality is EXCELLENT. The O2 sensor leads and Ground lead are Teflon coated to resist the extreme high temperature. Every detail of the tester has been thoroughly thought out to provide a tool that will provide years and years of trouble free service.