Real Time Monitor A Lenehan Research Product


Staff member
Nov 13, 2006
A diagnostic Tool designed by

"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.


Staff member
Nov 13, 2006

Hooking the tester to the vehicle:
First, locate the O2 sensor, and disconnect the harness connector for the O2 sensor (usually located 12"-24" in the wire attached to the O2 sensor). Now to attach the vehicle leads:
---The White lead attaches to the wiring harness end of the connector.
---The Red wire attaches to the O2 sensor end of the connector. ( Note: The supplied adapters pictured in the lower picture, have multiple pin sizes and configurations to choose from. Select the adapter that matches the connector terminals. The other end of the adapters connect to the Red and White wires of the tester)
---The Black lead connects to a good ground. I would recommend attaching the lead to a good clean metal location on the engine.
---The final lead is a sensing bulb that is secured in a shrink tube. The sensing bulb is placed next to the injector body. On the 2.5L this is a single injector throttle body style so, the sensing bulb is placed along side the injector, and with the supplied ties, I secured the bulb in place (picture below)

To set up the tester for operation, requires that the batteries (2-AA batteries-included) be installed in the tester. This is a simple task. Merely slide off the battery compartment cover, and install the batteries noting the polarity, which is clearly marked inside the tester.)

(The adapters needed to connect to the O2 sensor wire and the harness to the sensor wire are included. Due to the different terminals that could be used, included with the tester,are several connector configurations that will fit virtually any pin design. I was VERY impressed with the adapters. Well designed, and they work)

(CAUTION: When installing the sensor on a "Throttle Body Equipped" vehicle make sure to tie the sensor wire to the throttle body!! When doing this, double check to make sure the sensor or the wire tie will not be able to come loose and fall into the throttle plate!!)

Ok, we have it connected to the vehicle. Lets go over how the Real Time Monitor is designed. On the front of the tester, there is a "membrane" touch pad with several function buttons. Also, there are a total of 12 -SUPER BRIGHT LED's. I have highlighted some of the functions on the picture on the right.
The LED's can EASILY be seen in direct sunlight, as shown in the picture below. At the time of the testing the sun was directly above me and the LED's were very easy to see. I stood 15' away from the tester and the LED's were plainly visible.
The touch pad is very sensitive. It takes a couple of seconds to decide if you really depressed the buttons. They are not "tactile" so you will not feel a click. They only require a light touch to make the function perform. Another feature I REALLY liked, was that it requires pressing the MODE button and a FUNCTION button at the same time to make a function perform. Same goes for turning the unit off. This is excellent because you cannot accidentally touch the touch pad, and stop what you have the tester currently performing, or accidentally turn it off.

On the left, I have went into detail what the 4 functions are and were their use would be helpful.

There are 4 modes the tester can operate in:

1)."O2 MON"- This function will show the O2 operation in real time while in "Closed Loop". If the O2 sensor is operating properly, you will see the LED's oscillating above and below the center line (marked on the tester 14.7-1= .45V reference voltage). If the oscillating of the LED's is slow, this could indicate a weak or defective O2 sensor.

2)."O2 SIM"- This is a GREAT function!! I really was impressed with this!! The O2 SIM mode, shows the mixture above or below 14.7-1 (.45V) in "Open Loop". In open loop the computer can be controlled by the "GO RICH" or "GO LEAN" buttons. This function alone, makes this tester invaluable when testing the system. When the tester is in O2 SIM mode, and the GO RICH button is depressed, the "Simulated" O2 voltage sent to the computer will be low (0.05V) Full LEAN. When the GO LEAN button is depressed the O2 voltage sent to the computer will be high (0.90V) Full RICH. Ok, why is this important.. the computer will see the lean or rich signal from the (simulated) O2 sensor and should command the system either lean or rich.
For example, if the GO LEAN button is depressed, a high volt (RICH) signal is sent to the computer and in return the computer will command the fuel system LEAN.
The other way, if the GO RICH button is depressed, a low volt (LEAN) signal is sent to the computer and the computer would command the fuel system RICH. When performing the test, simply watch the LED's and see if and how long it took the computer to make the necessary change. This is impressive. I really worked with this. Several things impressed me about the tester, but this function is very nice to have at your fingertips.

3). "INJ MON" This is another EXCELLENT feature of this tester. When the tester is placed in this mode, the injector pulse can be seen by the LED's and will be around the center of the tester. When the engine is revved up the higher LEDS will illuminate and during deceleration the lower LEDS will illuminate. This is a "window" into the injector operation. There are several uses for this feature. One GOOD use that comes to mind, would be checking the injector(s) to see if they are operating. On a "Muti-Port" injection system, it would be simple to connect the tool to one injector at a time, and compare the operation of each injector using this function. Alot of possibilities here.

4). Lastly, the 4th function is simply turning the tester off.

The picture below, shows the Tester in use on Jon's 1987 Olds Cutlass Ciera. I was able to take some time and use the tester on the vehicle for about an hour. The vehicle is in EXCELLENT condition. The O2 sensor is active and the computer is quick to recognize a change made by the O2 SIM test (explained on the right).
Jon was very glad to hear the good news and hopefully will have several thousand more miles before any repairs will be needed.

(In order to fully appreciate the tester while in operation, you would need to have a video camera, and tape the operation in progress. The LED's are active during the operation and tests. Nice "light show" (grin)

In closing, I want to rate this tester and its usage.

product review rating by Bruce Bonebrake
Overall design..........................................................EXCELLENT
Instructions included for use....................................EXCELLENT (detailed, simple to use owners manual included)
Lead design and quality...........................................EXCELLENT
Packaging.................................................................EXCELLENT (thin box for contents will fit any tool box drawer)
Includes necessary accessories?............................YES (jumpers, batteries, instruction manual, warrantee card)
Setup........................................................................EXCELLENT (5-20minutes depending on O2 sensor location)
Contact information for company..............................EXCELLENT (included on the rear cover of owners manual)
Level of experienced required for use......................Designed for the Professional mechanic/technician (However a serious DIY'er would benefit greatly by using this tester)

In closing, thank you LENEHAN RESEARCH for the great job you folks are doing there!! With your excellent understanding of how difficult today's vehicles are to properly and correctly diagnosis, and the engineering that has went into the two products you currently sell ("WHAT QUITS FIRST?" and "REAL TIME MONITOR") , helps to make those in this field, jobs more professional!
Thank you!!

Bruce Bonebrake
Managing Editor of BATAUTO