Alex Portillo is the head technician of Car Clinic, a state-of-the-art automotive repair facility in Mahopac, N.Y. He is a protégé of Jerry Truglia and has been trained by Automotive Technician Training Service and is TST certified. Alex’s real-world, in-depth diagnostic articles will appear in Auto Service Professional on a regular basis.
Emission analyzers have been under-utilized pieces of equipment in our industry for years. Many shop owners and technicians think that the emission analyzer is only used for vehicle inspections rather than using it for diagnosing vehicle drivability problems. Their short-sightedness is preventing them from diagnosing many vehicle problems in a shorter period of time.
In this article I’ll explore the different ways that the five-gas analyzer can make your job easier and more profitable.
The old Sun diagnostic saying “Test Not Guess,” is what you will be doing when you use a five-gas analyzer in your diagnostic routine. Keep in mind that the five-gas can be used both on old and new vehicles, for all different systems from cooling to EVAP and a bunch more in between.
We should first do a quick review on what the five gases are so we understand what we are looking at and for. For seasoned techs this will be a simple review. For the newer techs, or for those that have not worked in a shop with a four- or five-gas analyzer, this will serve as an eye-opener.
You will be happy to know that I am not going to get into a lengthy explanation of the molecules, but rather just what you need to know.
Let’s start with the main ingredient HC that makes it all happen along with air. HC is the abbreviation for hydrocarbons, which is unburned fuel. Our next ingredient is O2 (oxygen), which is what we breath and what the engine needs to burn the HC. As a result of the burn/combustion, CO (carbon monoxide) is produced that is a by-product of incomplete combustion.
Now with three down and two to go, it’s NOx up next, which stands for oxides of nitrogen which are formed in the combustion chamber when temperature exceeds 2,500º Fahrenheit — you know, the pinging sound. Engine manufacturers have installed EGR (exhaust gas recirculation) valves on engines for years but they have a tendency to cause problems from stalling to no starts. So they came up with VANOS (Valvetronic Variable Valve Lift System), first used by German manufacturers, eliminating the use of an EGR valve while still lowering NOx emissions.
The fifth, CO2 (carbon dioxide), is the final one which I like using as a diagnostic tool that helps me decide if the engine is running to it optimum efficiency. Keep in mind that CO2 is an indicator of combustion and catalytic converter efficiency.
So there you have a painless review of the five gases. Now it’s time to move on and explore what the information can be used for in the shop bays.
I am going to start with inserting the five-gas probe into the tailpipe of a vehicle and use the readings as a diagnostic tool. The results of how efficient the engine and catalytic converter are will appear right on the screen in seconds.
Take a look at the following reading and see if you can diagnose what the problem may be on this hypothetical vehicle’s emission readings:
HC 350 PPM (idle), 310 PPM (2,000 rpm), CO 3.5% (idle or 2,000 rpm), CO2 = 8-10% (idle or 2,000 rpm), O2 0.2% (idle or 2,000 rpm), Lambda 0.97.
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