"Let's start out with some simple questions on 5-Gas Exhaust Analysis for review, then we'll get into the more complex questions. Let's assume the catalytic converters on the cars in the test are not real good, maybe only 50% efficient. If we had really good cats, no matter what the problem the cat could clean it up for a while, and we wouldn't see any emission problems coming out the tail pipe. And please keep in mind that in real life these emission readings would vary a lot depending on the exact vehicle being tested. You may have seen one in the shop yesterday that was different. Just think about the general concept or theory involved in the test question.

1. A simple problem like a spark plug wire that fell off will likely cause lots of which pollutant to come out the tailpipe? Let's assume the engine is a non-feedback engine, or it stays in open loop.

A: NOx
B: CO2
C: CO
D: HC

2. If an EGR valve functioned properly and came open, but the passage was clogged with carbon, which pollutant would likely be high in a loaded mode test on a dyno?

A: CO
B: HC
C: NOx
D: CO2

3. High numbers of NOx come out the tailpipe when Vehicle A had it's dyno smog test. Which of the following conditions could cause this?

A: An ignition misfire from a shorting spark plug wire
B: Too much carbon inside the combustion chamber
C: A bad thermostat that causes the engine to run hotter than normal
D: Both B and C

4. Let's say an engine puts out these readings at the tailpipe: HC 459 ppm, CO 4.7%, CO2 10.3% and O2 0.1%. What do you think is going wrong with this engine?