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What readings can I expect from a diesel exhaust? |
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The exhaust gas readings from diesel exhausts very widely dependant on the type of engine management system.
A five gas analyser will accurately measure the following gases: Oxygen, Carbon Dioxide, Carbon Monoxide and Oxides of Nitrogen (NOx).
It will also measure Hydrocarbons (HC) but because the analyser's response is optimised for hexane, the HC readings from a diesel's exhaust will be inaccurate (very low.. maybe only 5% or so of true HC reading) and should be discounted.
Note: To create representative levels of NOx, the engine must be under load.
Examples: ..not necessarily typical, just random measurements.
Normally aspirated diesel engine at idle:
| ... |
Tuned |
Mis-Tuned |
O2 |
1.5% |
0.3% |
CO2 |
13.5% |
10.2% |
CO |
0.5% |
6.0% |
Turbo diesel at idle:
... |
Tuned |
O2 |
14.9% |
CO2 |
5.1% |
CO |
0.02% |
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