Emissions Tuning Fundamentals: Driving Behaviour
Watch This Course
$299 USD
-OR-
Or
8 easy payments of only $37.38 USD
Instant access. Easy checkout. No fees.
Driving Behaviour
02.58
| 00:00 | When it comes to a lab test, at the OE level, sometimes robot drivers are used. |
| 00:04 | Their programming can be tweaked not only for optimal results, but consistent ones. |
| 00:10 | Aftermarket compliance certification requires human drivers though and R&D testing in the aftermarket generally uses human drivers to keep costs down. |
| 00:20 | Most individuals and companies can't afford a robot driver but they're not needed to succeed, we just need to remember that driving behaviour has a significant impact and to do our best to control and monitor it. |
| 00:33 | When we talk about driving behaviours, some specific items that can increase emissions are aggressive accelerator pedal transitions, both moving the pedal down as well as releasing it, aggressive acceleration, driving at high speed, selecting lower gears which can cause higher engine speed and short trip driving rather than longer drives. |
| 00:55 | First let's talk about transient conditions. |
| 00:58 | A properly tuned engine should operate on its lambda target during any steady state condition but transitions of throttle and load can be more challenging and may cause increased emissions due to temporary air fuel ratio target error. |
| 01:12 | Next, as we've mentioned already, higher engine load tends to increase emissions so aggressive acceleration and driving at high speed both fall under that concern. |
| 01:21 | Keeping the engine at higher RPM increases frictional as well as thermal losses. |
| 01:27 | This creates more heat which can result in increased NOx emissions or require fuel mixture changes for protection that negatively impact hydrocarbon, carbon monoxide and carbon dioxide production. |
| 01:39 | We're including short trip driving in this list simply because the shorter each drive is, the higher the percentage of the total drive is being performed without the engine catalysts and drivetrain warmed up to operating temperature. |
| 01:53 | If you perform the same drive starting with the vehicle cold versus warmed up, results will differ in terms of emissions per mile with the cold vehicle emissions being greater, especially during the first several seconds of operation. |
| 02:06 | For this reason, it can be helpful to consider cold vehicle emissions separately from warmed up emissions and we'll get deeper into that later. |
| 02:15 | For now let's recap the key driving behaviours that impact emissions. |
| 02:19 | Emissions are reduced when the driver actuates the accelerator pedal smoothly. |
| 02:24 | Greater emissions can occur during aggressive acceleration or sustained higher RPM operation. |
| 02:31 | Driving at a high speed may also increase emissions but modern vehicles tend to remain clean within the realm of speed limits found in most countries. |
| 02:40 | Because the engine is in warm up enrichment for a higher percentage of short trip drives compared to longer drives, emissions measurements taken on a per total time or grams per mile basis will generally be higher on short drives. |
