Computer & Emissions Controls in Savannah GA
Controller Area Network
Your car may be ugly, but it’s not dumb thanks to what’s called the CAN or “Controller Area Network.” Operating a motor vehicle has gotten a lot easier, cheaper and more efficient because of the streams of data flowing around your car whenever it’s running. Every new model year introduces more innovation that depends on the distributed electronic brains and sensors peppering almost every nook and cranny of your automobile.
The CAN acts like a master conductor, coordinating and regulating signals from the myriad of ECU’s (Electronic Control Units) scattered throughout the engine compartment, body, suspension and exhaust systems. Every ECU has a limited number of specific jobs to do, like rolling up a window, adjusting oil pressure or managing the temperature of the transmission. In order to do their jobs in sync with each other, the ECU’s need lots of information about the current conditions that may have an impact on its job at any given moment.
That’s where the CAN comes in. It accepts and distributes data from all the sensors- up to 100 of them in current models, and that is expected to double in the near future. That data is then circulated to all the ECU’s so they can make their local decisions in response. It’s all data, all the time, and the ECU’s pick and choose which signals they need to “listen” to.
For example, your brakes.
If you have an anti-lock braking system on board, it has an ECU that’s tied into the CAN called the Electronic Brake Control Module. Before telling the system to turn on, it needs to know a number of conditions from other systems in the car, namely:
- The brake pedal- is it being pushed down? How hard? How fast?
- Is the car in Four Wheel Drive mode?
- Is the engine running? Check the ignition key position.
- How fast are we going?
- What’s the wheel speed of each of the four wheels, and how does it compare to our actual moving speed?
Based on all those factors picked up by sensors and made available via the CAN, the automatic brakes give you that pulsing sensation as you try to stop on a wet or icy road.
Before CAN was introduced, cars got ridiculous in the amount of copper wiring they needed. For every new added feature was a dedicated wire that ran from the device to a dashboard switch. The result was a super-complex wiring scheme that added weight and repair headaches.
Can replaced that physical complexity with programming complexity. Devices got smarter and made thick bundles of wire unnecessary. That also has ramifications for the auto repair industry which has had to keep up with increasingly computerized systems in every car. Our ASE certified technicians spend a lot of time and effort to stay current on the latest types of sensors and computing units, including some wireless sensors that communicate with the CAN.
One of the issues these electronics has helped with is pollution controls from car exhaust. Since the clean air act of 1977, the emissions of carbon monoxide and oxides of nitrogen have steadily decreased, helped by electronic feedback systems that self-regulate the byproducts of hydrocarbon-based fuel used for combustion in your engine.
There are several important devices that are found on most cars now, all tied in with the car’s network of data flow.
Catalytic Converter (CC)
Did you know these guys are the reason all gas is unleaded now? Leaded gas was found to coat the surfaces of inside the CC and render them ineffective. The CC “cleans” your exhaust by allowing it to flow over baffles or pellets made of platinum or palladium. These materials catalyze a rapid oxidization of the gases that flow through it, resulting in safe carbon dioxide and dihydrogen oxide (water)
Otherwise known as the Positive Crankcase Ventilation system, it’s job is to recycle any unburnt fuel-air mixture by injecting it back into the combustion chamber (cylinder) for burning. A malfunction here could cause vapors to back up into the air filter, rough idling, or at its worst, wrong pressures will break engine seals and cause oil leaks.
The Exhaust Gas Recirculation valve, like the PCV, meters a small amount of exhaust back into the combustion chamber to re-burn it and clean the exhaust gas bit more. Since the internal combustion engine isn’t designed to run on exhaust gases, it only does its job when the engine is fully warmed up or doesn’t need full power.
A series of design elements that prevent the evaporation of gasoline fumes into the atmosphere. The gas tank cap, along with a charcoal canister, a purge valve and the proper level of engine-created vacuum work together to prevent pollution at the gas station.
Three factors are always in play for actual combustion to take place- heat, fuel and oxygen. In your exhaust system, while the engine is running, there’s plenty of heat plus a little unburned fuel. Adding a bit of oxygen makes it ignite and burn, further reducing harmful emissions. Air injection is done after the engine is finished getting its power from the fuel-air mixture so this last burn has no effect on the performance of your car.
We speak computer-ese here at Integrity Automotive, so there should be no problem finding out about any issues your car may have, especially if the check engine light is on. Bring ‘er in and we’ll check for any problems with sensors, ECU’s or emissions control devices.