Auto and Truck Repair and Advice
Serving the Gainesville and Hawthorne Florida Area
Automotive Fuel Injection
A computer measures engine conditions and precisely sprays an exact amount of fuel into the intake manifold through FUEL INJECTORS.,
WHAT GOES WRONG
The FUEL PUMP, FUEL FILTER, COMPUTER, AND ALL ITS SENSORS AND WIRING can make the fuel injection system fail. Individual injectors can become clogged with rust, varnish, etc. All systems have a pressure regulator, since fuel injection systems rely on very constant and accurate fuel pressure to operate properly. If the pressure is too high, the car will run rich.(Black smoke!) If pressure is too low, it will run lean or will not run at all!
ELECTRONIC COMPUTER CONTROLLED FUEL INJECTION
An electric solenoid is opened by the computer. The amount of fuel is controlled by how long the solenoid is kept open.
TYPES OF COMPUTERIZED FUEL INJECTION
THROTTLE BODY FUEL INJECTION
It's the simplest way to do fuel injection. A fuel injector sits on top of a throttle plate. Looks like a shower head.
It opens 10 times per second regardless of engine conditions or rpm. The computer keeps it open longer or shorter times to vary the fuel to air mixture
MULTIPORT FUEL INJECTION
Here you have an injector for each cylinder. Often these injectors are also pulsed 10 times per second and kept open longer or shorter times to vary the fuel to air mixture
SEQUENTIAL FUEL INJECTION
Sequential injection doesn't fire all the injectors at once, although often they will only fire in a set of two (half the cylinders get a squirt of gas, then the other half, etc.) Even the most advanced sequential injection systems operate each cylinder's injector twice for each combustion cycle. (once on the intake stroke, once on the power stroke). The fuel sprayed each time is equal. The fuel sprayed during the power stroke is "stored". It cools the valves off, vaporizes, and gets sucked in along with the next injector spray, when the intake stroke comes around again.
CONSTANT FLOW FUEL INJECTION
The earliest gasoline fuel injection was constant flow. A mechanical linkage moved a calibrated rod in an orifice. This metered fuel to injectors at each cylinder. A throttle plate metered the air.
BOSCH CIS
A neat fuel injection system, Bosch CIS is found on all the Rabbits, some Volvos, and a bunch of other European rides.
A hose connects the intake to the CIS fuel control assembly: often holding the air filter. A round plate blocks the airflow. As the engine sucks in air, this plate lifts up. It opens a valve, which sprays more and more fuel to the injectors at each cylinder as the plate lifts up. These injectors spray all the time the engine is running.
The Economechanix Cyber Mall
We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry!
Thank you for visiting the ECONOMECHANIX WEB SITE. Please feel free to comment. We also serve the surrounding communities of Alachua, High Springs, Hawthorne, and Newberry! Gainesville has been my home since 1974, and I've loved Gvl and the Gators since I came here in the fall of 1974 to attend the University of Florida. I loved it so much I stayed and opened my car repair business. Originally it was out of the back of a 1963 Chevrolet wagon, but in 1977 a fellow mechanic and I opened an auto repair shop with actual walls, etc. I stayed in the same location for 26 years, and recently moved my operation to property I bought 15 miles east of Gainesville. I am doing most all the repairs myself now, having reduced my overhead from $1500 per month to practically nothing. I do work by appointment only. I mostly work only on my established customers cars, but I will occasionally take on new clients. E-mail me and I will either make arrangements to look at your car, or I will recommend you to someone who will.
George G. Scott, Jr.