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For the next several seconds, the injector pulse width is wider than normal to provide sufficient fuel for starting. Idle control is performed by adjusting a stepper-motor-driven bypass valve in the intake plenum. When the ignition is switched off, the ECU winds the bypass valve fully open to provide enough air the next time the engine is started.
The result is an engine that fails to maintain idle RPM and frequently stalls. A jammed actuator may be freed simply by cleaning it. However an actuator that has stopped working due to a fault in its servomotor will need replacement. Air leaks in either the stepper housing or pipes will cause elevated idle RPM.
Most air conditioning-equipped engines have an automatic adjustment feature in the carburetor or fuel injection system that raises the idle when the air conditioning is running. Engines modified for power at high engine speeds, such as auto racing engines, tend to have very rough (unstable) idle unless the idle speed is raised significantly.
The sound produced by compressor surge is called turbo flutter and the repeated, high speed cycling will cause a cyclic torque on the compressor and may lead to increased stresses on the bearings and compressor impeller. [2] A blowoff valve is designed to release pressure in the intake system when the throttle is closed.
Afterburner-equipped engines may also open the nozzle for starting and at idle. The idle thrust is reduced which lowers taxi speeds and brake wear. This feature on the J75 engine in the F-106 was called 'Idle Thrust Control' and reduced idle thrust by 40%. [28] On aircraft carriers, lower idle thrust reduces the hazards from jet blast.
There's a new No. 1-ranked player in the transfer portal. Washington State quarterback John Mateer is entering the transfer portal, Cougars coach Jake Dickert confirmed Monday. He's the No. 1 ...
Mortgage and refinance rates for Dec. 19, 2024: Average 30-year, 15-year rates move higher after Fed's quarter-point cut
Compressor surge is a particular problem during slam-accelerations and can be overcome by suitable adjustments to the fueling schedule and/or use of blow-off (bleeding air off the compressor, for handling purposes). In the particular example shown, a slam-acceleration from ground idle would cause a high-pressure compressor surge.