Method and system for adjusting a fuel tank isolation valve
First Claim
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1. An engine method, comprising:
- via a controller;
adjusting a fuel tank isolation valve (FTIV) of a fuel system by sending electrical pulses to the FTIV;
counting each of the electrical pulses to track a position of the FTIV;
applying a vacuum to force the FTIV to a known closed position;
verifying the closed position of the FTIV in response to sensing the applied vacuum in the fuel system; and
following verification, actuating the FTIV to a desired position based on the verified position and engine operating conditions by sending further electrical pulses.
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Abstract
Methods and systems are provided for adjusting and diagnosing a position of a fuel tank isolation valve of a fuel system. In one example, a method may include adjusting the fuel tank isolation valve via electrical pulses and tracking a position of the FTIV by counting each of the electrical pulses. When a vacuum is created in the fuel system, the method may include verifying the position of the FTIV based on resulting fuel system pressures.
11 Citations
20 Claims
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1. An engine method, comprising:
via a controller; adjusting a fuel tank isolation valve (FTIV) of a fuel system by sending electrical pulses to the FTIV; counting each of the electrical pulses to track a position of the FTIV; applying a vacuum to force the FTIV to a known closed position; verifying the closed position of the FTIV in response to sensing the applied vacuum in the fuel system; and following verification, actuating the FTIV to a desired position based on the verified position and engine operating conditions by sending further electrical pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for an engine fuel system, comprising:
via a controller;
tracking a position of a fuel tank isolation valve (FTIV); andduring a first condition when the position of the FTIV is known, adjusting the position of the FTIV based on engine operating conditions from the known position; and during a second condition when the position of the FTIV is unknown, applying a vacuum to the engine fuel system and the FTIV to force the FTIV to a known closed position and verifying the closed position of the FTIV based on detection of the vacuum. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A fuel system, comprising:
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an engine; a fuel tank; a canister for storing fuel vapors; a fuel tank isolation valve (FTIV) coupled in a vapor line between the fuel tank and the canister, the FTIV held in both opened and closed positions without any applied current; a leak check module including a reference orifice, a vacuum pump, and a pressure sensor; and a controller with computer readable instructions for; applying a vacuum to the fuel system via the vacuum pump to force the FTIV to a known closed position; and diagnosing the closed position of the FTIV based on fuel system pressure after applying the vacuum and subsequently adjusting the FTIV based on the diagnosed position and engine operating conditions. - View Dependent Claims (19, 20)
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Specification