【正文】 P to help the work of the air control valve, (3) access to fault codes, engine temperature sensors detect abnormal changes should be made, (4) the engine temperature sensor connector will be disconnected after the startup engine, If normal, check the temperature sensor circuit and sensor, (5) to check whether the plug voltage regulator tube. (B) no engine fast idle 1, maintenance examples Vehicle: Chrysler Fault phenomenon: when idle or fast idle instability and on the 25th when the fault code, fault code on the 25th will CHECKENGINE lights. Fault reasons: (1) check the throttle body wire harnesses, tape tied observation of whether any part of the damaged insulation. (2) electric wire harness will be placed in jail beam PCV valve cover joints. (3) If the fault code exists on the 25th, the use of SCANNER red box directory CLEARCODES clear fault code, if the fault code again, is the idle speed motor may be surmised that a bad or loose wiring. 2, the engine no faster Idle Fault Detection and Diagnostic Analysis 1) fault phenomenon Start the engine and no fast idle. 2) the cause of the malfunction Ignition System: ignition timing inaccurate. Intake System: (1) whether the bypass plug into the trachea (2) auxiliary air control valve is not working correctly. Control systems, engine water temperature sensor bad. 3) diagnostic methods (1) check the auxiliary air control valve work is normal and its circuit, (2) to check whether the plugpass into the trachea, (3) check and adjust ignition timing, (4) Unplug the vacuum tube regulator to regulator provide vacuum or pressure, check the mixing ratio feedback sensor system, (5) Unplug the connector engine temperature, and then restart, if it is not normal, check the sensor and its circuit. (C) warmup before the engine idle speed instability 1, repair examples: Vehicle: Toyota Crown Fault phenomenon: after starting running cooler, the idle running unstable. Adjust idle speed screw, fault still exists. Fault Analysis and discharge: the car equipped with a diagnosis of electronic control devices. Available for their inspection Failure, is: Open bon, in the vicinity of air intake manifolds to find a box marked with the Diagnosisde. Open the diagnosis of plastic cover, in its socket to find the back of the jack TE1 and E1. With a short wire to connect the two jacks, and then placed in the ignition switch ON block, at this time do not have to start the engine, do not have to pedal, so that throttle to maintain in situ. Fault dashboard warning lights began flashing regularly 4 times and one times, that fault code 41. Check out the information that has throttle position sensor fault. Car throttle position sensor output for potentiometertype structure, there are four posts, namely Vc (power pin) IDL (Idle feet), VTA (output pin) and E2 (grounding pin). Check the sensor wiring found broken off, but check the connector found on it has corroded. Rust on the connector, the circuit back to normal. Start the engine, and then finetune idle screw, and its speed can be stabilized at around 750r/min, the elimination of puter memory, and then show the code review of puter failures, fault display code no longer appears that the fault has been ruled out. Finally removed the diagnosis box on the wires can be short, the car throttle position sensor with the throttle while turning the potentiometer to change the variable resistor, the controller changes the voltage signal from that a throttle opening and position. If the throttle position sensor short circuit or open circuit will cause the engine difficult to start, idle, or flame instability. 2, engine warmup before the idle instability analysis of fault detection and diagnosis 1) fault phenomenon Start the engine running after the cooler, the idle running unstable. 2) the cause of the malfunction Intake System: (1) mixture concentration, auxiliary air control valve. Ignition System: ignition timing inaccurate. Control System: Engine water temperature sensor bad, EGR System: EGR control valve jammed shut down should not, EGR solenoid valve often broken. 3) diagnostic methods (1) the use of ignition timing light to check the engine ignition timing, (2) check the auxiliary air control valve work is normal, (3) Unplug the oil pressure regulator vacuum tube to the regulator to provide vacuum or pressure,