1, symptoms and preliminary diagnosis
High pressure cleaning vehicles after starting the engine at low speed instability, the situation is easy to stall when idling in three ways:
1.1 Rough idle at normal temperature under.
High pressure cleaning car engine idle speed instability 1.2 when cold.
1.3 idle instability during warm-up.
Faulty 1.1 Analyzing the situation: this failure should first consider the three basic conditions of operation of the engine and exhaust gas purification device working poor, poor squib work or other reasons (including the spark advance means), they can cause unstable idling.
Faulty judgment of the case 1.2, 1.3: Failure Cause should expect in connection with the temperature and the presence of 1.1; when the engine is cold, check the carburetor choke and the degree of opening at high idle speed, the low speed nozzle has no plug, the oil spill phenomenon; the engine warm state, check the oil level is too high, the idle work compensation means nondefective and engine overheating.
2, diagnostic methods and procedures
2.1 Basic Checks: Check the high-pressure cleaning vehicle ignition system; check choke choke and high idle opening, check the carburetor oil, idle speed, ignition timing.
2.2 working conditions exhaust gas purifying device: EGR check; check the ignition timing control means; CO, HC concentration detection.
2.3 Check valve clearance: timing gear wear, timing belts and timing chain elongation; valve clearance is too large.
2.4 check the cylinder pressure: Check the cylinder head gasket; check the cylinder pressure is low (in general reasons pistons, piston rings, cylinder bores, valve, valve seat).
The following examples illustrate the vacuum gauge to determine the cause of the fault inspection method:
High-pressure cleaning truck engine idling pointer should stand still 50cmHg above. When fully open the throttle quickly turned from the fully closed, fell 60cmHg pointer over non-normal position.