Geely pride to step on the accelerator pedal reaction

An assembly of the 376 engine, the M1 5.4 EFI system Geely pride sedan. The car diagnostic tool uneven exhaust sound of the car exhaust pipe, driving the process occasionally step on the accelerator pedal, the engine reaction (feel the speed increase is not on), and slow acceleration, the exhaust gas in the oil generation Sauvignon and irritation of the eyes, and the exhaust gas . Pick-up: First, extract the fault code, there are two fault codes to explain the mixed gas of adaptive and oxygen sensor control.
Clear fault codes, the car, the normal system, with a timing gun measure the ignition timing, earlier, the ignition timing is adjusted to within the normal range, the effect is obvious.
Read the obd2 scan tool data stream, and found the engine load is too large, the fuel injection pulse width of 1.9-2.1 ms. Measuring the intake manifold vacuum with a vacuum gun, vacuum gauge pointer swing violently around 15 inHg (under normal circumstances, should be 20-21 inHg), is significantly lower.
The suspected gas distribution system, measurement of cylinder pressure, three cylinders are about 8kgf/cm2.
Check the valve clearance, found significantly smaller, and intake valve clearance less than 0.1mm. Adjusting the inlet valve clearance to 25 mm, and an exhaust valve to 0 30mm, and then measuring the cylinder pressure to rise to 9kgf/cm2, re-start the car, rose 20inHg intake manifold vacuum, the data stream is measured in the engine load becomes 1.5-1. 6ms.
Test, driving people to reflect accelerated more powerful than ever before, "step on the accelerator pedal response is not, and just slightly larger engine noise.

Later, they encountered a few cases of a similar failure, the majority reflect accelerate the slow, check the valve clearance is too small, by adjusting the valve clearance, engine acceleration is more powerful than ever before to accelerate the slow failure phenomenon also excluded.

Summary: As the valve gap is too small, so that the intake valve with gas phase offset, causing the cylinder underinflated, the cylinder pressure is reduced, thereby affecting the speed of the combustion cylinder mixture, so that the combustion speed becomes slower, affecting the intake pipe of the vacuum pressure, intake manifold vacuum pressure and the intake air pressure sensor output signal voltage increases, the rise of the signal voltage equivalent to the obd2 software engine load is increased, so the output from the computer wider injection pulse, causing the exhaust gas is too heavy, high fuel consumption, acceleration slow series of fault phenomena, in this case, the interaction between the typical mechanical and electronic control system failure, will appear on all electronically controlled fuel injection engine intake pressure measurement into the air, and therefore have a considerable universality and typical, and the mechanic are particularly accustomed to use the handle to adjust valve clearance does not actually have a feeler gauge, it is difficult to adjust to the standard range, the carburetor engine valve clearance requirements and not very strict, slightly smaller valve clearance and there is no obvious fault phenomenon, but electronically controlled fuel obd2 connector injection engine is different, so the correct adjustment of valve clearance using feeler gauge to adjust to the attention of the majority of colleagues remind .