But think about it carefully, the main reason for poor idle speed is improper mixture ratio (that is, abnormal air-fuel ratio). If the mixture is too lean/rich, the idle speed will be unstable.
Jitter: shaking caused by unstable work.
Stroke: The rotating speed fluctuates up and down within a certain range.
Surge: the cold car is normal, and the hot car shakes intermittently.
How should we deal with these different symptoms?
Specific manifestations of poor idle speed:
A. excessive idle speed
If the vehicle breaks down:
After general throttle cleaning, if the throttle does not match or fails to match, the idle speed of the vehicle will be too high. At this time, you can manually match (power off, etc.). ).) or through diagnostic equipment.
If the vehicle breaks down:
1. When the brake pedal is depressed, the idle speed drops obviously, indicating that the excessive idle speed is caused by air leakage of the brake vacuum booster pump.
2. When the vehicle is driving at high speed, the idle speed is too high when waiting for the traffic lights, indicating that the air leakage between the engine cylinders is serious and the idle speed is too high.
3. When the engine load increases (turn on the air conditioner, turn on the steering wheel, etc. ), high idle speed returns to normal. At this time, it is mostly caused by the failure of air flow meter and air leakage at the front/rear end of throttle body.
B. Low idle speed
The main feature is that it is easy to stall when starting/shifting. Possible reasons for low idle speed are:
1. The air intake system is not smooth and blocked.
2. Poor idle speed control (such as abnormal idle switch signal and abnormal idle motor). ).
3. Fuel injector fault (dripping or blocking, line fault light).
4. pervert 4. EGR system (valve body failure, hose leakage, etc.). ).).
C. idle jitter:
Leakage and jitter resistance are circuit faults. That is, poor line contact (throttle position related lines, etc.). ).) lead to a certain high resistance, leading to engine slippage; Circuit leakage (ignition coil leakage, etc.). ).) Causes the engine to shake.
Thickness jitter, which is an oil circuit fault. That is to say, when the mixture is rich, it will cause driving, and when the mixture is thin, the engine will shake. But it should be distinguished from the cause.
Excessive carbon deposition causes idling jitter, which is manifested in the difficulty of starting the vehicle, the engine jitter after releasing the accelerator pedal, and poor acceleration at medium and high speeds.
After reading the above, I believe everyone has a further understanding of the problem of poor idle speed.
In order to better combine with practice, () Bian Xiao specially arranged a set of inspection ideas for your reference. If there are any shortcomings, please point them out.
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