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BMW engine rotate speed does not stabilize corrective maintenance
From;    Author:Stand originally

Breakdown phenomenon: 316 cars carry a BMW 164E1 engine. Sometimes no matter cold car heats up a car, fast meeting is in idle 1200, beat between 1500r / Min; Enter block or the idle when opening air conditioning fast in 1500, beat between 1800r / Min, sometimes very flabby calm.

Corrective maintenance:

1. Check air flowmeter: Measure 1 # to have 5V voltage, and it is normal that 5 # foot and engine computer take iron jointly; Measure its 1 # and resistor is 500 ohm between foot and 3 # foot, resistor is 1360 ohm between 2 # foot and 3 # foot; Measure value of voltage of line of 2 # foot, 1200, when 1500r / Min 2. 33, 2. 47V, voltage follows the change of rotate speed and change accordingly, when quickening 2500r / Min, voltage is 2. 7V, all normal.

2. Measure the resistance between the foot of the 4th # of air flowmeter and foot of the 5th # , check temperature sensor resistance, 2300 ohm are when 20 ℃ , 970 ohm are when 50 ℃ .

3. Survey engine computer 12 # foot and the resistance between 43 # feet, check resistance of sensor of solar term position, idle fast when for 1050 ohm, 4320 ohm are when full load, measure its voltage to be worth in a standard-sized sheet, when closing completely, be 1. 25, 4. 98V, without interrupt a phenomenon, it is normal to all be.

4. Measure idle fast control a powerful person is undee, when Min of / of 800r of normal rotate speed, about the weaveform after 2s is normal square wave, be in 1200, when 1500r / Min, one is formed in 12V place linear. Test idle condition of movement of fast control a powerful person all normal, resistance is 8 ± normally for 100(2 ohmic) .

5. Detect oxygen sensor, its voltage is in 0. 4, 0. Between 45V, change is very little, value of the voltage after quickening 2500r / Min is 0. 55, 0. 58V, with normal change the value nots agree with. Oxygen sensor creates the job because of ageing undesirable, change after the sensor that contain oxygen, trouble removal.