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Q: My car is racing in park

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OK I have a Nissan b15 and every time I start it the engine racing in park position. what do you think is causing that...

Hey there. This is usually a sign of a vacuum leak or a faulty or dirty idle air control valve. The idle air control valve is a unit that reads the air coming into the motor as it is mixed with fuel prior to being injected into the motor. The computer uses this info to make adjustments to fueling. When this is not working properly, this may cause an imbalance in the air/fuel mixture causing a lean condition which generally will make a motor idle very high. The same effect is also true when you have an intake leak or some other vacuum leak that causes an increase in air intake relative to fuel supply. If you would like to have a precise diagnosis on this, a certified technician from YourMechanic can come to your car’s location to inspect the high idle and follow through with repairs.

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