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Hum Before The Start-up


VAVolvo

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Ever since I got my ST chip, I turn my ignition to II and hear a hum coming from the engine like something is winding up. The car starts fine, but this morning, I turned the key to start it up and nothing happened, like there was no connection. On the third try, it started fine.

My theory is that it is a warm-up thing, because it was colder than usual this morning so I couldn't just crank it up. The car was waiting to "wind up" before it would allow me to start it. I hope this is the case.

Thanks for any info!

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Every time I start my car in the morning I get a hum too. I think the hum comes from the secondary air system that helps heat up the exhuast gases and exhuast manifold? Since my car is a California car it has every emissions gaget hooked up to it to reduce emissions, and I believe the secondary air system is part of this emissions control measure.

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Every time I start my car in the morning I get a hum too.  I think the hum comes from the secondary air system that helps heat up the exhuast gases and exhuast manifold?  Since my car is a California car it has every emissions gaget hooked up to it to reduce emissions, and I believe the secondary air system is part of this emissions control measure.

The hum at II before starting is the fuel pump priming the system. Should last about 1 - 2 seconds. I know this is it because my hum has turned into a sick-cow-like grown. Impending failure....

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The hum at II before starting is the fuel pump priming the system. Should last about 1 - 2 seconds. I know this is it because my hum has turned into a sick-cow-like grown. Impending failure....

That would make sense. Thankyou for your feedback

PEACE!

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Your hum is more than likely the Idle air motor, not the air pump if you have one, the air pump only runs after the engine is started, however the Idle air motor will hum with the key in position II. Might consider cleaning it, being cold a dirty Idle air motor might begin to hang up on the gue and gunk in there.

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What you do is take the hoses off, make sure you draw a diagram so you know how the hoses go back on, and then on the end where the hoses hook up, you clean there, if you shake the cylinder you will see the valve on the inside rotate, a good carb cleaner and you will see all kinds of stuff come out.

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