Starting GMC when cold..... hard start?

H

healthnut

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I have a 1999 GMC Sierra 1500 pickup. When it gets to about 30 degrees and cloder it starts at a high RPM and goes to about 500 RPM. It also gives a slight knocking sound untill it warms up. Anyone knows if this is a probem?
"It also gives a slight knocking sound untill it warms up"
Im using 5-30 in summer and 10-30 in winter
 
The high rpm is normal for a cold start, its meant to warm up the engine to a normal operating condition. Then once the computer see's this it adjust your idle air control valve to bring down your idle speed. The knocking could be several things... need more info. Does it do it all the time even when the car is warm or during the summer? You have to be specific here.
 
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