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My Sierra Runs Poorly When Cold

levi2009

By levi2009
in Ask A GM Technician

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levi2009 Enthusiast

levi2009

Posted
Posted

Hi All, I've been a member since 09 and have always been able to get answers by searching, but today...no luck.

 

I have a 1999 Sierra half ton 4x4 5.3cid w/4L60E and electronic 4wd, and this is what's going on, when I start the truck it starts & idles fine, if I start driving immediately it hesitates severely on acceleration and will do so for the first 4 or 5 minutes then it will accelerate & drive fine, if I stop and shut off the engine for even 10 seconds the hesitation is back. Also if I start the engine and let it warm up for 5 minutes it accelerates fine and all is good.I have replaced the Fuel & air filters, spark plugs and cleaned the throttle body and nothing has changed.What should I check next?

Please help me out guys.

 

Thanks,Levi

 

WE LIVE IN THE LAND OF THE FREE, ONLY BECAUSE OF THE BRAVE!

Duelin Enthusiast

Duelin

Posted
Posted
Hi All, I've been a member since 09 and have always been able to get answers by searching, but today...no luck.

 

I have a 1999 Sierra half ton 4x4 5.3cid w/4L60E and electronic 4wd, and this is what's going on, when I start the truck it starts & idles fine, if I start driving immediately it hesitates severely on acceleration and will do so for the first 4 or 5 minutes then it will accelerate & drive fine, if I stop and shut off the engine for even 10 seconds the hesitation is back. Also if I start the engine and let it warm up for 5 minutes it accelerates fine and all is good.I have replaced the Fuel & air filters, spark plugs and cleaned the throttle body and nothing has changed.What should I check next?

Please help me out guys.

 

Thanks,Levi

 

WE LIVE IN THE LAND OF THE FREE, ONLY BECAUSE OF THE BRAVE!

 

I didn't know a 99 K1500 had a 5.3. The only engines that I knew were 5.0 and the 5.7.

Z45 Senior Enthusiast

Z45

Posted
Posted

Hard to say what the problem is but I had a truck once that acted this way and it turned out to be a bad 02 sensor.

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