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rough idle in morning


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jimmyd
New User

Nov 5, 2011, 3:07 PM

Post #1 of 3 (2405 views)
rough idle in morning Sign In

I have2003 chevy silverado, 1500,0 5.3, 95,000 miles. #1 issue is in the mornings now that it's colder it starts fine but idles very rough, sounds like it wants to die. After it warms it's fine all day. Check engine light came on and was read to have error codes P0171 and P0174. Could it be MAF sensor causing morning problem? I had fuel pump replaced last month that took care of some performance issues and hard starts i was experiencing.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 5, 2011, 3:40 PM

Post #2 of 3 (2381 views)
Re: rough idle in morning Sign In

You have a lean condition. There are dozens of ways for that to happen. You need to start looking for air or vacuum leaks first.



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Discretesignals
Ultimate Carjunky / Moderator
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Nov 5, 2011, 4:06 PM

Post #3 of 3 (2375 views)
Re: rough idle in morning Sign In

Need to look at the freeze frame data to see when the lean codes set.

Some of these problems are hard to diagnose without some data stream information as the problem is occurring. You can also monitor misfire counts to see if it is missing in any particular cylinder, but you need an enhanced scan tool. What is the fuel pressure when the engine is running rough? Just cause you replace the pump doesn't mean you couldn't still have a fuel delivery issue.





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(This post was edited by Discretesignals on Nov 5, 2011, 4:07 PM)






 
 
 






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