rough idle in morning - Engine ODB2 Fault Codes


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Auto Repair Home>> Automotive Repair>> Engine ODB2 Fault Codes

jimmyd
New User

Nov 5, 2011, 3:07 PM

Post #1 of 3 (2263 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
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Nov 5, 2011, 3:40 PM

Post #2 of 3 (2239 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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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Discretesignals
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Nov 5, 2011, 4:06 PM

Post #3 of 3 (2233 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.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

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

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