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Slow idle on cold start/wants to die

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by kenakin, Nov 18, 2008.

  1. kenakin

    kenakin New Member

    2002 Chevy Silverado 1500 z71 106k miles. A little while ago my service engine soon light came on. I stopped by an auto parts store and had them hook up the code reader and they said it wasnt returning any codes. Now that the mornings are getting much colder here, when I start it first thing in the morning, it doesnt idle up like it should and falls down to about 500 rpm and every few seconds sounds like it is going to die. I can drive it for about 30 minutes and it still has the same problem but after that, it seems to do fine the rest of the day. The other day, the service engine soon light came on again and this time started flashing...which according to the manual means there was a misfire detected. Any ideas what could be causing this problem?
  2. pmf608

    pmf608 Epic Member 5+ Years 1000 Posts

    My '01 did that for a while. The bad idle and flashing light came at different times for me, but I fixed both problems. With general poor engine performance right after starting, I replaced the fuel filter. When the SES light started blinking, I replaced all of my sparkplugs (they were overdue anyway). Now I don't seem to have any problems. Hope this helped.
  3. kenakin

    kenakin New Member

    Thanks for the reply. I have thought about changing both of those. I just cant figure out why, if its either a fuel filter or plug, that it just has this problem on cold startup and then seems to do fine after running for 30 minutes or more.
  4. Springthing

    Springthing Epic Member 5+ Years 1000 Posts

    Kenakin-

    I had this problem with another vehicle some time ago. This was during cold or generally bad weather mornings. The car would start.. putter..and then putter out dead. It would keep this up until I was on the road and at normal operating temperatures for a little while.

    After a time of looking around and gathering information I changed out the plugs and wires. It ran fine afterwards! The only explanation I could find was that I had a bad wire somewhere and that the cold and crappy mornings had put condensation and/or frost on the wire. Once they were totally dry or maybe just warmed up they worked fine.

    I'm not sure if this helps at all but you never know!
  5. sdavis2702

    sdavis2702 Rockstar 100 Posts

    Eh... I found this thread through the search feature and I am having the same exact problem in my new (new to me) Silverado. I felt like it was either my plugs, fuel delivery, or both. Looks like my thoughts may have been correct.
  6. kenakin

    kenakin New Member

    Update

    Since my original post I have changed plugs and wires, pcv valve, and fuel filter. Still same problem. Any more ideas? MAF sensor??
  7. dubya4472

    dubya4472 New Member

    I drive a 2002 Silverado Z71 w/ 5.3L V8. I had the same problem (rough idle on cold mornings, engine died until it warmed up, engine light flashing). I had the codes ran and mine read that my MAP sensor was failing, so I took it by the mechanic and had it replaced today. The light is off and it hasn't come back on yet, knock wood.

    Have them check your MAP sensor.

    Auto Zone can hook up their computer and tell you where the misfire is coming from. Takes them about 60 seconds and it doesn't cost a thing. Let us know what you find out.
  8. eyegore

    eyegore Rockstar 100 Posts

    Just a thought. Stop by the dealer to see if there is any updates for the computer. Did so with some problems I had with my '07 Silverado. Got 2 updates and a big notice on better performance.
  9. kenakin

    kenakin New Member

    Replaced fuel pump and all symptoms are gone. Craziest thing Ive ever seen. Dont know why the fuel pump going bad would cause those symptoms during cold temps only.
  10. kenakin

    kenakin New Member

    Well, I thought that fixed it but the next day it was doing the same thing as stated in my original post. Yesterday I unplugged the MAF sensor and it ran fine. So I think I've found my culprit.

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