Stop light idle is rough, OK when driving

Discussion in 'Engine & Performance' started by scoopyg, Mar 18, 2018.

  1. scoopyg

    scoopyg Junior Member

    Posts:
    3
    Likes Received:
    0
    Joined:
    Mar 18, 2018
    Location:
    florida
    Hello Ford F-150 folks,

    My 2003 with 4.6 engine is acting weird. It will go down the highway just fine, but when I'm at low idle, it heaves and sputters like it's going to stall. I've researched this condition on the web, and I was convinced it was the VCT Solenoid. But it seems that the VCT didn't come about until 2004.

    My check engine light is on, and the boys at Auto Zone ran the diagnostic on it. They say it's the PVC valve, but they sold me a push-in valve, and mine "screws" in. So now with the new correct PVC valve, there is no improvement. Any ideas?

    Thanks from Tampa, Rich
     
  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

    Age:
    53
    Posts:
    9,387
    Likes Received:
    491
    Joined:
    Nov 28, 2010
    Location:
    Ringgold, Georgia
    Welcome aboard scoopyg.

    How is it on idling at start up ?
    Is it rough then also or smooth ?

    Sent from my SM-G930P using Tapatalk
     
  3. scoopyg

    scoopyg Junior Member

    Posts:
    3
    Likes Received:
    0
    Joined:
    Mar 18, 2018
    Location:
    florida
    Thanks Roush, the truck starts up just fine, and idles well at startup. I have noticed that the start idle seems significantly higher than usual.
     
  4. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

    Age:
    53
    Posts:
    9,387
    Likes Received:
    491
    Joined:
    Nov 28, 2010
    Location:
    Ringgold, Georgia
    Of course it's not giving you a
    check engine light to read any codes.
    I was going to say vacuum leak or IAC valve but not sure with those symptoms.


    Sent from my SM-G930P using Tapatalk
     
  5. ak_cowboy

    ak_cowboy Penguin Hunter

    Age:
    31
    Posts:
    14,690
    Likes Received:
    239
    Joined:
    Nov 28, 2010
    Location:
    Alaska
    When was the last time you changed the sparkplugs or coils?
     
  6. Pity7700

    Pity7700 oh umm...uhh?

    Age:
    28
    Posts:
    7,894
    Likes Received:
    277
    Joined:
    Nov 28, 2010
    Location:
    Flat rock Michigan
    I would search for a broken hose/vac line. I had a similar issue on my 02 F150. Horrible idle but ran fine when I was on the gas. Turned out to be a split elbow, replaced and problem solved. The hoses and elbows get so brittle and deteriorate.
     

Share This Page