89 f150, 5.8L, c-6, won't idel

Discussion in 'Engine & Performance' started by cctdshop, Aug 27, 2017.

  1. cctdshop

    cctdshop Junior Member

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    Aug 27, 2017
    Crescent city California
    Hello everyone,

    I have some questions. I have a 89 f150, 5.8L, C-6, with no codes and it dies when you come to a stop, idels very sporadic up and down 1300- dies. It seams to be a lot worse when it's cold, going down the road 55 miles a hours it's fine and acccelerating is fine. It's been getting worse to the point where I need to do something so I can drive it. So I did some checking and here is what I found so far:
    I have another running truck so I replaced the IAC and map sensor at different times from my 90 bronco and the IAC and map sensor work good on my bronco and both looked good, then I swapped the iac and map sensor it reacts the same way.
    I checked for vacuum leaks I did replace some vac hose but I did not find a leak, I have even for testing plugged all the vacuum lines except for the map and fuel pressure regulator and had the same issue.
    The throttle body is in good shape and clean.
    Both fuel pumps are new and The fuel pressure is 32 lbs and 40 with the fuel pressure regulator disconnected.
    I replaced the tps five months ago and it is set at .970
    The spark plugs, wires and cap are new.
    The coil was replaced four months back and has a hot spark.
    The timing is set at 10* tdc, now with the spout out it is a lot better but still has the problem but no where as bad.
    So I remember a post where someone had posted about bad wiring something about the advance wires wrapped in foil short ? But I could not find the post ?
    I'm thinking maybe wiring or a bad pcm ? Has anyone experienced this ?
    Thanks Tim

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