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'87 Suburban with 350. AIR/EGR hookups (rough idle, rich idle)

Discussion in 'Chevy Trucks' started by Erond, Apr 7, 2003.

  1. Erond

    Erond Junior Member
    from Oregon
    Messages: 1

    '87 Suburban 1/2-ton 4x4 with a 350 and TBI (TH700R4 tranny).

    Bought used, and over the past year I've been puttering with it trying to get everything "just right".

    I've replaced O2 sensor, EGR, and TPS per code-scanner results. I've also replaced the IAC and MAP sensor for troubleshooting.

    There's a lot of done this/done that with the truck. After replacing everything the computer was complaining about, I started getting a very rich idle (smoke, smell, and scantool shows O2 pegged). While searching for troubleshooting help, I found a picture of the same engine with the AIR/Smog hoses routed differently. One hose goes to exhaust, the other goes to the air cleaner. I reversed the hoses to match the picture and everything seemed good.

    Just recently, I've started getting a very rough idle and surging at idle after fully warmed up (15-20 minutes). I found a bad gasket on one injector (spray + globules of gas) and a gas leak on the return fuel line. I fixed those problems, and I still have the rich/surge idle.

    For grins, I swapped the smog hoses again, and I'm back to runs fine otherwise, but rich idle.

    About the only thing I haven't changed yet is the AIR diverter/bypass valve. Before I do that, I want to make sure hoses are good. The underhood sticker doesn't show routing for the smog hoses, and the EGR vacuum switch has vacuum, vent, and EGR but they aren't marked.

    My Chilton's doesn't show the details either.

    Anybody have smog/vacuum house routing for this?

    I can provide pictures of everything if needed.