Baffling Problem After Engine Warms Up (Honda)

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  • #643105
    Barry SheaBarry Shea

      1997 Honda Civic DX
      D16Y7 – 167,000 miles
      No “Check Engine” light.

      When the engine is cold, it starts right up, idles smoothly, and runs great on the highway (65-70 MPH). But, as soon as it reaches operating temperature, it starts bogging down.

      If I don’t move the accelerator pedal, the car will slow down to 40-45 MPH, then the engine will kick back in, but will run rough.

      If I slowly press on the accelerator, there will be no response for about 1/8″ to 1/4″ of movement, then the engine will kick back in, but at a higher RPM, so I’ll have to let off the gas to slow down, and the problem will repeat.

      When this problem starts, I can smell fumes seeping into the cabin. They resemble what the inside of a valve cover smells like. Kind of a mixture of oil and exhaust.

      Sometimes, at random, the engine will start running smooth again. But, the problem soon returns.

      If I get off the highway while it’s running crappy and come to a stop, the idle will be real rough, almost to the stall point, and I’ll have to give it more gas to keep it going. Sometimes the engine will suddenly start idling smoothly again, but will eventually go back to running rough.

      It has gotten so bad that the other day I drove to the store and when I came out the engine wouldn’t start. I had to sit there for an hour and let the engine cool down before I could get it started, and it ran so rough that if I let off the accelerator it would stall. I barely got it home.

      This problem first started about 5 years ago. At first it was seldom, gradually became more frequent, then was assured, and now I can’t even drive the car anymore. Although, again, when it’s cold, it starts right up and runs great.

      I’ve taken it to 3 repair shops, who said no codes showed up on the diagnostics, so they started throwing parts at it. I’ve been hosed for over $2,000 for a catalytic convertor, distributor assembly, fuel filter, air filter, spark plugs, spark plug wires, and a PCV valve. And nothing has fixed the problem.

      I need your help. It’s definitely something related to the warming of the engine. But, why and what?

    Viewing 3 replies - 16 through 18 (of 18 total)
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    • #953212
      Chris RChris R

        I’m literally having this exact same problem
        . Replaced and check your same components along with the IACV. Did you ever find the source of why it was acting dumb? Please help lol

        Doug FelchDoug Felch

          I see this thread is pretty old but I thought I would post for people who search this in the future. I was having the same issue following timing belt replacement. This was very frustrating, I tested and replaced several sensors before finding the problem. Very low rough idle and stalling after warm up. Plus extra smoke from the exhaust.

          I found the cause to be two small vacuum lines were swapped. They were the ones that run from the intake and fuel rail over to the drivers side strut tower. the stock hoses have numbers printed on them (16 and 20 ? from memory). I had these swapped at the shock tower end. with correct routing the numbers should match the hoses at the other end that leads to a couple components in front of the shock tower. They are also shown on the emissions stick on the underside of the hood.

          Good luck.

          Navid BasherNavid Basher

            Having the exact same problem !! Plz help !

          Viewing 3 replies - 16 through 18 (of 18 total)
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