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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?
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Wanted to update this thread about my engine problem.
Bought a scanner and recorded live data. Noticed abnormal upstream and downstream O2 sensor voltages and fuel trims. Diagnosis: Faulty O2 sensors. They both had over 100,000 miles on them, so I replaced both (Denso, $28 each at RockAuto.com), and the engine runs nice and smooth again, and fuel mileage is much better.
Don’t forget to chase the manifold threads, and coat the sensor threads with anti-seize lubricant.
Lesson learned: Get a scanner and learn to use it to diagnose problems. The Scannerdanner.com forum was a GREAT help in the diagnosis. Those guys are really helpful and dedicated.
Next: CV axles, oil seals, front brake pads, and rotors!
I hate my life.
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