Honda Accord EX 1991- Motor Runs Rough

My Honda has ran well over the years but is now experiencing some problems. The car has 200K miles on it and due to the age of the car it does not have an advanced computer system but does have a basic fuel injection system.

The motor runs pretty good when cold. But when it is fully warmed up, it has a noticeable roughness/ bumpiness when driving at a constant highway speed. You can feel the significant roughness begin as soon as it gets to “normal” driving temperature.

2 weeks ago I replaced the distributor (consists of ignition coil, ignition module, and another electronic piece). Also replaced the distributor cap, rotor, and ignition wires due to the mileage on the car. Problem did not change after replacing these.

Check engine light is NOT on.

I am thinking that it may be related to a fuel mixture issue, because it runs fairly well until the motor gets to normal temp. As soon as that happens, it gets significantly rougher. Kind of like the “automatic choke” turning off on an older car with a carburetor.

When pushing the gas peddle to the floor, the engine is smooth and accelerates OK. No roughness…

What do I need to fix now???

Would this be the symptoms of an oxygen sensor gone bad?



Our daughter still has an '87 Accord she bought when she graduated high school and is STILL driving it. (Vehicles are not a priority with her husband and her)
I think the mileage is about 400k miles now.
The body looks like hell but still runs good, so you likely still have lots left in yours.

I think your problem IS a fuel/air mix at operating temp.

That said, I suspect the engine temp sensor is faulty.

If an o2 sensor was faulty, you would (should) have a CEL on and a code to read, provided the bulb is good.

What of the previous times you have posted on this problem? Did you answer any of the diagnostic questions? Did you follow any of the advice?