I'm a newbie to engines and this is a general questions regarding my observations of my '93 Civic DX.
On cold days, I notice that when I start the car and drive the car sounds and feels a bit rought. The engine is louder and the clutch sounds sounds squeakier (it's about time to change the clutch btw).

On warm days, the engine is quiet and smoother. The car seems peppier too. I guess the car is old and can use some TLC.

Things like the bushings, vacuum hoses, etc. could all be refreshed along with a new clutch.

Just wondering if I'm imagining this or there is some truth to the weather dependent behavior I'm seeing...

Thanks!

 

You might have a faulty fast idle valve.

 

doesn't that valve adjust the air intake when the engine is warm? the engine rpm comes down to normal after the engine has heated up. could it still be faulty?

 

Opposite. The fast idle valve controls the idle when the engine is cold.

 

sorry that's what i meant.... when the engine is warm, the fast idle valve should close and the engine should not be reving high. so it appears to be working

 

Cold influencesa lot of things.

Thicker oil = more drag for the engine. It's working harder just to stay running. That should become normal as the engine warms up.

Cold engine = fuel doesn't vaporize as well, not as much power. That should also become normal as theengine warms up.

Does this stuff continue even after the engine's at normal operating temperature?

Does it take forever to reach normal operating temperature? If so, you may have a stuck-open thermostat.

The oil in the shock absorbers also warms up with motion. When real cold they're more stiff. That contributes to a general feeling of harshness.

 

Please disregard my responses as I misread your original post.

 

Thanks, I think everything you said is probably contributing to the sensation I get during a cold day.

My thermostat is probably stuck open... it takes forever to warm up... actually, if I'm driving at relatively high speeds, it never comes up to even a 1/3 of the way. Only when I go through stop and go traffic does the needle come up.

 

If the engine stays colder than the proper operating temperature, then the ECU gives extra gasoline because it "thinks" it needs to (based on the coolant-temperature sensor).

Get a new thermostat. Need an excuse to change anti-freeze? It loses it's anti-corrosion properties after a couple years - and you can't measure that with a float-hydrometer.

As long as we're talking about fluid lifespan, brake fluid should also be replaced every couple years too. But that's probably not part of the stuff you're complaining about in the first post.