Air temperature

[Zviator]

I notice that on a warm day (i'm in socal BTW), my 93 5sfe auto starts and runs smoothly, very tiny of vibration that u can feel (with our without AC).

However, on a typical cool day, I can actually feel a bit of jerky, even after a hour of driving. FYI, no overheat, no major symtoms ...

Just wondering if it's just me, or the outside temperature that affect the engine and tranny running. I dont really have a problem with the car right now, but it's just good to know.

Thanks,

P.S.: One thing need to mention, I learn in college phyics that the higher the temperature the engine can operate in, the better the efficency. If that's the case then why ta hell do we need cool air intake ???

[JCamry94]

Originally Posted by Camricer

I notice that on a warm day (i'm in socal BTW), my 93 5sfe auto starts and runs smoothly, very tiny of vibration that u can feel (with our without AC).

However, on a typical cool day, I can actually feel a bit of jerky, even after a hour of driving. FYI, no overheat, no major symtoms ...

Just wondering if it's just me, or the outside temperature that affect the engine and tranny running. I dont really have a problem with the car right now, but it's just good to know.

Thanks,

P.S.: One thing need to mention, I learn in college phyics that the higher the temperature the engine can operate in, the better the efficency. If that's the case then why ta hell do we need cool air intake ???

The higher the temp that the engine can operate in would mean that it is capable of running in such a high temp... so you mean to say the most withstanding engine would be the most efficient?

The colder air that is sent into the combustion chamber, the greater everything flows, the faster, and the more efficient.

Also the amount of air inducted or forced in, will further these prior factors significantly. IE: Turbochargers.

[Mike Gerber]

Colder air is more dense; therefore you can get more air in to the same space in the cylinders. A turbocharger or a supercharger is used to force more air into the cylinders. This is referred to as "forced induction." Some forced induction engines also have intercoolers, based on the same principle of colder air being more dense. If you cool the air (forced induction or not) it shrinks just a bit, so you can force more air (actually more oxygen) in to the cylinders. You will need a bit more fuel to compensate for this increase in air, but that's a whole different discussion. When they speak of efficiency, they are usually referring to fuel efficiency. To enhance fuel efficiency, you are trying to get the engine to run on the least amount of fuel possible. When the engine is cold, it requires a bit more fuel in the air/fuel mixture to run smoothly. You have sensors to accomplish this. They give input to the car's computer based on engine (actually coolant) temperature and incoming air temperature. The car's computer adjusts the fuel mixture accordingly. The sooner the car reaches normal operating temperature, the more fuel efficient it runs.

As far as your problem, I would check for engine trouble codes. If no codes are present, I would inspect or change ignition system components (spark plugs, spark plug wires, distributor cap, distributor rotor and coil). You don't mention how many miles the engine has on it or what maintenance has been done, but engine trouble codes and ignition system components are the most common suspects when you have a cold drivability problem.

Mike

[cruisn76]

Originally Posted by Camricer

I notice that on a warm day (i'm in socal BTW), my 93 5sfe auto starts and runs smoothly, very tiny of vibration that u can feel (with our without AC).

However, on a typical cool day, I can actually feel a bit of jerky, even after a hour of driving. FYI, no overheat, no major symtoms ...

Just wondering if it's just me, or the outside temperature that affect the engine and tranny running. I dont really have a problem with the car right now, but it's just good to know.

Thanks,

P.S.: One thing need to mention, I learn in college phyics that the higher the temperature the engine can operate in, the better the efficency. If that's the case then why ta hell do we need cool air intake ???

I know what you mean. When the temperature gets colder and colder, the engine idle gets rougher and rougher. I have the same issue. I think this is what the OP means, not turbo chargers and stuff.

[Zviator]

Originally Posted by JCamry94

The higher the temp that the engine can operate in would mean that it is capable of running in such a high temp... so you mean to say the most withstanding engine would be the most efficient?

That was one of the law in thermodynamics http://galileo.phys.virginia.edu/cla...LawsThermo.pdf

Technically, every engine has a limit on efficency that it can reach, in order to extend the limit (better efficency), you got 2 options, one of them is raising the operational temperature of the engine. Correct me if i'm wrong though.

[Zviator]

Originally Posted by Mike Gerber

As far as your problem, I would check for engine trouble codes. If no codes are present, I would inspect or change ignition system components (spark plugs, spark plug wires, distributor cap, distributor rotor and coil). You don't mention how many miles the engine has on it or what maintenance has been done, but engine trouble codes and ignition system components are the most common suspects when you have a cold drivability problem.

Mike

Thanks men, my 5sfe reached 200k last month, I did all the maintance two times more and two times sooner than what's recommended on the mannual I dont really have a problem with it right now, but it's good to know.

[Zviator]

Originally Posted by cruisn76

I know what you mean. When the temperature gets colder and colder, the engine idle gets rougher and rougher. I have the same issue. I think this is what the OP means, not turbo chargers and stuff.

Baller men, so I was wondering how did you guys in the north handle the cam during the snowy winter.

[cruisn76]

^ During the winter when it is -40 degrees (with windchill) you can feel the car struggle to start because it is so cold. So far my cam has survived through two winters, this winter I might be a bit worried, since my starter right now is acting weird. Some days it would start on the first click, some days on the third (never exceeded three tries) a bit odd. Even my 89 accord back in the day would start no problems at that thing was at almost 400k miles, and it was a carburetor