hot day = less power. whats wrong?

[Giodog2000]

Hi all , Hope someone can help me on this one ....On cold days (like today ) car runs great . But on warmer days like we had this week (25C) my car has a serious lack of power. I also noticed the fan is always on and never seams to stop even if I'm on highway . I tried with no air conditionning btw. Does the fan on your car stop after a few min or does it stay on all the time ? What could cause my 323 to be so slughish in warm weather? Thanks !

[BMW4EVER]

I guess you have a open intake system right?
well, in theory, when hot, the oxygen molecules are more appart from each other; which lowers the air density... so less oxygen. When less oxygen, equals less air to make power, therefore less power.

the other thing might be... when hot, enverything in the engine is hot. So there will be less compressiong and less power.

I also feel more power when it rains, so I beleive there is something to do with the air humidity.

hope it helps.

[Lee]

Breathing cold(er) air is the key to performance. Your motor needs oxygen, as it has been mentionned, hot air has the O2 molecules spread apart. It is not as dense. Also, trhe DME senses hot air and leans out the fuel mixture. Not good either. As I usually say, the original airbox is a much better idea than a cone breathing warm air. Install the original airbox back please.

[Giodog2000]

Breathing cold(er) air is the key to performance. Your motor needs oxygen, as it has been mentionned, hot air has the O2 molecules spread apart. It is not as dense. Also, trhe DME senses hot air and leans out the fuel mixture. Not good either. As I usually say, the original airbox is a much better idea than a cone breathing warm air. Install the original airbox back please.


The original airbox is on the car . When I bought the car , the cone was on and I took that out to put the original box in. Could it be some kinda sensor problem? I can understand the hot air theory but isn't there a sensor that does exactly that to take the temp. and ajust mixture ?

Thanks for all your help guys.

[Lee]

Make sure that all sensors are properly connected.When was last time the car was tuned by a properly equipped shop with diagnostic equipment?

[Nano]

you also may have contaminated coolant are a defective thermostat.

cooant needs to be flushed once in a while, if coolant fluids is old it may be contaminated or altered and may corrode, clog or degrade coolant system components.

[Giodog2000]

I'LL start by that ....flush coolant and thrmostat (shouldn't cost that much) then if didn't fix problem I'll have diagnostic done like Lee said. Does that sound a good choice? Oh also, does anyone know Garage Denis Boisclair in St-Sulpice? Is he any good?