If your engine is cold, the power steering fluid is much thicker than when it is warm. The power steering pump has to work quite a bit harder too move the thicker fluid. 4 cylinder engines don't make a hell of a lot of torque a idle, therefore any extra temporary loading will cause the idle to drop until the loading is dropped or the IACV compensates for the additionalengine load.

 

In otherwords in english that means that, when your sitting at idle, your motor needs to strugle to push all your accesories. Although, I don't think your power steering fluid really thins out that much. In any case, your car really doesn't have as much power to run your alternator, so all the parasitic drag off your power steering, basically steels all the belt speed used to push your alternator, therefor, your not getting as much power to run your motor, it's almost like running on an almost dead battery.

And actually on a side note, even once your car is warm, turning the wheel while standing still will affect your idle, but generaly in the opposite way, your IAC will bump your idle up a couple hundred to compensate for the extra load. This same thing will happen if you pump your brakes a couple times while sitting still as well.

Later......

 

Actually, pumping your brake pedal several times causes a drop in intake manifold vaccum. That causes the fuel injection to compensate for momentary low engine vaccum, thus raising idle speed.

 

thank you everyone, that was very informative...now i know why when i raced on a cold motor i lost to an si (we've all done stupid things before...right? :lol: )

 

Sounds like an interesting theory........why???

 

Power assisted brakes require engine vaccum which is stored in the brake booster. Eveverytime you step on the brakes, you cause a drop in engine vaccum utilized by the brake booster.

 

Kool, never knew that

Thanx....

 

I never thought about that occurance being emissions related. My friend had a 95 Mustang 5.0GT and his car would hang between shifts (the revs wouldn't drop off) and this was to burn off emissions between shifts. This has turned out to be a very informative thread! Thanks everyone.