Has anyone else noticed that when its raining the car lacks power for one reason or another? I barely turn the A/C on, but that is what it feels like when it rains, the car looses about 25% of its power. Even when flooring it, still seems to choke.

I know its not my imagination because i drive the same route to work each day, it has been raining here for 3 days straight and the car is just not responsive to the pedal...strange, am i the only one?

Doesn't matter if you barely turn on the A/C or if it's on full blast.

The choking is probably the VSA kicking in due to wheel spin on the wet road.

yep, noticed it for first time just last week. I forgot to mention it here. Great observation & call Gosha.

I figured the humidity was so high, that it affected the quality or density of air being taken into the intake?? The airbox is pretty sealed from water, so it cannot be that. Otherwise, at very high speeds, my car is solid as a rock. The tires certainly help, but this is the best rain car I have owned yet. The loss of throttle or power I noticed was very brief, almost like a hiccup. It happened during 2 different passing maneuvers. Both times, it was raining quite moderately. My speed was around 70, increasing to a little over 80mph, when the hiccups occurred.

How did your situation evolve Gosha?

I think it's the VSA, dude. Noticed it this week too in L.A. – doesn't rain out here ever but when it does for the first time the roads get wicked oily and crap but my wheels didn't spin out once, so because of that I believe it to be the VSA.

blacklisted, were you driving on the highway at all though, without traffic too, haha?? you know what, I guess vsa does not distinguish hydroplaning from spinning out. so, the vsa could sense the wet conditions & reduce throttle power to reduce hydroplaning? I thought VSA only worked during and after an instability occurs. Is that incorrect? If so, how does VSA sense the wet conditions before any hydroplaning/or slippage/spinning occurs? Perhaps, it does occur at amounts that we cannot sense with the sound of rain & being inside the car etc.

Keep it in D3, it has more of a kick.

-GT

It's the moisture in the air. If it was VSA the indicator on the dash would flash.

ha, great point. woohoo, my first hunch was right:thmsup:, probably. :paranoid:

VSA was never kicking in, or any flashing light for that matter. I did have it turned on though.

It felt like a constant loss of power, it was not like it was kicking in and going to normal.

But you guys maybe right, its the cars sensors sensing rain and wet conditions and lowering the cars power output for it to spin less. And having wet air doesnt help much either.

yep, noticed it for first time just last week. I forgot to mention it here. Great observation & call Gosha.

I figured the humidity was so high, that it affected the quality or density of air being taken into the intake?? The airbox is pretty sealed from water, so it cannot be that. Otherwise, at very high speeds, my car is solid as a rock. The tires certainly help, but this is the best rain car I have owned yet. The loss of throttle or power I noticed was very brief, almost like a hiccup. It happened during 2 different passing maneuvers. Both times, it was raining quite moderately. My speed was around 70, increasing to a little over 80mph, when the hiccups occurred.

How did your situation evolve Gosha?

It's the moisture in the air. If it was VSA the indicator on the dash would flash.

I don't think humidity will decrease the hp to a point where you can actually feel the decrease in hp.

"Humidity differences could range from 0 percent humidity at 40 degrees F in winter, to 70 percent at 110 degrees in summer. This would result in a 4 percent change in horsepower output."
“If the humidity went from 0 to 30 percent — and all other factors remained the same — the loss of power on a 200 hp engine would be 1.4 hp. This small a change wouldn’t be noticeable to anyone except a racer tuned right on the edge.”

http://www.bwbmag.com/output.cfm?id=942751

Horsepower Calculators based on temperature, pressure, and humidity:

http://www.anycalculator.com/enginehorsepower.htm
http://www.csgnetwork.com/relhumhpcalc.html

this is the article you sent - Ever wonder why your boat seems like it runs better some days than others? Rest easy, friend. It’s not your imagination. Just as weather patterns have a direct effect on the feeding habits of fish, changes in air temperature, humidity and barometric pressure affect an engine’s performance — be it an outboard, inboard, two-stroke or four-stroke. Such weather-related performance issues stem from the fact that internal combustion engines are, essentially, air pumps — and in order to run at peak efficiency, they depend on a specific ratio of air mixed with fuel.


are we reading the same thing?? it syas exactly what i said. --- - ---- “In turn, the horsepower and torque available from a normally aspirated engine depend upon the density of that air,” says Richard Shelquist, an expert in engine mechanics and owner of Shelquist Engineering in Longmont, Colorado. “Higher air density means more oxygen molecules are available for combustion and, hence, more power. Lower air density means less oxygen and less power.”

"Run the same engine on a 100-degree day, with the barometer at 29.53 in.-Hg and the humidity a steamy 80 percent, and power is now down to 185 hp — a whopping 15 hp loss. "

rain is 100% humidity, haha.

the numbers the article quotes, as in .6mph loss/gain is for a boat on water.

this is the article you sent - Ever wonder why your boat seems like it runs better some days than others? Rest easy, friend. It’s not your imagination. Just as weather patterns have a direct effect on the feeding habits of fish, changes in air temperature, humidity and barometric pressure affect an engine’s performance — be it an outboard, inboard, two-stroke or four-stroke. Such weather-related performance issues stem from the fact that internal combustion engines are, essentially, air pumps — and in order to run at peak efficiency, they depend on a specific ratio of air mixed with fuel.


are we reading the same thing?? it syas exactly what i said. --- - ---- “In turn, the horsepower and torque available from a normally aspirated engine depend upon the density of that air,” says Richard Shelquist, an expert in engine mechanics and owner of Shelquist Engineering in Longmont, Colorado. “Higher air density means more oxygen molecules are available for combustion and, hence, more power. Lower air density means less oxygen and less power.”

"Run the same engine on a 100-degree day, with the barometer at 29.53 in.-Hg and the humidity a steamy 80 percent, and power is now down to 185 hp — a whopping 15 hp loss. "

rain is 100% humidity, haha.

the numbers the article quotes, as in .6mph loss/gain is for a boat on water.

Exactly, hp depends a whole lot more on temperature and pressure rather than humidity. Did you check out the hp calculator? At 70F and standard pressure, the difference between 0 and 100% humidity is 3%.

nope, i was satisfied with the article you found. At 90 degrees in south florida, it is certainly more than 3% then. also, every car or air pump acts differently to its environment, perhaps our cars are just quirky in humid & hot environments. If I or any of us could think of a better reason, I am all ears. But, the vsa light would flash if it was the cause. also, i am almost certain vsa only comes into play after a instability occurs, not before - that's traction control.

blacklisted, were you driving on the highway at all though, without traffic too, haha??

Maybeeee lol

nope, i was satisfied with the article you found. At 90 degrees in south florida, it is certainly more than 3% then. also, every car or air pump acts differently to its environment, perhaps our cars are just quirky in humid & hot environments. If I or any of us could think of a better reason, I am all ears. But, the vsa light would flash if it was the cause. also, i am almost certain vsa only comes into play after a instability occurs, not before - that's traction control.

Traction control is intergrated into VSA. I don't think it could be the weather since he said it was "choking" when he floored it.

In your original post you said humidity is to blame because it lowers the air density. Humidity does lower air density but it doesn't do much compared to an increase in air temperature or a decrease in pressure. Like the article stated, “if the humidity went from 0 to 30 percent — and all other factors remained the same — the loss of power on a 200 hp engine would be 1.4 hp. This small a change wouldn’t be noticeable to anyone except a racer tuned right on the edge.” Change the temperature by 30F and you will see a decrease of around 10hp. The air temperature is usually a lower when it's raining so the engine would actually gain hp due to the lower temperature even if the humidity is 100%. The reason for the lower hp during rain is because of the lower pressure which greatly influence air density.

i did not say humidity lowers air density. i said humidity affects density. which it clearly does. i know factually, that air density affects the engine more than pressure. take your car to mt. everest, see what happens. air density & water density in air are 2 separate factors. mt everest has such thin air, a car cannot perform without ice road trucker type treatments. put enuf water in the air near an engine somewhere below sea level, it will affect the car as well, if not hydrolock, ha. but, it seems you have conceded to some factor in the air causing the issue. if not humidity, then temperature. i can live with that. all i know is, there is no fix for highly dense humid air clogging up the intake whereas the ice road truckers do have fixes for the cold ice road..... anyhow, i am going to bed. you will have to continue your debate with another member my friend. Good nite all.

i did not say humidity lowers air density. i said humidity affects density. which it clearly does. i know factually, that air density affects the engine more than pressure. take your car to mt. everest, see what happens. air density & water density in air are 2 separate factors. mt everest has such thin air, a car cannot perform without ice road trucker type treatments. put enuf water in the air near an engine somewhere below sea level, it will affect the car as well, if not hydrolock, ha. but, it seems you have conceded to some factor in the air causing the issue. if not humidity, then temperature. i can live with that. all i know is, there is no fix for highly dense humid air clogging up the intake whereas the ice road truckers do have fixes for the cold ice road..... anyhow, i am going to bed. you will have to continue your debate with another member my friend. Good nite all.

The air density is lower on Mt. Everest because the pressure there is lower so pressure affects air density. Air density and water density are inversely related. I'm simply correcting your original post stating that the cause of the OP's problem was due to higher humidity lowering air density. This correct but the difference in humidity is so small that you won't be able to feel it. The lower air pressure is causing the problem by lowering the air density much more than humidity ever can.