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I've experienced this a lot recently and really noticed a trend...i'm wondering if you guys have the same thing?

during the somewhat colder parts of the year (it's easier to tell than in the summer) my car will feel twice as fast during the first 5 minutes of being warmed up than any other time. what i mean is, if i turn on the car and let it warm up a little (at least close to having the needle at half way) by doing conservative driving for several minutes, the first real acceleration is insane--my car pulls the same or more than my 540i! but it's only during that first cold/just warmed up period...it's bizarre..

and beyond that, my car is moody--it has fast and slow days....even on back to back days with nearly identical weather, my car can feel worlds faster one day than it does the other....i don't get it, is everyone's car this variable?
 

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There I was, Sicily, 1918..
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I've noticed this (the variable part) many times. Dunno what causes it, however.

I've noticed that the colder it gets, the more my enigne growls... as if I had a CAI (go figure) :)
 

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Lying, drunken cheat
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Are you sure the car is being variable...or is it you? :)
 

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i noticed this too, pretty cool.
 

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Bimmerfest Co-Founder
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Also remember that OBD 2 is adaptive. If you don't drive your car hard the ECU scales back the power. This is why you can get a dyno HP increase by resetting your ECU.

Also as people have mentioned cold air is denser and makes more power. When you first start your car the intake is going to be cold, keeping the intake air temps down.

Tim
 

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I know what you mean and it has nothing to do with the cold weather. YES on cold days my car is faster BUT there is a problem whereby performance is sporatic at times even between startups a few minutes apart.

There were days when even in 80-90 degree weather its like someone unleashed something in my engine and the car screams forward like I got 25HP kick in the @ss. Then shut the car off (like go in a store) come out and start it up and it is driving miss daisy.

There is also sporatic performance in different temps. OBVIOUSLY with cold weather there is greater performance but given that, there is sporatic performance dips in cold weather to. It is odd and I wonder if this problem only affects Steptronic transmissions?

What I know is this, when your car is cold by ODBII and EPA regulations manufacturers are allowed to run the engine rich meaning more fuel which produces more emissions. As the engine warms and the catalytic converter heats up and engine temps go up, there is less enrichment. The problem with this is that the sporatic performance is not just when the car is cold it could be from one stop light to the next. I believe the mass air sensor is receiving inaccurate temperature information as well as it is prone to heat soak. Audi used to have a similar MAF and they went back to their old metal one as they found the plastic caused sporatic results that their software wasn't built to handle.

So I think there are multiple things going on all reacting off one another screwing with adaptation.




JetBlack330xi said:
I've experienced this a lot recently and really noticed a trend...i'm wondering if you guys have the same thing?

during the somewhat colder parts of the year (it's easier to tell than in the summer) my car will feel twice as fast during the first 5 minutes of being warmed up than any other time. what i mean is, if i turn on the car and let it warm up a little (at least close to having the needle at half way) by doing conservative driving for several minutes, the first real acceleration is insane--my car pulls the same or more than my 540i! but it's only during that first cold/just warmed up period...it's bizarre..

and beyond that, my car is moody--it has fast and slow days....even on back to back days with nearly identical weather, my car can feel worlds faster one day than it does the other....i don't get it, is everyone's car this variable?
 

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me too... but my camshaft position sensor is going bad.... however, when I was up in Iowa last week... I was lovin the roar my engine had in the very cold weather.. which is gone now here in houston.....
 

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First 19" ZHP
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ya my car gets moody as well it goes fast when it feels like it and sometimes it just chills back and doesnt want to run, i need a CAI
 

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cold air does that when engine is not that hot

its the air cold air is better for a engine better than hot air. put
in the mix a engine that is not hot and that gives you top performance. that is why if you go to a drag strip track they
say between 1/4 mile runs to kool off your engine. if you keep runing your car it will go slower. kooler engines are better in 1/4 mile runs.
bobm3 :thumbup: :thumbup:
 
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