i know at night when it is cold with less humidity the turbo always runs better but my car hits 15-16 psi on a hot day with bad humidity than at night when it gets colder ill hit 19.....

my friend has an evo and drove next to me on the hot day and hit 19 psi while i only hit 15. ive had this problem for a while, does anyone have any ideas on my situation.

 

i wouldnt think that temp would have anything to do w/boost pressure

 

have u checked for boost leaks?
have u checked to make sure the gauge is working correctly?
are you using 93 or higher octane gas?
are your spark plugs good?

the worst thing that usually happens in heat is that your ECU will pull timing. your boost should still read the same-unless you're starting the car from cold & then hammering on it w/out letting it warm up a little...

 

its a little wierd because at temperatures below 75 it runs like every other evo , 19drops down to 15 but hot weaqther it runs horrible.

 

colder denser air def helps, most if not all turbocharged cars tend to be "slower" in heat.

 

sounds to me like you need either a reflash and/or an Aquamist water meth kit...

 

I'm not sure of whats causing the problem but I would think of it like this...(and I could be completely wrong, this is just what common sense is telling me)

Cold air is denser than warm air. On the same note, air density doesn't show a linear decrease as heat rises. So theoretically, if you get xxx amount of temperature increase for a particular turbo, starting off with higher temps will produce thinner air at the same pressure...If thats not how it works, maybe someone could chime in that knows more about it and explain?

 

Well I just back from Arizona and my car hated it, i finally hear the infamous whine of my walbro and my car was noticable slower, also at idle i made 4lbs less of vacuum than i do in San Diego. but i have a MBC so it would hit 20 over and over again but it wasn't the same feel.