i'm just curious here. i know the temperature shouldn't affect boost pressure on a tuned lnf especially on the stock bpv and turbo. but my car was running an extra 1-1.5 psi yesterday for no reason. i saw it all the way up at 23.6 (not maintained but not just a little spike) in 3rd gear and before that it had never gone over 22.2 psi in any gear. then again i got my car in the summer and have yet to drive it in cold weather, yesterday was the first day i drove it in under 40 degree temperature.

just curious if weather DOES have any effect. thanks!

 

im trifecta tuned and it always hits 22psi no matter what the weather is like

 

I'm tri tuned also and my boost is all over the place. 22 here, 24 there etc...

 

Just as the factory tune lets you have any amount of boost you need (within reason of course) to maintain your 260 HP on a TC your tune might have the same type of parameters, where they next guy's tune might be setup to never allow it to go over certain boost. Even various trifecta tunes could be different depending upon what you bought from him or asked him for.

 

yeah i'm hptuned but i understand the principle. it's just weird to me. i was just curious if maybe something on my car was going bad, or if weather plays a role or not.

 

Often you may notice lower boost pressures with Colder temperatures as the air is denser and the car needs less Pressure to maintian the same air mix. More so with a factory tune that is aiming for specific air flow vs a specific Boost level. Higher boost pressure doesnt realy make sense with colder temps though. Its possible the computer is just trying to callibrate for the temp changes and is still not dialed in. If im not mistaken the aftermarket tunes work the same way to some extent the limits and are just set higher (this might be an over simplification)? Correct me if i am wrong?

Drastic temp changes often screw with trims and in turn could make your boost fluctuate a bit while the PCM dials it in.

 

yeah i know. colder air. more oxygen. less pressure needed.

i was confused when i saw it. cause it did it more than once.

 

ya thats just it, ur car isnt tuned to a certain hp anymore like stock, its tuned to a certain psi, it shouldnt matter what the weather is like, should always it the psi ur tuned for

 

That's just not necessarily true at all. It's more likely that it is tuned to maintain a certain air to fuel ratio and it'll make as much boost as it needs to keep that ratio.

 

Dead-on response. ECM is trying to hit that magic 260 ft. lbs. (stock car).

 

yup but that's not how it is for us tuned cars anymore. i am wondering what it's trying to achieve, or if some cars are just like this.

 

I'll bet your tuner could explain it to you.

 

i dont know much about tuning, but id think the car would just adject the fuel depending on how much air is coming in, not the boost to how much fuel.

 

or both might be reasonable?

prevsrt4owner's answer is truly the best. The guy that tuned it can surely say how it was tuned.

 

already asked him lol. waiting for my damn iphone to finish restoring itself after it felt like it needed to without my consent lol

 

I'm hptuned and see the same thing. In the mornings right now, when it's about 48 degrees, I get up to 23lbs of boost. I normally run 21.

 

Maybe Vince does it differently. I guess u could do it either way. Whatever is easiest for the tune that's run

 

I've noticed that earlier Trifecta tunes I've dealt with can change the boost a bit, but the newer ones peg at the same spot every time. I think he changed strategies at some point. I like his newer approach, as several years ago I basically overboosted on a few occasions during long runs for some reason.

 

dude exact same thing!!

all i know is i got 3 CEL's today. lol good stuff

 

It's possible that the ECU hasn't adjusted yet then, aiming for 21psi, but getting more due to the increased air density that day from the cold temps. Even learn-down takes a few key cycles going from memory. Even though the effect of learn-down is taken away with a tune, the way the ECU operates and adjusts to variables is still the same no matter what.

 

my car will run from 15 to 20 to 24psi in 1-3 (sometimes 24psi all the time) when its 75 or hotter but when its 74 or colder out side it usually runs 24psi most of the time maybe i have a boost leak or something dnt no

on a side note
when i NLS it will go from 24psi down to 20psi then back up to 24psi

 

Mine appears to have ~15psi summertime and 12-13 winter. LOL!! I'm stock though.

 

That's about right!

 

its goin to bounce around a lil with colder temps the air is denser, i would figure it would read less boost since it doesnt need to produce as muuch boost to hit target hp goal, just my thoughts i may have explained it a lil off though.