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Old 06-23-2009, 11:58 AM   #1
Jrags87
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Default Low boost /w warmer weather

Quick question .. past few days its been about 75 - 85 degrees out

max boost in 4th will hit anywhere from 16 - 17 psi according to accessport

its tuned for cobb stage 2 @ 17.5

i've already tried an ecu reset

does weather really have that much effect on max boost? or could there be other issues like leaks.

thanks
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Old 06-23-2009, 12:06 PM   #2
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Are you using the AP as your engine management? I'm not really sure how flexible it is on the boost maps (i.e. does it pull boost when it's hot and humid to help save the engine), but my 03 tapered back boost on really hot days when it was in stock form. I guess what I'm saying is that your results don't seem odd to me.
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Old 06-23-2009, 12:07 PM   #3
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seems normal, i boost slightly higher when it is cold out
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Old 06-23-2009, 12:07 PM   #4
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That's pretty much how it is for most of us.
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Old 06-23-2009, 12:08 PM   #5
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Is the loss consistent, or is it only happening during warm weather?

Hoses and tubes can become much more flexible during high heat and could possibly form a leak.

The access port is using an off the shelf map, correct? You individual mods could result in a pressure drop.
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Old 06-23-2009, 12:12 PM   #6
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Quote:
Originally Posted by bcware View Post
Is the loss consistent, or is it only happening during warm weather?

Hoses and tubes can become much more flexible during high heat and could possibly form a leak.

The access port is using an off the shelf map, correct? You individual mods could result in a pressure drop.
when it was colder i would boost on target .. maybe slightly higher

i guess my question should be does the ecu pull boost because of higher temp

btw mods are pretty standard stuff .. cobb downpipe .. catback exhaust .. stock airbox
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Old 06-23-2009, 01:39 PM   #7
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Quote:
i guess my question should be does the ecu pull boost because of higher temp

btw mods are pretty standard stuff .. cobb downpipe .. catback exhaust .. stock airbox
I would guess it would pull the timing and boost for safety reasons.
My car would not hit its target boost, and respond kind of slugglish when hot so does my last car, the evo. But as the tempt changes, it makes adjustments by itself.
On a hot day,on a long trip, I always pull over at a rest stop for some coffee to let my car cool alittle bit.
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Old 06-23-2009, 02:03 PM   #8
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It wont hit as high as boost when its hotter compared to colder air. Cold air is more dense than warm air.So not as much air is going in a short explanation.
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Old 06-23-2009, 02:10 PM   #9
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Quote:
Originally Posted by corms333 View Post
It wont hit as high as boost when its hotter compared to colder air. Cold air is more dense than warm air.So not as much air is going in a short explanation.
This. It doesn't pull boost. Normal.
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Old 06-23-2009, 02:44 PM   #10
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very normal
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Old 06-23-2009, 03:00 PM   #11
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Gas expands with heat, which should increase pressure. Is the ECU pulling back boost to combat expansion from heat?
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Old 06-23-2009, 04:27 PM   #12
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Quote:
Originally Posted by william_c View Post
Gas expands with heat, which should increase pressure. Is the ECU pulling back boost to combat expansion from heat?
No. Read above.
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Old 06-23-2009, 05:26 PM   #13
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Has nothing to do with the gas expansion. It has to do with the air temp as well as altitude. Both affect how dense the air is. If you live at see level and drive to a mountain with a much higher altitude. It would be PROBABLY be about the same as what your seeing now.
Hot temps = less air
Cold temps = more air
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Old 06-23-2009, 05:42 PM   #14
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you guys do realize there are correctional values in your maps based on intake temps right? Ie wastegate Correctional value (IAT) when reading 212 correct WG by 32% and such.... the ECU knows when its getting hot and how to correct to save you.
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Old 06-23-2009, 05:45 PM   #15
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^^To save your car from blowing up? Not correct your map so it hits the max boost your map is set too.
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Old 06-23-2009, 05:49 PM   #16
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Originally Posted by corms333 View Post
It wont hit as high as boost when its hotter compared to colder air. Cold air is more dense than warm air.So not as much air is going in a short explanation.
And isn't this the whole reason we have intercoolers? To cool down air for better density/more power. My car always feels peppier in the winter vs summer. Hot days are nature's heat soak.
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Old 06-23-2009, 05:52 PM   #17
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^^ yeah but its alot easier to get that cold air cold than it is summer air to the same density of a cold day.
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Old 06-23-2009, 05:56 PM   #18
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well obviously. It's getting up to about 100deg today here - not saying any intercooler will make it like a -20 day in february
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Old 06-23-2009, 05:58 PM   #19
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Exactly intercoolers can only do so much man.
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Old 06-23-2009, 10:06 PM   #20
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Quote:
Originally Posted by william_c View Post
Gas expands with heat, which should increase pressure. Is the ECU pulling back boost to combat expansion from heat?

Uhh, no. That's not how boost works. Please make sure you know what you're talking about before giving advice
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Old 06-24-2009, 07:27 AM   #21
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Nothing unusual here...
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Old 06-24-2009, 10:38 AM   #22
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Quote:
Originally Posted by Deserted1 View Post
you guys do realize there are correctional values in your maps based on intake temps right? Ie wastegate Correctional value (IAT) when reading 212 correct WG by 32% and such.... the ECU knows when its getting hot and how to correct to save you.
^^^ THIS. There are quite a few tables in the ECU that account for both air temperature (IAT) as well as altitude (and other factors). Your ECU will use these tables to adjust timing, fueling, and WGDC (amongst other parameters) based on air temp, coolant temp, altitude, knock, etc. etc. If you use ECUflash/romraider, you can see exactly what these tables do and adjust them, as necessary.

Ignore the majority of everything else posted in this thread. Gotta' love nasioc and all of the internet experts
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Old 06-24-2009, 10:49 AM   #23
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Quote:
Originally Posted by corms333 View Post
It wont hit as high as boost when its hotter compared to colder air. Cold air is more dense than warm air.So not as much air is going in a short explanation.
Agreed. With less air density, the smallish stock turbo is becoming less efficient (READ: More hair drier).


As far as the post above, heat shouldn't be the entire equation... In addition, it should take a bit more heat than 75-85 ambient temps to cause it to limit boost. Spray your intercooler before your next run.... I would definitely knock being bigger deciding factor timing and such being pulled.

Last edited by yamahaSHO; 06-24-2009 at 11:02 AM.
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Old 06-24-2009, 11:10 AM   #24
Jrags87
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Quote:
Originally Posted by yamahaSHO View Post
Agreed. With less air density, the smallish stock turbo is becoming less efficient (READ: More hair drier).


As far as the post above, heat shouldn't be the entire equation... In addition, it should take a bit more heat than 75-85 ambient temps to cause it to limit boost. Spray your intercooler before your next run.... I would definitely knock being bigger deciding factor timing and such being pulled.
i did another run and at the time noticed my intercooler spray nozzle was clogged up .. so it wasn't spraying any water and was running with an extremely heatsoaked intercooler

i fixed it and the boost climbed a little bit, making me think its pulling because of the ambient temp
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Old 06-24-2009, 11:46 AM   #25
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It's definitely the heat, however, I'm willing to bet it's that combined with a small turbo that is giving you the lower boost and tapering off sooner.
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