boost in cold weather

[Blue_S4]

normally my car spikes 15 holds 13-14 to red. lately we have had some cold temps (below 20 F) and i notice the car wont boost over 10. is that normal in cold weather? I assume the MAF is just measuring the density of air as being that much greater in cold weather and the N75 limiting it? is my thinking correct or is something wrong? anyone else see this?

[mholme]

Nice cool, dense air makes forced induction cars run stronger.

[Blue_S4]

well yea, but thats after the MAF. what about before if its too dense before wouldnt it limit how much it is requesting for boost because its just measureing a volume of air normally isnt it. cooler air helps later for sure.

and its for sure not as strong right now.

[gointoscott]

Its been below 20 degree's here too and my car boosts normal - right around 15psi.

usually if it wont go over 10 it could be in limp mode.

I would check for codes. If EGT's are throwing codes it wont boost over 10

Also the obvious thing would be check for leaks too.

[mholme]

Oh ok, I think I see what you're saying. But that the cooler temps allow the MAF to adjust the mixture to allow for more fuel as it's seeing the dense air, so it starts with the MAF regardless..if I'm understanding you correctly.

[Blue_S4]

yes. hmm. something is wrong im going to guess. stupid car...time to fix something else again.........

brand new EGTs, so shouldnt be a problem there, but there is no limp at 10psi, limp is 5, so maybe i have a small leak. stupid cold weather. stupid michigan. maybe i should do the LSx swap to just for reliability and sound. geez.

who wants to buy a APB block with K04s and supporting goodies?

[gointoscott]

Yes that is right. Limp is 5ish psi. Sorry about that, didnt mean to lead you astray.

Do you have vag-com? I would try logging block 115 to see what actual boost and requested boost is showing. Can help to see if there is a leak.

[mholme]

Something may or may not be wrong though. If you're romping on the throttle in cold, you may be hitting the requested boost limit based on the ECU readings earlier than usual because of the dense air. So then, I think your theory would be correct.

[Blue_S4]

i hope so. i mean i rarely get to get on it, because there is snow everywhere but roads have been dry last few days so been enjoying it. i only have the ebay cable to check codes i really need to just buy the real deal. i need it.

[mholme]

Yeah, the real deal is needed for anything beyond the basics, like this, but hopefully that's all it is. I don't get cold weather boost limit, but others do experience it.

[Blue_S4]

good. i hope thats all it is. going stage 3 killed me in oct. still recovering!

[Trigger Happy]

good. i hope thats all it is. going stage 3 killed me in oct. still recovering!

Check for codes and log as previous members have said. Your car may boost a psi or 2 less due to the cold air but 5 seems like alot. Does it feel slower than normal? If it does its most likely a boost leak.

[Mantis]

I would do a pressure test just to be safe on this one. It gets really cold here, and I dont notice a drop in boost, it actually boosts harder. I get the tiniest spike, then holds at 22psi till 6500

[jameskkk3]

when its cold out my car seems to spike a pound more

[Mantis]

Agreed, I see a 1-2 psi increase in spike, it immediately settles down to normal. I attribute this to the N75 not being able to react as quickly to the MAF when the air is very dense, or vice versa

[00s4slvr]

actually when its colder my car seems to spike a pound less and hold less cause im assuming since its colder it doesnt need as much psi to make the same power. at least someone on here told me that!

[imola]

Mine spikes at around the usual and it was -27*F the other night..

[2mMy]

mine spikes higher in -10C. Usually a little over 18psi, but the highest spike so far is 20,5psi :)

[s4andtls]

Mine spikes at around the usual and it was -27*F the other night..

-27F, stage 3, that has got to be like 50 more hp than at 70F !!!!!!!!

[VonPooper]

man..i used to have family in fargo...those xmas trips were brutal.

[Blue_S4]

could bad gas be causing this? i have plugs that need to be changed but would the ECU request less boost if the cheap plugs were cause random misfires?

[bs6x]

could bad gas be causing this? i have plugs that need to be changed but would the ECU request less boost if the cheap plugs were cause random misfires?

What software are you running? I am having a similar problem. I miss like crazy at idle in cold temp lately. Keeps throwing a cell.

[Mantis]

Have you done a boost leak/pressure test yet?

[00s4slvr]

bad gas could certainly cause the boost issue or possibly a small leak

[Blue_S4]

Cuz it's better now. So who knows

[S4NORICE]

yeah, when it gets in the low teens, i see my boost drop off about 2psi. I also see my gas milage go down a bit, nothing substantial tho... APR software here, no leaks - I'm 99.9% sure of it. I have new EGT's as well..

[S4NORICE]

mine spikes higher in -10C. Usually a little over 18psi, but the highest spike so far is 20,5psi :)

-10C holy crap batman! I thought upstate NY sucked, but Thats farken COLD!

[Rated S]

Mine spikes at around the usual and it was -27*F the other night..

Jesus Christ, how do you people live in not-constant 72*F weather?

[imola]

Jesus Christ, how do you people live in not-constant 72*F weather?

I dont. I hibernate and drink lots of tea and keep the seat heaters on all the time. I'll be back