It's been pretty cold here. Today it was maybe... 15 out with a windchill of well below zero.

I was driving home from my sisters. It's been quite a while since I've done any WOT with the car. (I'm tuned btw) So I did in 3rd for just a bit at about 50 mph. It happened pretty quickly but I noticed boost only rose to about 17 psi vs. the 22ish that I usually see. Then without any noise that I heard, and yet VERY VERY rapidly the boost just dropped completely. The rest of the way home it would only go to 0 psi and no more.
I got home, checked out all the lines and fittings and all seemed well. Started the car back up and took a quick spin. All was well again. I didn't WOT but made it hit 10-15 psi and it did fine.
The weird bit is I never saw any CEL or messages like "reduced engine power" or anything. Unless that message flashes and then disappears. If that's the case I probably just missed it.

I'm guessing it was just the cold and the turbo didn't like moving the dense, cold air causing the ECU to basically say "up yours".

I'm not too worried about it, just curious.

Thoughts?

 

It doesn't get that cold around here but I did go into reduced power mode on a cool night a while back. I got a cel and it flashed on the dic. It happened after a NLS shift and full throttle pull. After about 5 min every thing was fine.

 

Sounds to me like your charge piping is loose, and or not properly fastened, I would start by checking there first.

 

I had this same thing happen to me on a rainy day, once. It never happened again, and I never figured out what it was.

 

It was -7 here in Chicago yesterday morning...drove my car like normal and no issues to report (a few WOT pulls). I don't think it is the temperature...sounds like your piping must have come loose...

 

1) You're going to run less boost in colder temperatures that's normal
2) You might have a boost leak somewhere, or your custom tune is too agressive for excessively cold weather. It may have cut boost to protect the motor against damage but unless you have someone data log it it's tough to say

 

I had the same issue with the cold weather after I gotten my GMS1 done. The temperature in the Southeastern North Carolina started dropping. I notice my boost went from 22psi to 15psi. It would studder to go past 15psi, unless fully warmed up. You should be good. My charge pipe is fine. Highly doubt its loose.

 

I'm tuned at 22 psi and I don't go past 19 ish. I think it's just because of the cold weather. I'm sure once it warms up you'll be fine.

 

Been boosting 24 psi on my tune in 0* f weather no problems. Traction is an issue... well, the clutch too.

Stock intake? I forget your setup.

 

I'm tuned for Fall weather and with how cold it is I'm seeing knock just at part throttle casual acceleration. I'm de-tuning this weekend. It's a mix between this shitty winter blend gas and the cold weather. A tuned car is going to keep trying to make the same power it did in warm weather but it's having to boost less and I figure this is throwing to ECU off somewhere we can't see and it's doing something to cause major knock. I've recorded up to 10 degrees of knock on a WOT run in this weather, I will NOT be going WOT again until spring

 

i do pulls in -20, it always boosts to 22psi, if ur on tune it should boost all the way to what ur tuned at. there is no learn down, so it wont compensate for colder weather, if ur on stock tune its a diff story. do u have select a tune? cause i notice sometimes when i turn it on while driving it doesnt quite want to make the total transition to the tune, and it boosts only to 17ish, then i turn the tune off and back on and all is good. how soon after u left ur sisters house did u do this pull? was ur car at running temp? sometimes when u do a pull when ur car is cold, the engine light will flash a few times, u will loose power, and stay like that till u turn ur car off and back on, iv seen that to.

 

It just did it again tonight, this time with a code. But I have no way of reading it right now.

I noticed it again stayed around 16-17 PSI and the fault happened at nearly 5K rpm dead even.

How do I go about finding this leak? Everything looks in tact and it does hold a certain amount of boost. Hmmmm...

Yep, no bolt ons. Just the tune right now.

I mean I did the airbox mod with the snorkel and vacuum tank bypass but that's been quite some time ago.

 

Almost sounds like a wastegate problem. If the wastegate was sticking partially open, that would explain your low boost, and sticking fully open would explain why it wouldn't go above 0 PSI. I'd imagine its controlled by the PCM with a solenoid or actuator, which would explain why it set a code.

Get the code scanned and then it will be much easier to diagnose the issue.

 

Put the vac tank back in service. Having it bypassed on mine hurt more than helped. Without it the BPV couldn't open in low vac conditions, really messed with my fuel trims.

 

Ok... sorry peeps. I'd look this up but I'm on my phone and need to get running work.
Code is P0299.

Based on the printout (there's no GM codes on it for some reason) looks like boost leak. I hope not wastegste. In my little bit of research it looks like they usually fail closed...?

Thanks for your help.

 

0299 = Turbo Underboost

leak is sounding very possible

 

Weird I have never seen a underboost code on a stock turbo LNF before.

 

I had one when my couplers and clamps weren't on right on my charge piping. It could be something as simple as that.

 

did you check your charge piping yet for leaks? its the most common issue at the IC.

 

Not yet but I will check all fittings after work just at least eliminate those.
Thanks a lot guys for all your help!

 

Take you hot side charge piping off and put it back on. If that doesn't fix it try the cold side. If that doesn't fix it chances are your IC is cracked.

 

Well I checked everything from the intake to make sure nothing was blocking air coming in, all the fittings to the throttle body. I made sure they were all tight.

I took out the clips underneath the car so I could visually check for rips or tears and feel around. Everything seemed fine that I could see.

I did find this to be pretty suspicious and removed it, looked for cracks, etc and put it back in. It's the vac line going to the brakes. It's saturated with oil on the first 2 inches or so next to the intake manifold.

After doing all that it still won't hold ANY boost whatsoever. Granted the code is still in there, the CEL is still on. I guess I should disconnect the battery and clear that, then try again. I don't know if the ECU would just prevent boost from building if the code is in there.

EDIT: I cleared the code but still... nadda... doesn't hold ANY pressure whatsoever. Ugh...

 

Time to bring her in.

 

Hmmm... I've been thinking about this. I was thinking maybe the BPV is ripped or torn. (I can check it just in case I guess)
Without TOO much knowledge on the issue, maybe I have the bad piston (#1) that others have been seeing and am getting massive blowby causing the oil saturation. Anyone else thinking that perhaps?

Oh, on a side note, money actually IS an issue here because I'm beyond 36K miles. So not EVERYTHING is covered.

 

if your car won't hold any boost and ur punchin it ..then you have the same problem as mine. They have an actuator (what i was told) that relates to the turbo and is broken with the intake pipe so it won't hold any boost. my check engine light came on like an hr later

good luck btw getting the replacement part. its on a national back order and i haven't had my car is 3 weeks. Not happy..