P0299 Turbo under boost. Build boost very slowly.

[justwantv]

New to me 2019 SQ5. 52k miles. I got a boost fault one night on the way home from work. Cleared it with my Carista dongle. The car seemed to never really be 100% since. For instance when you floor it the boost gauge will slowly, painfully raise until finally you feel a surge. Once you are finally making boost it seems fine. From a stoplight driving moderate to spirited letting it shift at say 4.5 or 5k the trans is late in 2nd before your really making enough boost to go anywhere. I've been waiting to throw another code. Either another boost fault to confirm it is not just me or some other fault that would shut boost off as a consequence. Like misfire, cam timing etc.

Once it throws the low boost fault it is even more of a turd until the key is cycled. Once I had the throttle wide open for several seconds in a higher gear bogging the engine and I got turbo over speed fault.

The crank case has a lot of pressure. When you remove the oil fill cap while the engine is running it has a lot of pressure behind it. Not sure how much pressure it should be. Seems like it should only be a few mbars though. I smoke tested to see if there are any leaks. None found. The waste gate actuator moves freely and holds vacuum when applied.

I have read there could possibility be some issues with the vacuum solenoids that are on the front of each cylinder head. Like getting gunked up with oil from the vacuum pump??? I work a ton and it's my daily so kinda wanted to see if you guys knew anything common before I start taking stuff apart. No need to reinvent the wheel if it is a common problem. It seems very common on the 2.0 4 banger but not so much google info on the 3.0 V6.

Any info or experience with this issue is very appreciated.

PS please don't ask me if I am driving in S or D. Yes it does it in S and I am setting fault codes.

[DiscoDan]

Are you driving in D or S?

[GoCougs1234]

Can you be more specific - by crankcase "pressure" do you mean positive or negative pressure? With the engine idling, I've only ever seen vacuum in the crankcase - so much so that it is difficult to remove the oil fill cap, and when I do remove it, the engine idles very poorly.

I was having overboost (only) issues a few weeks ago and it turns out it was a vacuum leak that didn't show up during a boost leak test due to 1) check valve and 2) the leak was only present when the connector was jostled (such as when WOT shifting which is when I was getting the overboost DTC). See the highlighted connector below (where I was having my issues).

There are a number of connectors like this throughout the engine - both upstream and downstream of the turbo and then related to the PCV system (here's an excellent link that illustrates the various connections: https://www.yumpu.com/en/document/re...5/ssp655-wg-en). These connectors are very poorly designed IMO. My issue is not your issue, but may be related. I found my problem only after the connector popped off initially, and then after reattaching it, jostling it by hand at idle, to then clearly hear the vacuum leak ($130 for a new hose assembly fixed all).

[justwantv]

Positive pressure. When this first started I could tap my finger on the tiny hole on the crank case vent valve and get a little hiss out of it. It was cheap and easy enough as well as a know issue on the old supercharged V6 so I replaced it. I thought surely it would fix the pressure issue and fingers crossed it would fix the boost fault issue also but nope.

Thank you for the literature link. I will read it cover to cover.

One of the biggest problems is time for me. I work a ton and have a demanding family life I am grateful for but definitely keeps me busy from wake to bed. But I will keep this thread updated.

If anyone has had similar issues or has ideas please let me know.

Thanks

[GoCougs1234]

In aforementioned tube assembly I replaced there is a check valve - if that is bad it would allow pressure from the charge pipe (i.e., highlighted tap) that could perhaps cause such a problem but a turbo typically doesn't supply boost at idle. As you'll see in that doc, there are many hoses and taps for the PCV system, and probably other check vavles and such, so perhaps that is where the issue lies. Unfortunately a number of those hoses and connectors take a LOT of work at get to. Unfortunately, another way a crankcase gets pressurized is via an internal engine failure - bad rings, hole in piston, etc. - which is readily evident at idle: https://www.youtube.com/watch?v=OLHEJMJ0to0&t=28s

[justwantv]

Attachment 303717Attachment 303718

[justwantv]

Fixed!!!!
So like I said before it built boost super slow. You could watch the gauge struggle to get to only the low boost mark at times, middle of the boost gauge most the time and rarely to the “max” hash mark. Now once you see the boost line it takes maybe a second to peg full boost!

So what was it?

The vacuum pump has two ports. One small and one large. The large one goes to the brake booster. The smaller one has a vac hose the connects it to a t fitting. The hose the goes from the vacuum pump to the t fitting had a smaller clog. With a vacuum pump I tested it and it would draw air but very restricted. I blew out a piece of orange copper color waxy oil the size of a large piece of rice or maybe a single rat poop pellet. I’m guessing depending on temp the oil would get viscus enough to let more or less vac through. The oil likely came from where it attaches to the intake tubes. None the less cleaned it all out and BACK IN THE GAME.

Just wanted to,fix this before the tune. By the end of May I’ll have an Integrated Engineering tune on it.

[GoCougs1234]

Nice catch. Lots and lots of vacuum stuff in the system. To me it doesn't sound like oil - maybe something left over from manufacturing? Who knows.

[Chard]

Coincidentally, I’m getting this issue now. P0299 code, loss in boost. I can get a tiny bit on the gauge but nothing more. Then it’ll intermittently work and I’ll get full boost. Thought it was the dv, so replaced that. Worked for 2 days and then got the warning again and loss of boost.

I can’t tell where the vacuum pump is in your diagram. Would you mind posting a pic of the whole engine bay? I’d like to check the same hose. How’d you get to it?

Sorry, I’m new to this platform so still figuring my way around it.

[GoCougs1234]

Coincidentally, I’m getting this issue now. P0299 code, loss in boost. I can get a tiny bit on the gauge but nothing more. Then it’ll intermittently work and I’ll get full boost. Thought it was the dv, so replaced that. Worked for 2 days and then got the warning again and loss of boost.

I can’t tell where the vacuum pump is in your diagram. Would you mind posting a pic of the whole engine bay? I’d like to check the same hose. How’d you get to it?

Sorry, I’m new to this platform so still figuring my way around it.

Check out this awesome link (vacuum pump shown on p. 24): https://www.yumpu.com/en/document/re...5/ssp655-wg-en

[JonnyBravo!]

I'm getting this code now after replacing my coolant shut-off valve and solenoid valve. One thing after another...

[Chard]

Check out this awesome link (vacuum pump shown on p. 24): https://www.yumpu.com/en/document/re...5/ssp655-wg-en

That link is awesome, thanks for sharing!

My car mysteriously resolved this on its own. It's been about almost a week of normal boosting without warnings or CEL so I'm remaining cautiously optimistic.

[Chard]

I'm getting this code now after replacing my coolant shut-off valve and solenoid valve. One thing after another...

Car has just gone back to losing boost again. I can get the gauge to show 1 led, but that’s it, it’s driving like it’s naturally aspirated. Did you figure out the cause for your car?
I’m thinking it could maybe be the n75 now…
Haven’t heard any weird whistling/howling so I’m hoping it’s not the turbo or wastegate.

Since it’s intermittent and I’ve gone a couple weeks straight with normal boost, I’m confused.

[JonnyBravo!]

Car has just gone back to losing boost again. I can get the gauge to show 1 led, but that’s it, it’s driving like it’s naturally aspirated. Did you figure out the cause for your car?
I’m thinking it could maybe be the n75 now…
Haven’t heard any weird whistling/howling so I’m hoping it’s not the turbo or wastegate.

Since it’s intermittent and I’ve gone a couple weeks straight with normal boost, I’m confused.

Still happening. I replaced the N75 and that didn’t work. I get the “wastegate stuck open” code, but I assumed it was an error. Now I’m starting to think maybe it is the wastegate. Just odd that I never had these issues until I replaced the coolant parts. I’m sure it’s something I screwed up.

[Chard]

Where’s the n75 on this car…do you have the part number? I reached out to ECS and they said there isn’t one.

[JonnyBravo!]

Where’s the n75 on this car…do you have the part number? I reached out to ECS and they said there isn’t one.

It's on the passenger side, next to the solenoid valve. ECS actually carries it, but I found it cheaper elsewhere...

https://www.ecstuning.com/b-genuine-...er/06m906609a/

https://www.audiusaparts.com/oem-par...rter-6m906609a



I feel like I hear some whistling noise, so maybe it is my wastegate.

[Chard]

Thanks, I found the part number for this online after a lot of research. There isn't much info on these cars yet it seems. Anyhow, part number is 06M 906 609 A for anyone looking in the future.
I have it on order and it should be here in 2 days. Hope this fixes the boost issue at least.

The other issues are narrowing down to the water pump, thermostat, and coolant switching pump.

Symptoms: low level coolant in reservoir, see dried coolant on the N649 valve and around the area, and no boost (suspect coolant got into the N649 vac line and also into the N75 vac line). Not getting any overheating or low coolant warnings.