# Squeak/squawk during blow-off & occasional loss of boost



## WillL84 (Aug 5, 2019)

Nothing yet that I've noticed on my '17. I'm only at 12k miles though and stock and no tune yet


----------



## PolarisX (Dec 17, 2017)

Remember that if you have KR the engine can cut timing or boost, since on the LE2 its electronically controlled. Severe loss of power events can be LSPI, which can drop a ton of timing and almost all of your boost. Seeing KR is diffucult unless you are datalogging (or viewing total KR events) as sometimes it only shows for a second or even less until its resolved by the ECU. I also moved to the turbo elite tune from Trifecta when I got my AEM intake. They did send me a revised tune with the right MAF table for the AEM intake. Even though the Advantage tune seems to handle it, its not quite right. Then again Advantage is for 100% stock cars.

That said, I do know the sound you are talking about where if you are over about 12 PSI and close the throttle quickly you got the normal 'woosh' sound with almost a honking noise.

I also noticed a positive change moving to the newer 41-156 spark plugs.


----------



## Gerst (Mar 9, 2020)

PolarisX said:


> Remember that if you have KR the engine can cut timing or boost, since on the LE2 its electronically controlled. Severe loss of power events can be LSPI, which can drop a ton of timing and almost all of your boost. Seeing KR is diffucult unless you are datalogging (or viewing total KR events) as sometimes it only shows for a second or even less until its resolved by the ECU. I also moved to the turbo elite tune from Trifecta when I got my AEM intake. They did send me a revised tune with the right MAF table for the AEM intake. Even though the Advantage tune seems to handle it, its not quite right. Then again Advantage is for 100% stock cars.
> 
> That said, I do know the sound you are talking about where if you are over about 12 PSI and close the throttle quickly you got the normal 'woosh' sound with almost a honking noise.
> 
> I also noticed a positive change moving to the newer 41-156 spark plugs.


Good point about KR potentially cutting boost. I have been monitoring it via Torque, but was previously using a standard dial gauge, which as you said only shows it for a second. I recently switched to a line graph that shows about 10 seconds worth of data, but haven't been using that for long. I'll keep an eye on it if I get another loss of boost. I didn't notice any other symptoms of LSPI at the time, but it's a definite possibility.

Also interesting what you said about moving to the Trifecta Elite tune. I got the Advantage tune first, then installed the intake and asked Trifecta directly if I should upgrade to the Elite tune - they said there was essentially no point. How long have you had your tune? I know their offerings have evolved some over the years, based on reading I've done.

A 'honk' is another good way to describe the noise. I'm guessing we're hearing the same thing. I might make a video later today so everyone else can hear it. It's not something I've ever been able to hear in other videos that are out there of the AEM intake. How often does your car 'honk'? As I said, mine seems quite frequent - probably half the time I let off the gas, and it will happen with as little as 6-7 PSI of boost. It's really quite annoying.

Lastly, regarding spark plugs... this thread had me thinking that 41-153s are the right ones for the gen 2 Cruzes. I actually ordered the NGK-equivalent ILNAR8B7Gs this past weekend. What caused you to use 41-156s?


----------



## Blasirl (Mar 31, 2015)

Posting a video of the noise might help.


----------



## Gerst (Mar 9, 2020)

Alright, went for a short drive and grabbed some video. Part 1 has three shifts that illustrate the problem well. The first blowoff is moderately squeaky, the second is very squeaky, and the last is clean (minimal-to-no squeak). Part 2 has plenty more examples, from totally clean to loud squeaking.


----------



## PolarisX (Dec 17, 2017)

Yeah mine doesn't sound like that. I would take off your BPV and inspect it.

If you do get the BNR recirc you will need a different tune as it fiddles with the way the turbo works on a mechanical level.

The 41-156 was the latest plug specified for the GM SGE engines. 41-153 was superseded to 41-156. I do have a suspicion the NGK plug you bought IS a 41-156 though, because the ones I got were NGK plugs in an AC Delco box.


----------



## Gerst (Mar 9, 2020)

We seem to get conflicting information from Trifecta. I asked earlier today, and they claimed that the Advantage tune would handle the BNR valve fine - I would just need to re-flash after installing it. I'm not sure I feel comfortable with that idea however...

To be honest, I prefer the OEM valve's single crisp blowoff note to the BNR valve's flutter (at least when mine isn't squeaking). I will inspect and clean my BPV tonight, see if that makes a difference, and report back.


----------



## PolarisX (Dec 17, 2017)

Weird, BNR says you need to tune for that valve, that is why I assumed that part would require changes verses the stock BPV.


----------



## Fireworks234 (Jan 4, 2018)

Gerst said:


> We seem to get conflicting information from Trifecta. I asked earlier today, and they claimed that the Advantage tune would handle the BNR valve fine - I would just need to re-flash after installing it. I'm not sure I feel comfortable with that idea however...
> 
> To be honest, I prefer the OEM valve's single crisp blowoff note to the BNR valve's flutter (at least when mine isn't squeaking). I will inspect and clean my BPV tonight, see if that makes a difference, and report back.


I specifically asked them if I would need my tune changed for that part and they said I *would* after initially saying I wouldn't. They were inadvertently thinking of the Gen 1 that doesn't require any tuning to install a similar part.


----------



## Gerst (Mar 9, 2020)

Fireworks234 said:


> I specifically asked them if I would need my tune changed for that part and they said I *would* after initially saying I wouldn't. They were inadvertently thinking of the Gen 1 that doesn't require any tuning to install a similar part.


Thanks for the information. I could definitely see that being the reason for the confusion, as I'm sure they have far more gen 1 customers overall. Did you ever end up installing the BNR valve on your car?

In other news, I failed to remove my BPV last night. The third screw beneath the valve is a real PITA to get at, and I don't have a tool that fits into the available space. I ordered a particular socket adapter that should help - it will be here tomorrow.

Anyone with experience removing the BPV on our cars have any tips or tricks for getting at the screws? I've just been going by BNR's guide. I'm a bit concerned about being able to get the bottom screw back in without dropping it into the engine bay.


----------



## JDH412 (Mar 10, 2020)

I installed the BNR valve about a month ago on my 2017 Cruze so I know your struggle. The stock valve is a PAIN to get off because of that third screw below it. I used a small allen wrench to get to it and basically just felt around since you can't actually see anything until I got it onto the screw. Once you yank it lose (which is not easy and takes some strength) you can use your fingers to get it out the rest of the way while being careful not to drop it into the engine bay.

Putting the new BNR valve on was just as difficult unfortunately because of that bottom screw location. If I had a better tool to use I'm sure it would have been much easier but the only thing i could get to work in that limited space was a really small allen wrench.


----------



## Gerst (Mar 9, 2020)

JDH412 said:


> I installed the BNR valve about a month ago on my 2017 Cruze so I know your struggle. The stock valve is a PAIN to get off because of that third screw below it. I used a small allen wrench to get to it and basically just felt around since you can't actually see anything until I got it onto the screw. Once you yank it lose (which is not easy and takes some strength) you can use your fingers to get it out the rest of the way while being careful not to drop it into the engine bay.
> 
> Putting the new BNR valve on was just as difficult unfortunately because of that bottom screw location. If I had a better tool to use I'm sure it would have been much easier but the only thing i could get to work in that limited space was a really small allen wrench.


Good to hear that I'm not the only one that struggled with it. I'm hopeful that I'll be able to get in there with a 1/4" socket using a 3" extension and an H5 bit on an adapter. We'll see tomorrow.

How do you like the BNR valve? Do you have an intake on your car? How would you describe the new sound compared to the OEM valve? Are you running a BNR tune as well? Sorry for all the questions, hope you don't mind!


----------



## JDH412 (Mar 10, 2020)

Gerst said:


> Good to hear that I'm not the only one that struggled with it. I'm hopeful that I'll be able to get in there with a 1/4" socket using a 3" extension and an H5 bit on an adapter. We'll see tomorrow.
> 
> How do you like the BNR valve? Do you have an intake on your car? How would you describe the new sound compared to the OEM valve? Are you running a BNR tune as well? Sorry for all the questions, hope you don't mind!


So far I love it, and yeah I have a K&N intake that I installed a couple months before putting the valve on. The intake itself was already pretty loud and after putting the valve on it's honestly pretty hilarious how it sounds. My car is a 6-speed and after every shift I can hear it, at high boost it chirps like crazy after letting off the throttle. Sounds like a UFO. The OEM valve was silent in comparison I could only hear it with the windows down and at full throttle. 

I do have a BNR tune and after buying the valve they'll send an update for your custom tune so that the new valve doesn't throw any codes after you install it.


----------



## Fireworks234 (Jan 4, 2018)

Gerst said:


> Thanks for the information. I could definitely see that being the reason for the confusion, as I'm sure they have far more gen 1 customers overall. Did you ever end up installing the BNR valve on your car?


No, still haven't gotten around to buying it yet. Life getting in the way and whatnot lol. I still think I'd like to do it but probably going to wait until the summer now.


----------



## PolarisX (Dec 17, 2017)

I'd love to try the BNR recirc, but man $250 is steep.


----------



## Gerst (Mar 9, 2020)

JDH412 said:


> The OEM valve was silent in comparison I could only hear it with the windows down and at full throttle.


It's interesting that you say that, I feel like mine is quite loud already. I can clearly hear the blowoff from as little as 3 PSI of boost, even with the windows closed. The videos I posted above were with the windows closed. Perhaps the difference is the K&N vs. AEM intake? Did you watch the videos? How does my car sound compared to yours before you put on the BNR valve?

As I said previously, I honestly think I prefer the single crisp blowoff from the OEM valve + AEM intake to the flutter from the BNR valve (assuming I can eliminate my squeak). However, I haven't found any good videos of what the BNR valve sounds like from inside the car to compare with my own experience.


----------



## JDH412 (Mar 10, 2020)

Gerst said:


> It's interesting that you say that, I feel like mine is quite loud already. I can clearly hear the blowoff from as little as 3 PSI of boost, even with the windows closed. The videos I posted above were with the windows closed. Perhaps the difference is the K&N vs. AEM intake? Did you watch the videos? How does my car sound compared to yours before you put on the BNR valve?
> 
> As I said previously, I honestly think I prefer the single crisp blowoff from the OEM valve + AEM intake to the flutter from the BNR valve (assuming I can eliminate my squeak). However, I haven't found any good videos of what the BNR valve sounds like from inside the car to compare with my own experience.


I meant before I installed the intake when the car was stock it was quiet, sorry if that was confusing. The K&N intake by itself was very loud, the BNR valve basically just amplified the blow-off noise and gave it a much clearer turbo flutter sound. 

Your car does sound very similar to how mine sounded when I just had the intake, although I never had any strange squeak noises or losses of power that you're experiencing. I'm no mechanic so I'm not sure what the issue is, but It's definitely worth a shot to check out the OEM valve and see if it's dirty or sticking or something though.


----------



## RoninDusette (Aug 21, 2018)

To me it flat out sounds like your bov is not even opening but a little bit. Too much spring tension or something. Check vac lines running to it for integrity (holes, cracks, kinks, clogs). It should for sure not chirp like a dog with a shock collar. That would also cause back pressure in your intake pipes* from the leftover air being under pressure and having nowhere to go, taking the path of least resistance, which is back the other way through your turbo, which is causing the bearings to squeal, which is going to wreck your turbo. That is just what it sounds and looks like to me. If the bov is adjustable, adjust it "out" or whatever is more loose. Yes, it's controlled via a solenoid, but the mechanical part for it can be tuned to suit. I would go that route. That high pitched squeal sounds exactly like bearings meeting a journal.


----------



## Gerst (Mar 9, 2020)

Alright, got in my socket adapter last night - worked a treat in being able to get at those tricky screws. For anyone else trying to do work on your BPV, I highly recommend getting yourself some way to put an H5 driver bit onto your 1/4" socket. I used one of these adapters with the H5 bit from this set. 

Once I got the valve removed, I inspected it - seemed to me like it could use a bit of lubrication, as the piston would bind ever so slightly as I moved it up and down. I went to take it apart following BNR's instructions for the HPRV, and unfortunately put a tiny crack in the plastic of the piston housing, right next to the O-ring on the inside. The instructions suggested prying with a screwdriver around the edge where the O-ring was - I would NOT recommend this. The plastic at that edge is extremely thin and cracked under minor pressure from a flathead bit. Ultimately I applied a bit of WD40 in the crack where the O-ring was and was able to pull out the piston assembly with my fingers, using a twisting motion.

The crack is really tiny, and I don't believe it's in a critical spot on the valve. However, it's on the inside of the valve, so if the weakened integrity of the plastic caused a piece to break off, I imagine I could be looking at damage to the turbo internals. I really should have taken a picture to post here to get CruzeTalk's input.

The way I see it, I have three options:

Re-install the existing, newly lubricated valve in spite of the tiny crack
Replace the valve with a new OEM part ($120)
Replace the valve with the BNR HPRV ($250 + $600 for BNR tune... ouch)
I'm leaning towards #2. #3 seems wasteful considering that I already have a Trifecta tune, and I'm not sure I actually like the HPRV flutter noise. #1 is just risky.

What does CruzeTalk think? Anyone else ever taken apart and caused minor damage to their BPV?


----------



## Gerst (Mar 9, 2020)

I just reached out to Trifecta (again) to explicitly confirm the compatibility of their tunes with the BNR valve on the gen 2 Cruze - I thought you all might be interested in the response:


----------



## Fireworks234 (Jan 4, 2018)

Gerst said:


> Alright, got in my socket adapter last night - worked a treat in being able to get at those tricky screws. For anyone else trying to do work on your BPV, I highly recommend getting yourself some way to put an H5 driver bit onto your 1/4" socket. I used one of these adapters with the H5 bit from this set.
> 
> Once I got the valve removed, I inspected it - seemed to me like it could use a bit of lubrication, as the piston would bind ever so slightly as I moved it up and down. I went to take it apart following BNR's instructions for the HPRV, and unfortunately put a tiny crack in the plastic of the piston housing, right next to the O-ring on the inside. The instructions suggested prying with a screwdriver around the edge where the O-ring was - I would NOT recommend this. The plastic at that edge is extremely thin and cracked under minor pressure from a flathead bit. Ultimately I applied a bit of WD40 in the crack where the O-ring was and was able to pull out the piston assembly with my fingers, using a twisting motion.
> 
> ...


Thanks for the tips. And in regards to your questions, I'd suggest 2 or 3 (also ouch). I hate reattaching broken pieces but sometimes you have no choice. If you have the choice, I'd definitely avoid reattaching over-stressed components. Good luck and keep us updated.


----------



## PolarisX (Dec 17, 2017)

I would do #2 here, and investigate #3 down the road. Get the car running correctly before you change any more variables. If you buy the BNR non returnable unit and find out its not the problem... Well I'd be kicking myself pretty hard.

Trifecta support is great - Michael always answers my questions in a timely manner.


----------



## Gerst (Mar 9, 2020)

Thanks for the input folks - I ordered a new OEM valve yesterday evening and will report back once it arrives and is installed.


----------



## PolarisX (Dec 17, 2017)

Keep us in the loop. Good luck!


----------



## Gerst (Mar 9, 2020)

The new OEM BPV arrived today. Gave it a tiny bit of assembly lube, got it installed... and started hearing the same squeaky turbo farts within 5 minutes of getting in the car.

Well, ****.


----------



## PolarisX (Dec 17, 2017)

Put the stock air box in with the bottom off. See if its the same. You should still be able to hear the blow off (Recirc). Don't drive too far like that, the filter is only retained by a little clip without the rest. Rule out the intake the tubing 100%.

At least you didn't order the BNR one to have fluttery squeak farts.


----------

