Sooo I thought I had a knock issue going on for a little while now, only when I hit full boost at around 21lbs or so, any other type of driving the noise is not there. Got a buddy to setup his Dashhawk in my car and we went for a couple of rides...noise was there and worse than ever, knock was not...not even a little bit, like surprisingly none at all according to him.

The noise is far worse than it was when it started almost a month ago now, sounds like a mixture of a blender chewing up something soft plastic or like an electric lighter clicking over and over really fast. It seems like it's not there or barely the first hard run or two in the car, then gets progressively worse if I do three or four runs at full boost (don't normally rev past 5k, runs are in 2nd and 3rd gear) to the point I won't hit full boost anymore for fear of blowing some **** up.

Thoughts? Is one side of my turbo eating ****? Does a coil pack sound at all like this when it is failing? The car has been missing occasionally at idle but usually only when it's cold. Could it be my BPV fluttering or the solenoid?

The car seems like it pulls fine when the noise occurs, I don't glance at my boost gauge much but when I do it's reading a steady 21PSI. Anyone with solid mechanical know-how please feel free to chime in!! (maven I'm looking in your direction) I'm just trying to get a feel for the ass-raping I'm in for at the dealer when I finally take it to them.

 

you know...you have a warranty for a reason

 

Not unless he has a second ECU he doesn't...based on his signature pic he's tuned . Anyways, while I think about it I'll give ya a bump so this stays near the top. Maybe someone knows the answer off the top of their head .

 

have you tried returning to a stock tune?

 

Not anymore I don't, I voided it once the tune went in and I'll man up and pay for the **** I break...GM has enough on their table, haha. I was just hoping yee old LNF would be slightly more reliable and I could stretch out spending money on it until I turn the thing into a track only beast...we can rebuild it...we can make it better...lol.

On the way to the gym tonight I took it up to 5500RPM in 2nd once, easing into full boost around 3800RPM. The noise happened like this, ...tssttssttssttsst....tsst...tsst before shifting to third and getting off the boost. Like a ticking with a S sound mixed in. It's more pronounced in third gear but I think that's just because I'm at full boost for a wider chunk of the RPM range.

Boost stayed at 21PSI, car pulled like normal...I'm HOPING its a failing BPV that's fluttering or a solenoid that's like "fuckfuckfuckfuck....****...****...I'm breaking." ANYTHING besides the turbo or engine. This weekend I'm gonna take the intake tubing off the turbo and see if the compressor wheel still spins freely with no play...I remember when the turbo conked out on my old '92 GSX and the wheel was sticky and saw more play than a coked out hooker.

"have you tried returning to a stock tune?"

No, I wish I could though. I'd need the handheld dealy back from Trifecta to reflash to stock and I don't want to pay another 200 dollars for it...I'd buy a stock ECM for testing before that.

 

Hearing these horror stories is what prevents me from slapping a turbo onto the old cobalt. I hope the issue isn't a big problem for your wallet. Id say break the motor down and find out what the noise is coming from.

 

Without an audio clip it's really hard to say, but it could be the BPV...sounds like a flutter based off what you're saying, but that's just my 2c.

 

Yeah, I tried to make an audio clip of it...everyone who's been in the car and is somewhat car-literate has heard it but in the clip all you can hear is the rawr of my engine unfortunately.

 

Turbo going out? Maybe...

 

I know that when mine goes up to 25 psi that there is a sound like the turbo is giving out... it kind of sounds like the wastegate is flapping around... but that is because the turbo is actually maxed out and the wastegate isn't strong enough.... Once it settles back to 21psi the car sounds fine...

You might actually be pushing the turbo and maxing it out... You should see this in your hp reading on the dashhawk...

In my case the noise doesn't last long... as soon as the car maxes out, it settles back down... I normally hear it in 3rd and 4th (I am usually not in 2nd that long) and only when I pull (wot)... I would still get the car checked out... or at least post a sound byte so that we can hear it... But it kind of sounds like this may be your issue

 

hgmmmm ... hearing this makes me not want to get an aftermarket tune now. Warranty FTW.

 

A re-tune is not 200?

 

It really depends on the severity of the noise...are we talking more tick or more "flutter". You may just be maxing out the turbo...it's pretty small and that air has to go somewhere.

Have you tried a higher octane to rule out knock? Also, have you had any issues with the fuel pump? Check to make sure it's not leaking oil from the o-ring/seal (it's pretty obvious)...I'm honestly not very familiar with direct injection, but I'm sure that fuel pump leaking (like some of the '08s do) is not good for anything...

 

yeah im pretty sure a stock reflash is like 75. but then you'd have to flash it back to your tune which may be another charge. but its not a completely new tune fee.

 

a retune with the gt tuner is 75 .. 55 from a dealer and you can get it reflashed to stock or any other tune you might have for free from a dealer or if you still have the gt tuner..

also you can get the dealership to check it out .. and if they try telling you it's the tune that caused it then say forget it ... and drive the car away lol if you're not throwing any CEL's it's strange

if you talk to vince about sending you the tuner so you can reflash he might cut you a break

 

Can't you just unplug the battery for a couple minutes and stock will flash itslef back on?

 

haha no .. that just clears codes lol

 

Nice to see an owner manning up for his decision to play with his car....

 

Seriously, I'll second this. Good on you, man.

The morons on this site who say "I BROKE MY CAR (insert at the track/I'm heavily modded/etc here) AND THE ******** AT GM WON'T FIX IT. HALP!" really bother me. Pay to play, kids. If a dealership refuses to warranty you for a non-mod related failure (i.e. rear brakes gone in low miles) or for using the car's functionality within reason (i.e. they see rubber in the wheel well), then yes, that's wrong. If you blow something missing a shift at the track, running too much boost, spraying, etc... MAN UP.

 

Sounds like boost surge.

 

yeah it does but that doesnt explain the ticking..... it could be the turbo being maxxed out ..... I donno how serious your tune is though. IMO i wouldnt let trifecta touch my LNF with a ten foot pole , no offesne but canned tunes are FTL . it could be 100 things Ide have to hear it to know for sure tho.

 

Take it in and see what it is. Pay them for their efforts, the tech, not the dealership.
Tell them not to fix it.

 

you don't think it could be the half shaft do you? does it make more noise when you turn?

 

"you don't think it could be the half shaft do you? does it make more noise when you turn?"

I've though about both of these...once or twice it almost sounded like a halfshaft or a CV boot that was dry and clicking but not really the same noise. I've heard those before and know the noise, it also doesn't make it when turning or ANY other time except when at full boost. It's not a constant noise either, it's like it pulsates.

I'm really leaning towards flutter... I think it's the BPV or possibly the wastegate flapping a little bit. I noticed last night I actually spike to about 23PSI and sort of bounce between 21-22 when at WOT since the weather has warmed up...which is when this problem started. I think the warmer weather is making the ECU command more boost to reach target airflow levels since the air is less dense... I was only spiking to 22PSI and holding at 20-21 when it was cooler out.

I'm gonna baby it and get a Dashhawk next paycheck just to monitor everything...if it checks out then I'm going to try the HAHN BPV plate with a full on BOV setup on a new hotpipe and see what happens. I wanted to eventually go that route anyway, this will just be sooner than planned. If I still have issues after that point...too the dealer she goes and I'll fix whatever they diagnose myself.

Thanks for all the replies!

 

yeah and let us know if they detect the tune themselves on ya or if they don't and fix it for ya!