Shortly after keeping up with an M3 on the highway (fun!), I noticed that my car was making a much louder than normal wooshing noise at high boost - and then I noticed that it was boosting to 27 psi

I've got a Trifecta tune that normally peaks at 22, and the car has run very well for almost a year now. It seems to drive fine when not boosting, and I didn't notice anything obvious under the hood. The car is totally stock except for the tune.

Any ideas? Stuck wastegate? Boost leak? Can a boost leak actually cause overboost?? I've got a long road trip through the mountains planned next weekend and I just hope it's not serious. I'm taking it to the dealership as soon as I can, but I thought I'd get the forum's advice since people here seem to know more about these cars than the dealership

 

You may have blew a charge pipe or cracked the plastic ends of the stock I/C.

 

How does a boost LEAK cause mega boost reading? I must be missing something here.

I found this post you made:

I've gone back to just unplugging the electrical connection to the solenoid, and leaving everything else alone. Yes, there's a CEL, but the car feels awesome with my 23 psi Trifecta tune. I talked to Vince about disabling the evap purge solenoid in software as part of the tune and keeping the long-term fuel trims, but he's worried about the safety and liability issues of doing that, which I can understand.

Still, I've had my evap purge solenoid disconnected (with a few reconnections for testing) for about 3 months with no problems, other than the CEL, and my car has never felt better, so it does seem pretty safe... stupid emissions controls...

Could this be your problem?

BTW, Running over 24LBS is very dicy and could cause you a lot of grief down the road.

 

Yes, I have had the evap purge solenoid disconnected for quite a while now... it's never caused a problem and did not affect my peak boost levels, it just made the power delivery much smoother. The car feels awful with the solenoid connected. But... maybe it has had some sort of long-term impact. This just happened tonight and I haven't had a chance to reconnect the solenoid and take it for a test-drive, but I will in the morning. I'll be very careful not to overboost at all if I can avoid it.

 

Y'all are talking about two different solenoids. HeritageHighRoof was talking about the Evap Solenoid, and Ronn must've been thinking he was talking about the Boost Solenoid.

A boost solenoid may do it. An evap one doesn't affect boost.

 

Does anyone have a picture of these 2 solenoids ? I beleive they are both on the intake.

 

Yep


The Evap solendoid is the one inside the red box. The Boost solenoid is the one just up and to the left of it.



In theory, if either of them go out, you should eventually throw a code.

The boost solenoid would normally be used for controlling bypassing air by simply referencing to manifold pressure, but since it's a solenoid too, it can also be controlled electronically to an extent by the ECU. If this goes out, then the ECU's control over boost and air bypassing would be somewhat hindered. Not saying it's for-sure the culprit, but it's a part of the ECU's boost control tools. I'd also look into a wastegate issue. In addition to that, if you've got a tune that you've had for a while, Vince has updated the boost tables and you may be able to benefit from the revisions.

 

Thanks for the pic. I thought that was it but wanted to be sure

 

In a prolonged run, I've hit boost like that on the original dual tune. The updated boost tables fixed that and also fixed "bleed over" I sometimes experienced when switching tunes. The newer tunes also have the ability to disable the high-idle cat warm up process. It helped my cold engine driveability and having to wait so long until I set off.

 

[QUOTE=ronn;5154278]How does a boost LEAK cause mega boost reading? I must be missing something here.



a boost leak can cause ur turbo to boost more to keep up with what the pressure is supposed to be at the manifold. So if ur tune is for 22 psi, and u got a leak and loosing preasure, then ur computer sees it and makes ur turbo boost higher to maintain the 22 psi. also if it was hot and humid outside, turbo is way louder in that weather. no idea why it would boost so high though, maybe the tune went wonky, i know mine has a few times.

 

[QUOTE=tomj77;5155253]Hold on...the boost is measured in the manifold..it's not measuring the *boost* output at the turbo. So if you have a leak..even if the ECU is "commanding more boost"...you shouldn't see INCREASED boost in the manifold itself. At best, you'll see the *normal* boost, which will be hard to attain with a leak.

 

Is it normal for the Trifecta Tune to throw Evap codes? Ever since I have been tuned I have thrown evap codes and have had the solenoid replaced twice under warranty and it keeps coming back for some reason, is there a fix for this?

 

I've reconnected the evap solenoid and drove around today with the stock tune, and the car feels and sounds normal. It hits about 17 psi, and isn't making the loud wooshing noise. Activate the tune (very briefly) and the extra-high boost and wooshing is back.

I thought a heard a new faint metallic scraping sound while cruising at light boost, but hopefully that's just in my head. I immediately imagined the turbo on it's way out... but a few seconds of 27 psi won't cause damage... will it?

So because the tune file can't suddenly go "bad", I'm guessing there's a mechanical problem that is only exposed when the tune tries to command more boost than stock. Does that make sense?

 

Nope. In fact Vince has refused to touch the Evap system in any way, even when asked.

I agree with Ronn. The ECU may try to up the airflow from the turbo to adjust, but that wouldn't result in higher boost. All boost is is air stuck between the turbo outlet and intake manifold, so a leak would always lower that, since the air would be escaping.

 

"new faint metallic scraping sound" it maybe the valves or springs gone limp or going bad.. i know the sound and it sucks.. new springs/ valves/install $1200+

boosting over 27, can cause the valves to float (valves getting "pushed" open from to much boost) or the spring sag (the spring losing its "load" to open or close the valve properly).. once the valve hits the piston game over..

 

Well, on a whim I reflashed my ECU with a slightly less aggressive version of my Trifecta tune - peak boost is a bit lower, and it seems to build boost more gently.

The car runs fine now, both stock and with the tune activated. It hits 21 psi really consistently with the tune, and there's no odd noises. I'm thinking that something must have gotten "stuck" for a while when I was having the problem, and has "unstuck" itself

The car would probably be fine even with the more aggressive tune, but I'll stick with this mellower version for now. I'm sure this isn't the last I see of this problem (it's rare for something to completely fix itself!) but I'm happy my car is running well again.

 

I was actually doing this last week in 100* Houston weather with my GM stage 1 tune....I also am having the famous surging issue at times with 5lbs max boost and sometimes 0 boost at WOT. I am having my lower TMAP sensor soldered and wrapped this week. Could I also have a leak?

 

My car felt good and sounded normal for a few days, but the whooshing noise is back, and I've seen some unusually high boost again.

You know the psssshhhh sound the BOV makes when you're at full boost and let off the throttle? - my car makes that sound all the time at high boost (above 16 psi) and when I let off the throttle, it doesn't sound any different, the psssshhhh just continues for a fraction of a second.

It's still running OK, but something feels wrong. Could the BOV be leaking? How would I diagnose this?

 

Float is caused by engine RPM. If the engine is spinning faster that the valve can close, you need stiffer springs to close it faster. Stiffer valve springs are used to take advantage of higher RPMs which, in turn, take advantage of better turbos. But 27 PSI won't cause float if the engine RPM isn't exceeding the stock redline unless there is excessive wear and/or under oiling of the valve train. But you are definitely correct about valve vs. piston battles... No matter how it ends you lose lots and lots of money.

The BOV or BPV, whichever you have, will make noise when venting, bov vents from the intake to teh outside air, bpv vents from turbo to downpipe. That part is normal. If you are seeing higher than normal boost something isn't allowing venting. Maybe your BPV is not opening all the way. Getting up to 27 psi can cause damage. It can cause your engine to run lean, thereby causing knock which will blow rings, valve seals, or head gaskets.

But what feels wrong?