Troubelshooting: BOV Opening Under Acceleration

SRT82ECOBOOST · July 25, 2014, 06:42:00 AM

I just got my car back about three days ago from the dealership after a rather lengthy stay in which they found absolutely nothing wrong with my car. I have left the car running the stock tune. I have been driving it around just in town without a chance to open it up, but something felt a little off. So yesterday I got a chance to really get on it and the car felt incredibly slow. Not to be one to let my butt dyno to define the poor performance, I timed some 0-60 runs and the times ranged from 6.43 to 8.1.
I immediately started to wonder if the vehicle was making any boost and it was confirmed by the Torque app on my phone that it was indeed making boost. Not knowing my ass from elbow with these engines, first thing I decided to do was to make the rear BOV vent to atmosphere. Sure enough that under acceleration from 1/2 throttle to WOT, the entire time that the pedal is pressed, the BOV is dumping what could be all the boost.
Before I head back to the dealership and have them start what will probably be a long troubleshooting session, does anybody have any ideas as to why this is happening?

glock-coma · July 25, 2014, 07:20:10 AM

I'm pretty sure the front and rear blowoff valves are interchangeable.
you can try swapping them and seeing if the problem goes to the front or stays in the rear.
if it stays in the rear somethings telling the blowoff valve to open and it's not a defective valve.

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SRT82ECOBOOST · July 25, 2014, 10:40:38 AM

Just pulled the negative side of the battery post off for a half hour and hoped the car would come out of its funk. No luck to be had though.

Jtrain · July 25, 2014, 10:50:57 AM

This is where you have to test your relationship with your dealer. These Blow off valves are electronic (Which sucks). So you can either tell them you were tinkering and see if they'll go straight to the problem-- or play it safe and lead them to clues like "Feels like boost isn't there, or a leak" You can preface that statement with you long love for turbo charged platforms (true or not)

Be careful though, BoVs are open more often than you'd really think- especially with a MAP car, it doesn't really matter that their closed until their actually building boost AND accelerating. I hear my car dumping air while I'm barely on the throttle constantly.

You really don't run into problems like this with vacuum activated BoVs: but it's a huge project to switch those out (for no real benefit).

Times like these, almost miss that big ass N/A hemi, eh?

SRT82ECOBOOST · July 25, 2014, 11:03:10 AM

Quote from: Jtrain on July 25, 2014, 10:50:57 AM
This is where you have to test your relationship with your dealer. These Blow off valves are electronic (Which sucks). So you can either tell them you were tinkering and see if they'll go straight to the problem-- or play it safe and lead them to clues like "Feels like boost isn't there, or a leak" You can preface that statement with you long love for turbo charged platforms (true or not)

Be careful though, BoVs are open more often than you'd really think- especially with a MAP car, it doesn't really matter that their closed until their actually building boost AND accelerating. I hear my car dumping air while I'm barely on the throttle constantly.

You really don't run into problems like this with vacuum activated BoVs: but it's a huge project to switch those out (for no real benefit).

Times like these, almost miss that big ass N/A hemi, eh?

I previously ran the BOV VTA mod and never heard it open while under acceleration. Never made a peep unless I was getting off the gas.

ShoBoat · July 25, 2014, 11:04:49 AM

Just a thought, if they were messing around with the turbos you may have a loose hose clamp on the hot side. It may have nothing to do with the BOV at all.

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SRT82ECOBOOST · July 25, 2014, 11:07:42 AM

Quote from: ShoBoat on July 25, 2014, 11:04:49 AM
Just a thought, if they were messing around with the turbos you may have a loose hose clamp on the hot side. It may have nothing to do with the BOV at all.

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After noticing the lack of power I did the BOV to VTA mod and the boost is definitely being dumped out the BOV. I am going to test the front BOV and see if that is dumping boost as well.

ecoboostsho · July 25, 2014, 12:04:50 PM

I watch the % open/close blowoff valve occasionally and it is often partially open (or closed). I couldn't hear it either when I was VTA (I'm not anymore) unless it dumped all of the boost. I would expect that dumping some of the air is normal to maintain required pressures. If you had Torque or a laptop with forscan you could look at desired vs. actual boost to see what was going on. I would definitely check the pipes as well...

SHOdded · July 25, 2014, 12:39:56 PM

Exhaust is also completely stock at this moment right? Could too little/too much backpressure be a problem in this case?

SRT82ECOBOOST · July 25, 2014, 12:48:36 PM

The exhaust is a custom catback. The car ran great when I first dropped it off at the dealership and now that I have it back I am running into the issues associated with this thread.

Jtrain · July 25, 2014, 12:56:21 PM

Just take it back and let them know.

jkeblaitis · July 25, 2014, 04:14:58 PM

It could be a loose hose, I had a loose hose under the drivers side of engine, i would hear boost leak at WOT until it came completely off after a while of driving... it kinda sounded like the blow off valve was stuck open

IHeartGroceries · July 25, 2014, 04:30:32 PM

If you're certain the leak is at the valve, pull it off and look at it. It's likely not serviceable, but you may at least be able to inspect the piston or diaphragm inside. It may have electronic actuation, but it's innards should still be of a traditional, mechanical design.

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SRT82ECOBOOST · July 30, 2014, 11:22:11 AM

So I tested both BOV's my making them VTA and they are both dumping boost under WOT. I can actually make the car excellent rather well by only taking the throttle to about 30-50% and at that point the vehicle will hold boost. I have verified with the Torque that with the stock tune is making 12-13psi of boost. Not exactly sure what is going on, but hopefully someone can weigh in on this.

wasinger3000 · July 30, 2014, 11:58:33 AM

You need to view the desired boost vs actual boost as well as actual waste gate vs commanded. That's the only way you will know if one of the BOV's is failing. That way you have factual data to compare. Just listening to it won't be enough.

The only simple/quick thing I can think to do is have someone in the car, apply parking brake, put the car in gear, do a standing brake boost to full throttle while you hold your hand by the BOV to see how much boost is being dumped compared to the front bov.