09ctc

I got my cousin a Hahn racecraft blow off valve for Christmas. We haven't installed it yet. His upgrades are the cold air intake, intercooler, the turbo back exhaust, and a trifecta tune. All parts from Hahn Racecraft. He has 2.5 bar map sensors. I just want to know if anything bad is going to happen with installing this blow off valve because from reading other threads I'm worried that this is a waste of money because I would hate that. I don't want to hurt the car in any way. He has the LNF by the way. Thank you for taking the time to read this.

footballplaya3k

iTrader: (1)

Yes, it is a total waste of money on a stock turbo car.

You will run into lots of issues trying to drive the car without a tune. You also need a new lower charge pipe that allows MAF relocation, a MAF extension harness, a BPV block plate, and a new tune.

09ctc

The car does have a trifecta tune, i did purchase the plate. The car has the relocate and charge air piping

09ctc

The car is not stock, please read my entire post, thank you. It has all the information I thought is needed

tuned08ss

U just need a retune. But it will be a pain

09ctc

Now when you say retune, do you mean on a dyno?

nathan112i

data logging on the road works fine, so the car currently has the maf relocated from pre turbo to after the intercooler?

09ctc

Yes

nathan112i

yup as long as you are running a blow though maf setup and get the car tuned you should be golden

kzak104

iTrader: (1)

i think trifecta has a mafless tune available now,

footballplaya3k

iTrader: (1)

Where does your post say the car has lower charge piping, MAF relocation, and a BPV block plate? Try reading again yourself, bro.

footballplaya3k

iTrader: (1)

I ran it and it sucks dick. I recommend it to no one.

09ctc

I still don't understand why you need a tune for a blow off valve. I own a Jeep haha the Cobalt is my cousin's car. Can you guys please explain it to me? I thought it is just a valve that releases boost pressure when shifting so the charged air doesnt go back into the turbocharger making that "cha cha cha cha cha," and also making you be able to shift at a slightly higher boost pressure in between shifts to reach your top boost pressure. I'm sorry for not understanding, I hope you guys can explain it better than what I think it does.

09ctc

I'm sorry about that information. But you said the car was stock. Hense that's why I told you to read the complete post.

nathan112i

you need a tune for a blow off valve because the stock bypass valve does not dump the extra air into the atmosphere it recirculates it. if you dump air into atmosphere with out relocating the MAF and getting tuned every time your blowoff valve vents the car will go super rich because the MAF thinks the engine will receive X-amount of air and your car will fuel to desired A/F. when you dump all that extra air out the car doesnt know and is still fueling like crazy making it run rich

09ctc

What is the difference between the atmospheric and recirculating BOV.

tomj77

iTrader: (2)

if u are gonna tune for the bov do not use trifectas tune, its awful. get hp tuned by a good tuner.

Shanedude

I'm running the ECP tune but only for about 20,000km. Goes rich and makes an exhaust pop sometimes, GMS1 did the same but not as often.

footballplaya3k

iTrader: (1)

I said a stock turbo car. That means the car has the turbo it came from the factory with.

09CobaltSS1

First off, the Hahn bov is just a relabeled Turbosmart Veeport bov. Complete cheap junk imo, however is still somehow over priced by Hahn.. lol.

Second, they leak incessantly. Due to this, even with a maf relocate, you will still have the good chance of the car going into limp mode and/or a P0101 DTC.

Third, a car like a cobalt doesn't so much need to be "tuned" for a vta bov. That's absolute bunk, and don't let anyone convince you otherwise. There are far too many variables involved to accurately do this on ANY draw through maf vehicle. Which is really pretty much every auto maker (short of Hyundai and Dodge who use what is called speed density for fueling and load calcs). Any vehicle equipped with a maf uses those flow readings over the maf to calculate fueling and other factors for the engine. Some of the calculations are interpolations and even "assumptions" by the ecm. With all these factors involved, when a vta bov dumps excess boost pressure anywhere other than back through the intake stream (aka recirc), this throws the ecm into a tizzy. As a result, it will rich spike and mostly assume there is some sort of leak occurring and force the ecm into limp mode and/or throw a DTC.

With all that said, this is why a maf relocate is very important. THIS is the only true way as a tuner to have full control over what is happening with a vta style bov. Also, this allows the end user to adjust (assuming an adjustable bov is being used) the internal pressure rate inside the bov, to better adjust the pressure release for varying reasons.