So, today we turn the Boost up to 25 Lbs....(finally) and this **** is screaming out loud, takes off so hard in 3rd gear i gotta hold on to the shift knob hard..lol...but, yea there's always a but!! As soon as your going to shift from 2nd to 3rd or 3rd to 4th all the Boost is lost and the car has to work itself right back up. I remember there was someone else here having this same problem's but I can't find hes thread now.

Any Idea's? O yea, I'm going to the dyno soon.

 

First off, i'm guessing this is not a k04. What turbo would help. i'm guessing the wastegate is staying open and not letting you boost right after. Could possibly be a tuning issue.

 

Treadstone stage 4- 5557E Turbo. The tune is fine and the car is not giving any codes.

 

I'm gonna assume you have a MAF relocate and a BOV that is vent to air. If so, you are letting out all the boost every time you shift. That means the turbo has to build it back up. That's why I like recirc systems. Don't have to worry about that.

 

I though HP tuners already take's care of the relocation of the Maf allowing you to use an vent/air Bov.?

 

Shift faster!

 

Any vta bov is gonna cause serious lag between shifts. Its letting out air volume that the turbo has to build back up. It shouldn't be THAT bad but it's noticeable.

Its possible your tuner may have your ramp a bit slow too I guess but I am no tuner so hopefully one will chime in.

 

Also, do you not have your MAF relocated and are using a vta bov?

 

Naa it is relocated....

 

This is how its setup- Turbo->BoV->Intercooler->Maf->Throttle Body....so as long as the Maf is at the end it docent matter what the Bov does!! Its how it was explain to me. So, maybe the wastegate is sticking open?

 

Well sorta... It doesn't matter in the sense that you're not blowing off metered air which you would be doing if it was a draw through MAF setup.

The issue is that since you are blowing off air, the air that would normally get recirculated in a stock-like setup, has to be replaced before the engine will see boost.

Think of it like this... Since the blow off valve is spitting out air every shift, the turbo has to do that much more work to replace that air. That extra work = a delay in building boost.

The thing is, it shouldn't be so bad that it makes your car super slow but you will be a little bit faster if you had a draw through setup and recirculated the blow off valve.

 

"BOV Theory-
Theory
The function of a blow off valve (BOV) is to reduce pressure waves that result when the throttle plate of your engine is suddenly closed. For example, when shifting gears the turbo is still pressurizing the intake piping but without a bov to release this building pressure and with the throttle closed, the air can surge backwards and over time damage the compressor on the turbo. A blow off valve is designed to alleviate this strain by detecting pressure differences in the boosted piping (intercooler piping) and opening up a relief valve that either redirects the air to the non pressurized intake (turbo intake) or to the atmosphere.
The atmospherically vented blow off valve simply dumps the excess, vented air to the atmosphere. Since the BOV will reside on either the hot or cold pipe of your turbo system, venting to the atmosphere can cause problems for cars that are equipped with MAF (Mass Air Flow) sensors in the non pressurized intake. When the BOV actuates, air that has been measured by the MAF is dumped and is no longer present in the intake track. Since the ECU has no way of measuring this reduction in air, it still injects the same amount of fuel into the motor that was calculated by reading the signal from the MAF and therefore, the car will run rich. This will cause the motor to bog after shifts. To negate this issue, a blow off valve’s outlet must be recirculated into the non pressurized intake, after the MAF and before the turbo. This allows the excess air to return to the system, keeping the air fuel ratio in check.
Alternately, switching to a blow-thru MAF will allow cars with MAFs to vent atmospherically. A blow-thru MAF is a MAF placed in the cold pipe of the system so that the MAF reads the air before it enters the throttle. By doing this the BOV can be placed on the hot pipe (before the MAF in the system) and it will no longer affect the reading the ECU gets from the MAF. Also, cars that run MAP (Manifold Absolute Pressure) sensors in the intake manifold generally have no issue venting to the atmosphere as they are not constrained by the air differences in the intake tract that the MAF system is." Source: Driftopia Tech Blog ť Blog Archive ť HKS SSQV Recirculated Blow Off Valve (BOV) Theory and Install

 

I give up.

 

Lol!!

 

Sounds normal like others have tried to explain, either shift faster or shift later...

 

o dam, lol.....


You telling me I need to change my Bov? not sure how to recirculate a turbosmart bov, it blows open in all directions......lol.....forgive my ignorance....haha

 

Fighting words lol

 

...okay since you seem genuinely confused...

Yes, you would need a different blow off valve that is able to be recirculated. You don't HAVE to but then you just need to deal with the bit of lag between shifts.

Just to be certain, make sure your tuner does't have your boost ramp on something afully slow. I dunno if you even have the ability to adjust the boost ramp with your setup but at least its something you could eliminate.

 

Ok Thanks.