Boost Question

[talontsi01]

I got a quick question. Its about my turbo. I'm running 15 psi right now. When i start my car, my boost gauge shows -15 (15 vacuum). It's when I push in the clutch, the boost goes down to -20. When i let off the clutch and floor the gas, the boost gauge reads up to about 10 psi at most. When i push in the clutch to shift into second, the boost reads back down to -20, where it should be -15. It does this when i shift for all of the gauges. For each gear, starting with first, the boost increases better and better. First gear is the worst. Second is a little better. Third is fine...and it keeps getting better. But first gear is so bad that I almost dont even get boost most of the time unless i floor the gas pedal 100%. I hope someone can tell me whats wrong.

thanks

 

[nine5raptor]

doesn't really sound like a problem to me. what are you reading (boost wise) above 4000 rpm in 3rd gear @WOT?

btw. my idle incurs ~18 in. Hg and engine braking is c. 22 in. Hg

 

[talontsi01]

3rd gear - it will go up to 15 psi.

its first gear that im worried about. i can only get to about 8 psi or maybe 10 psi if i slam the pedal.

also, if im running 15 psi, my boost gauge should read -15 when its idling. correct?

 

[CH152]

Sounds like its creeping in the later gears.. what is you MBC set at or you not have one? I'd say its time to get out the die grinder and carbide bits to fix that or help it. Invest yourself in a MBC. Like on mine before porting... I would run about 15 psi in 2nd and 3rd then creep to 19. Now it hits 19 and then falls down after 5500 in first and second, then in 3rd-5th runs up to 19psi and holds then creeps damn slowly up to 20 then falls down to 19 again. This is in cold weather though

 

[nellystyle]

the -15 is vacuum not boost, so if you're running 15 psi then when you are WOT it will be on the +15 side.

mine is all stock except the gauge right now and i get 12-13psi at WOT in 3rd and when i'm idling i'm ~16 in vac and when i'm letting the gears slow me down (in gear foot off gas or braking) i'm typically 20-20 in vac, hope this helps

 

[nine5raptor]

Originally posted by talontsi01
3rd gear - it will go up to 15 psi.

its first gear that im worried about. i can only get to about 8 psi or maybe 10 psi if i slam the pedal.

also, if im running 15 psi, my boost gauge should read -15 when its idling. correct?

the boost level has nothing to do with the vaccuum when idling.

 

[talontsi01]

It wasnt like it is now. Before i was running 15 psi and thats what i got. It idled at 15 vacuum. and at WOT, it went up to 15 psi like it should. now, it only gets up to about 8 psi at WOT (only in first gear).

also, i had my exhaust checked out toady. there is a exhaust leak were my straight pipe comes into the pipe that runs to the muffler. the leak will be fixed soon, but do you think this boost problem could have something to do with the exhaust leak?

thanks

 

[CH152]

no, if anything that exhaut leak where you are talking about will open it up like the smallest fraction.. and give you probably .0003 more psi there. :laugh:

 

[T2514.07Spyder]

have you checked for boost leaks?Are you using an aftermarket BOV? If you are using a turbo xs bov, then open it and make sure that the chamber is clear and that it is closed completely. If it isnt then you have to oil it, they get stuck. Also, have you checked the line that goes to the boost gauge? If it feels normal when driving but dosent look normal on the gauge then you probably have a defective gauge or a hole in the line. Good luck.

 

[talontsi01]

I dont have an aftermarket BOV. Is there a way to check my stock one? Also, my car does actaully "feel" slower in first gear and slightly in second. All of the other gears are fine. It's weird. I really dont know what it is.

 

[~laser_craver~]

Wut is the max boost ur gettin out of it?

 

[DrivnMastr]

THis sounds like a case of turbo lag do you have a large front mount rember turbos are not instant boost like a SC the have something called spool up time what turbo is on your car?

 

[wannabeboostin]

this is talontsi01 - i dont get the correct boost in first gear period. even at wot, im only getting about 2-3 psi. im running 15 psi.