boost problems and fuel cut at wot

[red21t]

I have searched, searched and searched again, i have read the similar threads, but nothing is helping me..... i have a 99 gst 5spd, i was driving to work and no problems, i could get on her at wot at 14/15(innaccurate boost gauge) psi no problem, the boost would hold and everything just worked, well i came to train track slowed down for it then proceeded to take off in second, once it boosted up to 14/15 psi at wot the car made a horrid flutter noise kind of like a helicopter, and it bogged down in power, so after shi*tting my pants i let off the gas and i pushed down the gas peddle at normal acceleration and making sure it didnt boost, it got up to speed with no weird noises or shudders. So after work i tested the driving of the car, and i came up with this, I am able to boost up to about 10-12 psi if i do NOT have the car at WOT with nothing wierd happening, and if i have the car at wot, the second it hits the set boost level (14/15 psi) it makes the shudder sound and bogs down, so i decided to turn the boost down and im guessing that i set it at about 12 psi and tested the car at WOT and this time i watched my boost gauge, as soon as the car hit 12 psi and bogged down the boost gauge jumped to 15psi and then dropped down to 12 psi WTF, I apologize if this is a commonly answered problem and is posted already, and i apoligize for this long article about my problem, ANY help is greatly appreciated. I am new to DSM's and have little knowledge about them.

 

[white90gsx]

Are you sure your only boosting 15psi?...Is it a stock turbo?

 

[red21t]

Stock turbo, stock 2g plastic bov , and the boost gauge read at about 15 psi, and there is a mbc on the car, came with it, unsure of brand, i try not to mess with it,

 

[white90gsx]

Your stock bov aint holding the boost I had the same problem on my 2g. Those plastic bovs are junk...Time to upgrade...

 

[red21t]

thats what i was thinking but like i said i had no idea, thanks for the help

 

[white90gsx]

Yea man no problem..Unless you have a bad boost leak..Did you test for any leaks?...When I would boost and would leak it would do that.

 

[red21t]

i have not tested for leaks, i didnt think that it could be a boost leak problem because im still getting gained power when i boost it up and it will hold a boost just as long as i dont have it at wot with the boost at like 12-15 psi, and its 20 degrees outside and i do not have a heated shop to work in.

 

[xsboost]

As you already know check your BOV. The stock plastic bov is crappy and can fail pretty easy. If it cracks or the diaphragm tears (what happened to mine) it can make a "flutter" noise. It can also make the same noise if the boost/vacuum line going from the manifold to the bov is split, torn, crimped, clogged, or not hooked up. Also do the boost leak test. If you have a boost leak, even a tiny one, you're gauge could read 1 thing but the turbo could be working hard enough to make a lot more boost in order to reach the required boost level to open the wastegate. If the turbo works too hard (especially an aged T25) it can over run the bearings causing a "flutter" noise.

 

[red21t]

As you already know check your BOV. The stock plastic bov is crappy and can fail pretty easy. If it cracks or the diaphragm tears (what happened to mine) it can make a "flutter" noise. If the turbo works too hard (especially an aged T25) it can over run the bearings causing a "flutter" noise.

The first part makes sense as it is really cold here(if that has any effect), i just replaced the turbo with a rebuilt never used t25 from xsboost turbochargers, i could not afford anything as far as an upgraded turbo.

So i guess i will be nice to my car until i can get my hands on a 1g bov, i dont plan on anything for this car except for selling it once spring comes...so i should be good until then if that fixes the problem. Thanks for the advice and knowledge

 

[xsboost]

Good luck. Let us know what happens.

 

[Jimmer307]

Spark plugs and wires did it for me. I had the same exact problem you are describing. When you have a boost leak it is more constant, sounds like your plugs and wires. Even though you should definately replace that piece of shit stock bov, do the plugs and wires first. If it was a boost leak, it wouldnt' matter if it were WOT or gradual, it would stutter reguardless. Let me know if it works out for you.

 

[habitatguy187]

If it was a boost leak, it wouldnt' matter if it were WOT or gradual, it would stutter reguardless.

This isn't always true. I have a boost leak in my throttle body shaft seals and if I don't WOT it I can boost w/out hitting fuel cut, but once I open it all the way up, Bam, fuel cut. This is because the shaft seals change positions as you depress the gas pedal.

 

[red21t]

hey guys thanks for all the suggestions turns out it was just plugs and wires...... crazy never would of guessed, but i guess thats what i should expect with a dsm

 

[Jimmer307]

Damn Staight son... That was the same exact problem i had... Keep it running straight up,