what the hell is happening?.... car is stumbling...

i dont think it's boost leak cuz i just got my greddy type s installed and i listened for it but it doesnt sound like any boost leaking.... when i floor it at low speeds car stumbles. i look at boost gauge and it reads 17 psi and until it drops back down to 15 or so it stumbles..... it's the t25 so it shouldnt even get up to 17 psi.... is it fuel cut already? or is something wrong.

You cant hear boost leaks. You have to build the tester shown in the vfaq (10 bucks). At what rpm does it stumble? If its happening while you have boost, its almost always boost leak or ignition (plugs, gap, wires). And the T25 did over 20 psi on my car, I dont know where that misconception comes from. You should'nt run it over 17 psi if you want it to be efficient, but it will do it if you let it. I dont think a t25 at any boost pressure can hit fuel cut. I never hit it at least.

i had a similar problem with my car, although i have the stock turbo mine did the same thing whenever i would give it a lot of gas , it would stumble like it was running out of gas or something , i changed the plugs and the wires and checked the gaps and it works perfect now , i run about 13 psi with no problems , so i would say give that a shot. Hope that helps

I'm hearing this a lot recently, and I'm planning on changing my plugs first, then wires, both next week some time. I COULD do it right now, but I was going to wait a while since it's not a big problem for me (stay off throttle) and get some school credit for doing it in auto class.

Its stumbling cause you have a rich spot. Its normal to have boost drop at high RPMs cause the turbo runs outta steam. Take the car to a dyno and tune it. Do you have a diverter valve or BOV thats vents into atmosphere? If you have a BOV that vents to atmosphere get rid of it and go back to a diverter valve. I say this for 2 reasons. 1) atmospheric BOV creates a sudden lean spot when it vents which can create severe detonation. 2). Diverter valve allows the turbo to recover quicker so you get on boost sooner which means more power sooner and also its alot easier to tune. you dont need a atmospheric BOV unless you have a huge turbo making a shit load of boost quickly and have to vent it to prevent overboost.

Just a few touch ups to that post. When the BOV vents you will have a momentary RICH condition, not lean. The need to go to a larger BOV is not to prevent overboost, but to keep the turbo more spooled between gears (more like underboost ;) ). With very large turbos you have no choice but to run a large valve that doesnt have provisions for recirculation, like a SARD or TIAL. The car will run like ass vented, even though I did it for years with some success. You are right, it is a lot easier to tune with it dumped back in. I have since switched to a blow through hot wire MAF, so I can vent with no problem whatsoever. But on the stock MAS, keep it recirculated.