whats causing this high boost?

[Sandman817]

Alright guys, let me start off by saying i have a 99 gst. It has a big 16g turbo installed on it, k+n clamp on filter, o2 housing w/ dump tube, and 3" open downpipe. Before i had the downpipe and o2 housing installed, i was running waste gate pressure @ 10PSI since my MBC was acting up on me. I never touched the WGA during the install. So i finished up installing everything last night and took it out for a drive. I went WOT and hit 10psi, and then it kept boosting until 20psi and i started hitting fuel cut. I'm not sure why its boosting so high....should i go back and adjust the actuator for less boost? Let me know, trying to get this thing running good

 

[viperlp01]

If your only running the waste gate and no mbc make sure that the wastegate is seeing a good boost source and make sure during the install that you didn't accidently pull the hose off.

Is it an ebay 16g with the adjustable wastegate arm? If so you need to re-adjust the arm since they come rediculously tight from china. Pull the arm off the wastegate flapper and spin the arm out until you have to pull just alittle bit to get it on the flapper arm.

 

[rock1t]

never heard of too much boost.

what are you using as tuning software? are your vacuum lines still attached and nothing popped off from working in the bay?

also fuel cut is bad. do you have a wideband?

 

[Sandman817]

yes i know fuel cut is bad, and no everything was connected and still is. I had this problem when i initially test drove my car after the 16g install and i ended up backing out the wga arm since it was boosting till 20psi and hitting fuel cut.

I know backing out the wga arm lowers boost, but won't this create more lag since the exhaust gases are escaping due to the flapper being loose?

My o2 housing dump pushes out some exhaust at idle so i am not sure if this is a problem or not.

As far as tuning software, i am running factory ecu with no tuning now. I just want to run 10psi as a DD for now untill i get more money for ecmlink, injectors and FP.


Well....#### my life. the motor started knocking again after i replaced all the connecting rod bearings in it due to cyl 3 bearing went out on me a couple weeks ago. I think the motor may have walked on me since i was driving and pushed the clutch in and was coasting and it just died on me, put it back into gear and bump started it. Gave it some gas and it wasn't going anywhere.

 

[viprez586]

It's called Boost Creep and it's because your running a 3" downpipe.

 

[Sandman817]

well it doesn't even matter now since the motor is done. started knocking again after i replaced all the bearings

 

[viprez586]

Probably cause you hit fuel cut/leaned out one too many times.

 

[Sandman817]

how do you figure that is the cause, and not the fact that the motor has 134k on it

 

[95gst16g]

Sucks to hear about the motor I guess my advise won't do any good. But I was gunna say check the vacume lines to the wastegate and make sure they have no holes,came off,etc. It could also very well have been boost creep the 16g is notorious for it ecpecially with a open exhaust like that.

 

[Sandman817]

well from what i've ready, the dump tube is supposed to eliminate the boost spike

 

[Redwidow]

well from what i've ready, the dump tube is supposed to eliminate the boost spike

Yea with an external dump it eliminates creep.

 

[rock1t]

how do you figure that is the cause, and not the fact that the motor has 134k on it

because you are flowing a lot more air into your motor, and not getting adequate fuel. even though you are trying to stay around 10lbs, that's the amount of pressure, not the volume of air going into your motor. that's why 20lbs is different between a 16g and a holset hx40

 

[viprez586]

Please read the definition between boost spike and boost creep, and you'll understand OP.

 

[Sandman817]

So what would be the best idea to help decrease the boost creep? Im running a new o2 housing with an external dump tube, 2.75" to 3" downpipe, and the big 16g turbo.