Major boost creep, open exhaust, working wastegate... HELP!

[allezgrand]

My boost is holding steady at 12 PSI from 3k to 5k rpms, but when I get to 5k, it creeps rapidly to 20 PSI. My exhaust is completely open at the O2 housing. I put pressure to the actuator and it opens when it should. I even compared it to my old turbo, and they both open at the same pressure. I am completely at a loss. I'm happy to hear any suggestions. The turbo is a Big 16g btw.

 

[fwdtsi]

Try jacking the boost up to 16 or 17 psi it probably wont spike like that.

 

[allezgrand]

I can't do that, I have still have a factory fuel system and I don't have a MBC.
Any other suggestions?

 

[fwdtsi]

I would get an MBC of ebay for 10-15 dollars then. when your trying to run low boost it will creep like that on a big exhaust system I would go ahead a but a exhaust on it actually I have a downpipe with a muffler welded on you should try that

 

[allezgrand]

That doesn't seem right... I am not the first person to put on a Big 16g and run it at stock boost, and I have not heard of others having this problem with too large of an exhaust system

 

[jezefink]

i had the same problem..a few days ago...even with my mbc it still creeped past 20.....i run a gm maf setup..and was running an open turbo w. screen and i didnt have creep...i put on a custom inlet...and it started creeping...i think the inlet was blocking the wg actuator....that might be your problem..

 

[DJ23GSX]

i don't know if this will help you but since i put on my 3" intake pipe and 3" turboback exhaust i creep like crazy too. Its a ported 16g with a 34mm flapper on it and it creeps up to about 20psi also. I might try and put the silencer back in behind the MAF and see if that will help stop the turbo from sucking in so much air that easily. I've been battling this problem for a few months and can't seem to get past it. I've got a line running straight from the turbo outlet to the wastegate actuator and that still don't help.

 

[jfdid]

Port the wastegate!! The wastegate isn't bypassing enough air away from the turbine because the hole isn't large enough. Grind the space behind the flapper so it can open more and possible by a new flapper(bigger) and port the hole as well. It's a pain to remove everything again, but it probably has to be done, or you need an exhaust.

 

[allezgrand]

Originally posted by jfdid
or you need an exhaust. [/B]

I had somebody else mention to me today that with too little restriction on the exhaust with a 16g or larger, it will creep.
My factory exhaust had broken at the flex pipe and was wide open and when it started creeping, I opened it up totally by removing the down pipe.
Solution:
I put the downpipe back on and hammered the opening in the end half way shut so that it would create more resistance. Problem solved. It creeps from 11 psi to 12 psi now...sometimes 13 if I'm on the throttle for a while in a high gear at high rpms.

DJ23GSX: If you want the cheepest solution, I would say shove a small piece of sheet metal in the exhaust between one of the couplings or something in order to create some resistance until you can afford a fuel pump and injectors, or do as you said with the MAF. Just a thought.

 

[DJ23GSX]

Well i put in the MAF silencer today and it helped quite a bit. Boost only creeps to 15-16psi now instead of 20psi. I bet if i put the restrictor back in the muffler it would cut the creep a few more psi.