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Old 06-12-2006, 02:52 PM   #1
Scooby Newbie
Member#: 84841
Join Date: Apr 2005
Location: Raleigh, Durham Area, NC
2010 WRX

Default vf30 cobb 2.5 boost

OK, i have a VF30 and am running the stage 2.5 VF30 map from cobb on my 05 rex. The most boost I can ever hit is .09 on the stock gauge, I dont know what the problem is, I dont think im just imagining things because I could swear at stage 2 a few months ago i boosted significantly over .1 . Also, this did not start when I installed the VF30, it was happening with the stage 2 map as well. If this helps, I notice a sort of blowing/whoosh sound coming from somewhere at all rpms, whether it is idling or accelerating or what. I also hear a ticking/clicking coming from the downpipe area of the engine. Any ideas?
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Old 06-12-2006, 10:03 PM   #2
Scooby Specialist
Member#: 73884
Join Date: Nov 2004
Chapter/Region: HIIC
Location: Honolulu
16 HyperBlue STi
16 Crystal White STI


Since you had to pull the intercooler and many connections off when you did the turbo swap, the possibility of a leak before and after is possible. A leak prior to the swap might have gotten fixed only to have a different one show up when you put everything back together. Have you gone back and checked the tightness of all the bolts? If there is a leak before the turbo, you should be able to see some blackening around the area of the leak. If there is a leak after the turbo on the exhaust side, it will not give low boost. If there is a leak after the turbo on the compressor side, you will have a situation like what you are experiencing. Check the Y-pipe to the intercooler and the throttle body coupler. Also, if your wastegate solenoid has a problem with the hoses, your boost will be off. Did you use the stock turbo wastegate hoses? The hose with the brass restrictor goes on the compressor outlet side of the T to the wastegate and solenoid. If that brass restrictor is placed on the wastegate side of the T, you will have low boost.

The vf30 wastegate hoses are not compatable with AP mapping. I know this for two reasons. First, when I went stage 2.5 I tried it with the vf30 hoses first and things were horrible. Second, I have ST now and have since sold the stock turbo with the stock hoses. I put the vf30 hoses back on and began retuning my turbo maps for the vf30 hoses. Wastegate solenoid duty cycle was dramatically different with the vf30 hoses. The stock turbo hoses needed about 80-90% duty cycle to hit 18.5#, the vf30 hoses used about 40-45% duty cycle to hit 18.5#.
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Old 06-15-2006, 03:03 AM   #3
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Join Date: May 2002

i would say check the wastegate hoses. also, check the brass restrictor pill. that's the only thing i can think of at this point.
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