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Old 08-12-2013, 07:08 PM   #550
prisky
Scooby Newbie
 
Member#: 365221
Join Date: Aug 2013
Location: Sacramento
Vehicle:
2002 WRX
Silver

Default 2002 WRX stock bare nipple vacuum leak on intake manifold

Came in here to post what worked for me.

2002 WRX bone stock. After a hard pull I noticed a very rough idle at a stoplight. Immediately after idling I got a CEL. Pulled it into the garage and as I turned the car off I heard a soft whistle coming from the engine bay. It had to be a vacuum leak.

CEL codes: p0171, p0301, p0302, p0303, p0304. Waited for the car to cool down and I sprayed along the intake, vacuum hoses and around the intake manifold with carb cleaner. No noticeable change in RPM. No rips in the turbo inlet hose. I found a very brittle boost solenoid hose coming from the T-fitting off the turbo and upon touching it, the thing broke. I replaced it with a hose with a similar internal diameter (uncertain if I should find a OEM hose with coupler or keep it) and cleared the CEL with my scanner. Rough idle still remained and after 10 miles of driving all codes resurfaced.

Waited for the car to cool for a few more hours to check the intercooler Y-hose and bypass valve hose recirc for rips or tears. As I pulled off the intercooler I noticed a bare nipple on the intake manifold (slightly to the right and underneath of the BPV). I shined my flashlight around the engine bay to look for a disconnected hose and found a small black cap for the nipple. Capped the bare nip, reconnected the intercooler and reset the CEL.

The car idles smooth now and CEL hasnt resurfaced for 50 miles. This thread saved me! Thanks to CirrusWRX and PaWRX for compiling a roadmap of solutions to try. This thread has been going for a decade and is still helping folks like me out. Hopefully this will help someone with a similar situation.
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