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Intermittant Boost


Vehicle Information: Year: 1989; Engine (Size, Modifications): 3.3L Turbo; Total Mileage: 10500;

Hello,I hope you are well.I have recently purchased an '89 930 cab and for the most part love the car. The part that is not so lovable is an untermittant boost problem that I have. Whent he car is cold it develops boost. Sometimes I can drive the entire day and the boost is always there. Occasionally, it is not. The only repeatable symptom is that it works when first started for at leaset a short period of time. I have had the wastegate rebuilt and the popoff valve rebuilt but am not sure of the quality of the work. My belief is that it is good, the guy was recommended by people I have spoken with in the area PCA club and seems to do alot of work on race Porsches for people in my area. Anyway, can you help me understand what could lead to this type of problem? I am looking at possibly having him replace the wastegate or the turbo, both big bucks, but would prefer not to just swap out parts. Could the popoff be jamming open, or maybe the wastegate jamming open? What else should we check? Vacuum problem?Thanks very much.M

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