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Surge at idle

J

John Surrency

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"repowered a boat w/ a 97 5.7

"repowered a boat w/ a 97 5.7 GLI volvo. so far I replaced: plugs, wires, cap, rotor, ign coil & high pressure fuel pump. I began w/ the engine only running if I continued to spray fuel into throttle body.I've gotten it to start up & run but it surges at idle & Idles rough.If Iraise the idle slightly w/ throttle it seems fine, sometimes it hesitates ongiving throttle.Still seems like fuel restriction or vacuum issue. Have new tanks, fuel lines & filters but I did add racors to the system. Any pointers."
 
Also I originally replaced TBI

Also I originally replaced TBI injectors. Ive tried sraying poertune around throttle body & intake but someone told me I need to actually get starter fluid to check vacuum there.
 
i would plug it into a compute

i would plug it into a computer to see if the sensors are right and IAC valve is right
 
"Sounds like a large vacuum le

"Sounds like a large vacuum leak. That kind of leak would be audiable and up around the throttle body unit. I would use carb cleaner and spray around the base gasket, etc looking for fluctuations in the idle speed. Also look for unplugged hoses along the plenum. JIT is right as well. Plug in and look for diagnostic codes. A MAP sensor or TPS sensor unplugged would cause this."
 
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