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High idle after intake replacement,need help quick

christopher8911

christopher8911

New member
I have a 98 GP GT with the 3800. Car ran great but had an issue with the lower intake leaking onto the block, so I decided to do the intake replacement. I ordered the "gm shure fix" upper composite intake, gm lower aluminum intale gasket set, new fuel injector seals, new 180 thermostat w/seals, and new heat senser. Install wasn't difficult at all and all bolts were installed as directed per instructions. After I finished installation I drained and changed radiator fluid, and engine oil. When I started the engine the car shot up to 3000 rpm then rested at idle around 1200 rpm. Engine stays reved. I can press the accelerator and the car will take the gas, it just seems to be ideled up high. Everything was cleaned and install was as instructed. I did clean the throttle body before I re-installed it to the new intake. No codes are being shown and im not shure what i should do to try to fix the problem. Any ideas?
 


I re-installed all parts that were removed with new parts with the exception of the small plastic elbow that connects the lower intake manifold to the heater coil lines. That shouldnt cause the problem should it? Im thinking it has got to be something with the throttle body or the upper intake but im not shure.
 
Ok today the ses light came on and advised it was the iac module, bad iac connection, dirty throttle body, or engine vaccume leak. I replaced the IAC valve and replaced the vaccume hose that runs from the side of the throttle body to the module mounted next to the fuel rail in hopes to fix the problem, no luck. The throttle body was cleaned when i pulled the intake. The car drives fine, accelerates well, doesnt run rough, it just idles way too high. On start up the engine revs to 2300 rpm the soon settles to 1400 rpm. When placed in gear the engine drops to 1000 rpm without a/c running. With a/c the car idles at 900 rpm in gear. I also noticed that when i pull the oil stick out there is a strong vaccume coming from the dipstick opening. If you remove the oil cap the engine will shut off. I dont know what to do. HELP.
 


good work. when that is plugged up it makes the car run retarded funny because of the excessive crank case pressure that builds up.
 
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