I just replaced the intake manifold on my 2001 galant now it idles very high i dont know why

o2 sencer

High idle is usually caused by a vacume leak. First place to check is the cold air intake manifold. All hoses, throttle body, and sensors. Throttle Position(TPS), Mass Airflow(MAS), Idle Air Control Motor (valve) IAC. Controls Idle speed

A malfunctioning throttle system can cause both a high idle as well as an engine stall.

A dirty air intake or cracked air intake tube is often the culprit.

How to Fix an Engine High Idle in Under 15 Minutes

This is a typical vacuum leak. Check all the hoses. If none are sucking air then use WD40 and spray around the intake manifold. If the engine runs better or changes how it runs then look at replacing the intake manifold gasket.

check moter and switch wichever is bad replace

you shouldnt have to remove the manifold. you can access those plugs by removing the front tire and go in that way.

Clean your fast idle thermo valve (fitv) if that dont Work try cleaning idle Air control valve (iacv) you can go to google images to see where they are located on the intake manifold if you dont know And also if you dont know you can search google on how to clean these parts. Slightly dirty fitv was my problem cleaned it no prob. Since.

High idle
Changed IAC still the same, shown on scanner IAC 50-60 %, if it set to 40% the Idle is ok. What cause the PCM to set IAC too high? Is any one know?

LOOK AROUND THE AIR INTAKE HOSE.MAKE SURE IT IS INTACT NOT LOOSE.CHECK ALL VACUUM HOSES ON INTAKE.MAKE SURE THEY ARE IN PLACE.

Here is the common cause of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Her is a picture of the idle control valve,http://www.autopartswarehouse.com/mmp/nissan~maxima~idle_control_valve~parts.html it located on the intake manifold near the throttle body opening. Good Luck and Thanks for using FIX YA