Shop IDLE SETTING 944 T
Setting the Idle on the 944 TurboTo do it correctly and thoroughly is a four step process.
Step 1 - Setting the hard stop
This is performed while the car is not running. The purpose of the hard stop adjustment is to keep the throttle plate from binding or landing in the throttle body bore too hard. It's purpose is "not" to set the idle speed. Loosen the jam nut (8mm). Loosen the screw with a small straight blade screwdriver slowly and carefully until the screw turns loose. With a gentle touch, slowly turn the screw back in until you can feel it touch the stop. From there, turn it another 1/8 turn. Tighten the lock nut back down. If you have the intercooler pipe off, you would barely be able to detect that the throttle plate moved.
Step 2 - Setting the Throttle Position Sensor (TPS)
Car is still not running. A correctly adjusted throttle position sensor will make a clicking sound when you just roll the throttle off the stop. Place your fingers on the throttle cam and rotate the throttle open off idle. If it does not click, it's not adjusted properly. If it rotates several degrees before clicking, it's not adjusted properly. Loosen the two Phillip screws on the TPS just enough to allow you to rotate it with a slight effort. Rotate the TPS to where when you rotate the throttle cam, it clicks when you're just off the stop or about 1 degree of rotation. Then tighten the two TPS screws back down.
Step 3 - Jumping the Idle Stabilizer
Car is still not running. You will need a short piece of wire (3-4") with both ends stripped bare. Place the ends of the wire in the terminals "B" and "C" pictured below. This will put the Idle Stabilizer in a central position of it's movement when the car is running.
Step 4 - Adjusting the idle RPM
With the previous three steps completed, you will be setting the idle RPM. With the car in neutral and the emergency brake on, start the car. Turn off the A/C if on. Let the car come up to normal operating temperature. The idle RPM is adjusted by turning the idle screw located on the top of the throttle body. Normally it will be approximately 1/2 turn open from fully seated down (clockwise). Idle should be 840 +/-20 RPM.