How do you adjust idle speed
#2
Hitsquad Ninja
Rennlist Member
Rennlist Member
this was originally posted by user MHT back in june
Start with the screw and locknut on the throttle linkage, that is not an adjustment, it's a setting. Loosen the locknut and back off the screw, turn in the screw until it just touches the linkage, turn it in an additional 1/4 turn, lock it down with the nut. At this point check that the idle switch clicks as soon as you open the throttle, and that when you release the throttle that it clicks again. If it does not then you will need to adjust the switch until it operates correctly, or replace it if it can't be made to work. The second screw on the throttle body is the idle speed adjustment screw, in an early car, simply turn it until the car runs at approx 800 rpm. In a second gen. 944 you first need to bypass the idle stabilizer by bridging the contacts in the test connector in the left rear corner of the engine compartment, then set speed to 800 rpm or set it so that it does not change when you plug and unplug the bridge. The allen on the air flow meter effects air fuel mixture, it has the greatest effect at idle, you can get it in the neighborhood by ear, but to do it right you need an emissions analyzer. Disconnect the o2 sensor and adjust the screw until the engine runs smoothest. If you u have an analyzer measure the exhaust ahead of the cat. converter and set mixture to about .8% CO. You might try pulling the boot off the throttle body and cleaning the area around the throttle plate. Use some carb cleaner and an old toothbrush to make it as clean as possible, clean the bore and the throttle plate itself. Over time deposits build up around the plate and restrict airflow to the engine, idle stabilizer values are set based on the supposition that the engine is getting a certain amount of air through the throttle body, if you cut that off then the engine will not be getting enough to run correctly, especially when it is cold and requires more airflow than when warm.
Start with the screw and locknut on the throttle linkage, that is not an adjustment, it's a setting. Loosen the locknut and back off the screw, turn in the screw until it just touches the linkage, turn it in an additional 1/4 turn, lock it down with the nut. At this point check that the idle switch clicks as soon as you open the throttle, and that when you release the throttle that it clicks again. If it does not then you will need to adjust the switch until it operates correctly, or replace it if it can't be made to work. The second screw on the throttle body is the idle speed adjustment screw, in an early car, simply turn it until the car runs at approx 800 rpm. In a second gen. 944 you first need to bypass the idle stabilizer by bridging the contacts in the test connector in the left rear corner of the engine compartment, then set speed to 800 rpm or set it so that it does not change when you plug and unplug the bridge. The allen on the air flow meter effects air fuel mixture, it has the greatest effect at idle, you can get it in the neighborhood by ear, but to do it right you need an emissions analyzer. Disconnect the o2 sensor and adjust the screw until the engine runs smoothest. If you u have an analyzer measure the exhaust ahead of the cat. converter and set mixture to about .8% CO. You might try pulling the boot off the throttle body and cleaning the area around the throttle plate. Use some carb cleaner and an old toothbrush to make it as clean as possible, clean the bore and the throttle plate itself. Over time deposits build up around the plate and restrict airflow to the engine, idle stabilizer values are set based on the supposition that the engine is getting a certain amount of air through the throttle body, if you cut that off then the engine will not be getting enough to run correctly, especially when it is cold and requires more airflow than when warm.
#4
Three Wheelin'
Steve:
The idle adjustment is on the throttle body. Look for a slotted "screw." The only other adjustment on the throttle body is for the throttle plate mechanical stop. This is adjusted with a screw and lock nut.
To set the mechanical stop you need to remove the throttle body, loosen the screws for the throttle position switch, back out the mechanical stop, turn the stop screw until it just touches the stop arm, turn the stop screw in an additional 1/2 turn, and then tighten the lock nut.
To set the TPS, hold the throttle closed against the stop and set the switch so that the switch makes a soft "click" just as the throttle starts to open.
To set the idle speed, install the throttle body, connect a Dwell/Tach to the coil, start the engine and let it come up to temperature (Cooling fans cycle on and off). Adjust the idle screw for an engine idle of 850 +-50 RPM.
On the early cars idle is "set" mechanically. The only "automatic" idle compensation is a solenoid valve (mounted at the rear of the air box) that opens when the A/C is running.
Unless you are having fuel economy or emissions issues there should be no need to "tweak" the air flow meter.
The idle adjustment is on the throttle body. Look for a slotted "screw." The only other adjustment on the throttle body is for the throttle plate mechanical stop. This is adjusted with a screw and lock nut.
To set the mechanical stop you need to remove the throttle body, loosen the screws for the throttle position switch, back out the mechanical stop, turn the stop screw until it just touches the stop arm, turn the stop screw in an additional 1/2 turn, and then tighten the lock nut.
To set the TPS, hold the throttle closed against the stop and set the switch so that the switch makes a soft "click" just as the throttle starts to open.
To set the idle speed, install the throttle body, connect a Dwell/Tach to the coil, start the engine and let it come up to temperature (Cooling fans cycle on and off). Adjust the idle screw for an engine idle of 850 +-50 RPM.
On the early cars idle is "set" mechanically. The only "automatic" idle compensation is a solenoid valve (mounted at the rear of the air box) that opens when the A/C is running.
Unless you are having fuel economy or emissions issues there should be no need to "tweak" the air flow meter.