Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

Then, with the throttle at idle position (the spring forces it there), you
carefully turn the switch until it goes "click". Tighten the two screws. Be
sure, as you rotate the throttle (TB still in your hands) you can clearly
hear the switch "click" and that it does it while the arm is maybe 0.030" off
the setscrew.
Notes on Idle Speed Adjustments [Gregg Stade]:
[Adjustment of Pre-89 TB, TPS and Base Idle:] The p/n's for the
gaskets you will need are 1271488 and 463766. There is an o-ring
on the black knob (pre-'89 only) that you will have to remove to
thoroughly clean the housing p/n 947114. Do not remove the
throttle cable, but with a small screwdriver unclip the small plastic
linkage lock from the throttle body and swing it up , then
disconnect the throttle switch . After the housing has been cleaned
the throttle stop is adjusted. Loosen the 8mm lock nut and back out
the screw, turn the screw back in just till it contacts the lever.
Rotate the screw another 90 degrees and lock it down. Install the
throttle switch and rotate it till it clicks with the throttle plate closed.
Lock it down, the switch should make a click as soon as the throttle
plate is moved . Test it several times in your hand at varying
opening speeds make any fine adjustments now. BTW don't loose
the o-ring on the switch if you remove it; it is not available as a
spare part. With the housing back on the car, adjust the linkage
rod so that the throttle plate doesn't move when it is hooked back
up. After everything is hooked back up there are two more things
to do. First, adjust the cable with the threaded piece at the throttle
bobbin. You just want a little slack. Second, base idle has to be
reset. (Pre-1989 only:) For this, you will need a tach/dwell meter.
You need to read engine rpm. Warm the engine to operating temp.
Here s the tricky part. There is a blue connector behind the battery
with nothing plugged into it . There should be a blue/white wire in
the connector. Ground this wire it shuts off the idle speed motor so
that base idle can be adjusted with the black knob on the throttle
housing. Base idle for this car should be 700 rpm. When the
ground lead is disconnected the idle should go up to 750rpm's +/-
20 rpm's.
[More on Setting Base Idle Rate:] Just adjusting the base idle by
the set screw is not a good idea. First, you must check to make
sure the throttle housing is clean from oil deposits, as above.
Upon re-assembly, the base idle set screw must be backed off,
then turned in till it just touches the housing. You want to turn the