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I can think of three things that can keep the plate from fully closing. The most common is grime around the edge of the plate and corresponding area of the throat. The next most common is improper adjustment of the TPS, if the switch is rotated too far it will actually keep the plate open. And finally, the plate can bind if it's off center in the throat. If you don't see a fairly even ring of light around the plate when closed then the screws can be loosened and the plate adjusted. To loosen the brass screws pinch in the split ends and be careful not to damage the screw head with the screwdriver (rather than spreading the ends back out, simply cut them off in place, file smooth, remove and re-install with a drop of locking compound)
After cleaning, you will want to check/adjust the throttle stop screw, TPS and throttle body linkage (the click-click test). There are basic procedures described in the FAQ, but for more precise adjustment of B230 engine throttle bodies proceed as follows (based on a 1991 Volvo TSB update to the service manual):
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B230F, B230FT and B234F Throttle Body Adjustment
1) Open the lower end cap of the throttle linkage rod, pop off the end cap and remove the throttle body.
2) Back off the idle stop screw. Loosen the TPS switch. If you have any doubts about the TPS switch then test with an ohmmeter connected between the centre and outer pin (one outer pin is for idle closed the other pin is for WOT full open -not used).
3) Make sure the throttle plate is centered and can close properly without binding -look through the throttle body at a light source and ensure an even ring of space around the edge when closed.
4) Hold the plate closed. Advance the idle stop screw until it just touches the stop and the plate is about to start opening. Advance 1/4 turn more then secure with the lock nut.
5) Adjust the TPS switch. As you know, it should click immediately as you move the throttle away from its stop (and click again on the return). Start with the switch rotated clockwise away from the stop position. For a Bosch switch, hold the throttle plate closed, turn the switch counter-clockwise until it clicks then continue to end of travel and lock in place. For a VDO switch, insert a .010" feeler gauge at the idle stop screw (if you don't have a suitable feeler gauge substitute two strips of medium heavy bond 24 lb. computer paper), turn the switch slowly counter-clockwise until the click is heard then lock in place.
6) Re-mount the throttle body. Connect and adjust the linkage rod. For a B230FT (or B230F on a 740), insert a .10" feeler gauge at the throttle *spindle* stop tab (not the idle stop screw). Adjust the linkage rod so that the throttle begins to open and the TPS click is heard then adjust it back to the point where the closing click is just heard and secure the rod adjusting nuts. For a B230F on a 240 use a .08" feeler. For a B234F use a .13" feeler (.06" for the early '89 production B234F's w/auto trans).
7) Re-adjust the accelerater (gas pedal) cable as needed for a little slack making sure the cable is properly seated in the spindle.
8) For an automatic, you should then re-adjust the downshift cable (next to the throttle cable) -see the FAQ.
9) Re-install all vacuum lines. Replace any that are split or loose on their fittings. Make sure you haven't pulled the other end of the lines off their fittings, especially the ones on the charcoal cannister (big black plastic cannister up front). Don't forget to replace the TPS connector -easily forgotten.
10) For an LH 2.2 system, check/reset the base idle using the thumbscrew while grounding the idle control valve signal from the open test connector on the fender -see the FAQ.
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Dave -own 940's, prev 740/240/140/120 & quasi-expert only on a good day
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