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This may not help with your starting problem, but will help decide if the 3-2-1 code is significant or not.
Volvo Service Bulletin #135 (Jan 1990) addresses '89-'90 740s "cold start difficulties...caused by a rich fuel mixture during engine crank and cold start warm-up functions."
Apparently the CS injector/valve +12V side was wired from the Radio Suppression Relay (like the regular injectors), and controlled by a temp-sensitive ground from the ECU. That means it must have squirted continuously until the ECU opened the ground side, resulting in an over-rich mixture right after starting.
The Service Bulletin brings the +12V voltage to the CS injector as it was done in the older cars—from a starter terminal that provides voltage only when cranking. The temp-sensitive ground in/from the ECU is unchanged.
Pull back the boot on the CS injector and check to see if the original Blue/Green + wire has been removed, folded back, and replaced by wire (unspecified color) leading to starter solenoid terminal 15a or 16.
NOTE: A side-effect of this change is that OBD code 3-2-1 is permanently stored in the self-diagnostic memory (but will no longer set the Check Engine Light). That would also be a quick way to see if the SB change has been applied.
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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