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Has Service Bulletin #135 (Jan 1990) been applied?
It says it's for, "cold start difficulties...caused by a rich fuel mixture during engine crank and cold start warm-up functions."
Apparently the CS injector + side was originally wired from the radio Suppression Relay, and controlled on the ground side by a temp-sensitive ground in the ECU. So it must have squirted continuously until the temp sensor opened the ground side, which lead to an over-rich mixture right after starting.
The Service Bulletin brings the + voltage to the CS injector as in the older cars—from a starter terminal that provides voltage only when cranking.
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.
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 #135 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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