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Hey Phil,
I've had a couple of these cars (83 and 84) with the LH2.0 B23F engine. Cut my Volvo teeth on them, so to speak. Despite the commonly held notion the platinum wire breaks and makes it run pig rich, I've never seen this happen -- all of my AMM troubles were on the lean side.
However, I was introduced to the "stuck regulator" mode on one of these cars. Stuck, not its diaphragm holed. A necropsy of the fuel pressure regulator found the small spring at the valve's ball (equivalent to the valve stem) had rusted into two pieces.
Another pig rich episode was brought on by a crumbly engine coolant temperature sensor (ECT), which I've pictured below. It was connected to a crumbly wiring harness. Both can be checked in one fell swoop by measuring the voltage at pin 2 on the ECU.
Interpretation of the reading is discussed in the 7/9 FAQ, but basically, the voltage approaches 5V to tell the system it is located at Pt. Barrow Alaska in January, and since these cars do not have a cold-start valve (injector) it pours the coals to the motor it thinks is at -40F. Most folks just pull the ECU plug and measure the resistance back toward the ECT, to compare with the chart in their Bentley or Haynes.

--
Art Benstein near Baltimore
Do plumbers who become electricians install outlets upside-down? Hot on the left?
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