I am trying to diagnose a rough idle and possibly rich fuel mixture on my 1991 240 B230F with LH2.4 EFI. It overheated 10 days ago ("Brick Oven") and ruptured the cylinder head gasket. Thanks to advice from the Brickboard, I repaired everything myself! The car is running again, except for a couple of annoying problems...

When I start the engine, the car has trouble idling for the first 5-10 seconds, and I can smell excess gas fumes in the engine compartment. After 20-30 seconds, the idle holds but is still very rough. The timing belt was set correctly. My timing light reads a steady 12-degrees BTDC at idle. I am currently running 92-octane fuel. The intake manifold gasket, exhaust manifold gasket, vacuum hoses and AMM air hose have all been rechecked for vacuum leaks. All are new or in good condition. Almost everything everything else is controlled by various sensors. I think I have narrow it down to a few possibities:

- KNOCK SENSOR: Initially, the knock sensor did NOT have a washer on it. When I had the cylinder head resurfaced, I pulled the sensor and lightly scrubbed it with sandpaper. (WHY, stupid? Because I wanted everything shiny inside and out...) The cylinder head kit had several copper and cork washers, so I placed a new COPPER WASHER on it and installed it snugly into the cylinder head. Can a few people someone check and see if their B230F knock sensor has a washer installed? Would this cause a faulty reading? Shouldn't this this affect timing, also? Does the knock sensor contact the coolant? Do I have do drain the engine block before pulling this sensor?

- ENGINE COOLANT TEMP SENSOR: just below the knock sensor is the engine coolant temp sensor and plug. When I pulled the cylinder head, I also removed it, "cleaned" with sandpaper, and replaced the copper washer, and reinstalled. If a B230F engine overheats (BONE DRY), will this damage the engine coolant temp sensor? I will also check the electrical connector for this sensor...

Are these sensors "dealer-only" items? Besides IPD, is there another source for OEM replacement sensors. Is there another sensor that I should check, or something else I am forgetting, after having performed the cylinder head job?

[[ southern fried volvo - 91 240 B230F 132k mi lh2.4 efi ]]