I shall enlighten you on all (well, most) things B23F...

'83 and '84 were the two models years that NA 4-cyl 240s came equipped with the B23F. It's a good, solid motor - most got a forged steel crank, thick rods, etc... Be glad you got one!

All B23F motors are equipped with Bosch LH-Jet 2.1, regardless of what Haynes or Chilton's may say. This is a robust fuel management system, fully electronic, doesn't usually give many problems. The CIS (Continuous Injection System?) usually refers to the Bosch K-Jet injection system used on nearly all B21F and B21FTs. Because the B21FT was produced concurrently with the B23F, confusion often results in the manuals. There is an idle control circuit in LH 2.1, consisting of an air bleed running through a small stepper motor/valve.

All B23Fs have a Chrysler-manufactured ignition control unit. There are two model numbers, depending on what compression ratio you have in your B23F. All automatic-equipped B23Fs had a 10.3:1 static CR, while only a few manual-transmission cars in early '83 were given the 10.3:1 motor. The balance received a 9.5:1 CR motor. Whether or not using the wrong control unit would cause a problem, I don't know for certain - but I doubt it. The Chrysler computer controls the ignition timing based on RPM, vacuum and a knock sensor input. Basically, when you crack the throttle open, the ignition advance will try to swing to ~52* advance, or until knock is detected. If knock is detected, it will back off and continually alter the timing as advanced as possible without knock. The knock sensor is located where you mentioned seeing it, below the temp sender on the intake side.

Some B23Fs, mostly '83s, got a Chrysler (white cap) distributor. While it's not a glaringly cheap product, it is inferior to the Bosch unit. Chrysler used cheap tin contacts and some really chintzy foil grounding strip, which can cause problems when you least expect it. Once, I had to fix mine with a piece of foil gum wrapper I found on the side of the road. Late '83 onward, a Bosch distributor was used. This model of Bosch distributor is a drop-in replacement for the Chrysler. It uses the same round plug as the Mopar (not square, like the later Bosch units.) Be glad you don't have the Chrysler distributor. I swapped mine out for Bosch.

About the blue connector - I'm not entirely sure about that one. There is a blue connector behind the battery, near the relay array on the driver's side, which has two connections for diagnostics (one is to set idle speed, the other reads O2 sensor voltage.) I'm tempted to say that the blue plug indicates diagnostics, but I don't know for sure. The other explanation about the wagon washer tank seems plausible.

So I've probably told you far more than you wanted to know, but I hope this helps. It's taken me 10 years to amass my B23F knowledge, so I try to share as much as I can.



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Speed Racer, '83 240 R, '74 164 E, '93 940 OL1 (Manchester, CT)