84 B23F. I've been on here for this problem before. When I first start the car it runs so rich, it sounds like it's missing. Heavy black exhaust smoke and smells like gas. I know it's not missing because I replaced the plugs, wires and cleaned up the newer cap & rotor and no change. After a few minutes the car runs fine. It takes longer now since the weather got colder.
The wires going to the temp gauage have been replaced and it works fine. I can't tell the condition of wires going to the other temp sender from the bottom because there is no room to get to them. I peeled back the upper portion of the harness and it looks like new. I think the blue wire is the one in question as well as a ground. I have an extra 2 prong sensor from an 81 B21F in good shape. If I could get to the sensor plug, and get it undone and plug it into this one, could this be a way of testing it? Is this the wrong sender to use?
Am I barking up the wrong tree? Blown head gasket? Screwed up MAS meter? I'm lost. A few years ago I plugged in a MAS from an 86 B230 to see if it works (It didn't) Actually it ran exactly how it does now. Heavy rich with a miss.
Only one other possibility. I had a bad plug wire that was shorting the coil last summer. There was lightning zapping across the coil terminals. A new set of wires and pluges cured that, but could it have somehow delay damaged the MAS since it's only a few inches away from the coil?
Ben

Have you checked the other posts on the Fuel Pressure Regulator? I recently went through this. It was a combo. The vacumn line to the FPR was plugged at the intake nipple, and the ECU was bad. No codes and no check engine light.

I'd definately suspect the temp sensor. You need an VOM meter to test the resistance of it. You also need a manual for the car!
The best place to test the temp sensor is right at the computer terminals, then you know if it and the wiring are OK.
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745-4+OD-16v, 744-4+OD-16v, 245SE auto, 242 4+OD Turbo

I'll need a beter manual than my Chiltons. There are no wiring diagrams in there. I'll check the main library they actually have the real repair manuals there and photocopy what I need. I can borrow my brother's Voltmeter.
As for fuel pressure, I think it's good, otherwise it would run like crap all of the time. I replaced part of the fuel line this summer. There was plenty of pressure when it sprung a leak. I think the temp sensor has to be it.
Thanks,
Ben