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1989 245, 230K. B230F with LH2.4.
Getting about 15 MPG, mostly city driving and short trips. On cold start, it idles rough, smells somewhat rich, has a misfire. Rev it up and it will usually smooth out okay and idle better (but not perfect). Seems to run decently around town and on the highway, but does not have as much power as normal. There was a definite sudden onset of all this when cooler weather (and crappy winter gas) arrived. One day it was fine, next day I was dealing with all this. Gave it an Italian tuneup one day, and the next morning it behaved itself. 2nd morning, back to these problems.
Think I have investigated the usual suspects. Tested O2 sensor output with multimeter, it responded to lean/rich conditions as it should. Confirmed that TPS is operating correctly (one side only has continuity at closed throttle, the other side only has continuity at WOT). Tested ECT output with engine hot and running, got the .5 volts as in the FAQ. Tested it cold and running, got the 3 volts as in the FAQ. ECT is 18 months old, replaced preventively when the head was off. FPR is fairly new Bosch, no sign that diaphragm has failed. (I have an extra new one in the box, think I may swap it on tomorrow just to see if it makes a difference.) AMM is a recent rebuilt unit (Injection Labs, from FCP). I did clean the AMM connectors this morning (someone slathered dielectric grease all over it, possibly enough to compromise the contacts) and things seemed better when I restarted the car. Running it with AMM unplugged dramatically worsened the idle. Never a single OBD code.
Took it to the mechanic down the street, who generally knows what he is doing and is trustworthy. He checked fuel pressure, ECT, O2, TPS, vacuum leaks, confirmed injectors were not leaky and had good spray pattern, confirmed good spark, checked operation of cold start injector. threw up his hands and suggested I move up to slightly hotter plugs because "gas ain't what it used to be". I run 93 octane from Shell (10% ethanol, because that's all we have around here), which can't be but so bad.
What else should I check? Was planning to drive the 240 to Atlanta next week, but I will have to reassemble the 940's dashboard and drive it instead if this continues.
John
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