My struggles with my baby continue...

The car:

1994 Buick Century, 3.1L V6, Distributorless ignition, common-rail injection, 1-coil/2-cylinders waste-spark system. 50,750 miles.

The symptoms:

Rough idle. The car diles fine for the first few minutes of running, but then settles out into a weaker idle and occasionally shudders. I had it die at idle once last year when I put from P into D.

Smell of unburnt gas. After a highway drive, I usually smell unburnt gas. I've also smelled it once or twice when I've come off of a long 40-45 MPH hour run, but that's quite atypical. The smell seems to come into the interior with the climate control -- when I turn off the blower, the smell goes away; when I turn it back on, the smell comes back.

Bad gas mileage. Like 20 MPG bad. I drive mostly highway or 40 MPH back roads -- to show that it's not a lead foot somehow killing the mileage or something, I've been averaging 38-39 MPG (beating EPA highway by 2-3 MPG ) in our Corolla all summer under similar driving conditions.

What I've done so far:

A cylinder balance test (shorting out one plug at a time to see if one cylinder is misfiring). All cylinders experienced a similar RPM drop.

Test all coils and wires for proper resistance.

Inspect spark plugs (replaced ~750 miles ago). All in good shape. There was oil on the threads of two of the plugs, but it looked to me like it had been leaking in rather than out, because there the most oil on the area right above the threads.

Clean MAF sensor, confirm that the car loses it's mind when you unplug it so it must be doing something

Disassemble & clean & test EGR and EGR passage. All clear.

What I'm looking at doing next:

Check that the EGR and MAF are receiving appropriate inputs & making appropriate outputs, as necessary.

Check compression, just because the oil on the two plugs is bugging me.

Go through fuel system. Reseal injectors and make sure that the injectors aren't leaking & have good spray patterns. Check everything else (fuel pressure, fuel pressure regulator, etc.) according to FSM (which I got for $30 on eBay, thank you SO MUCH for telling me to do so, TwitchKitty!)

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."