will_w204

I need a list of every possible culprit here. Best I can tell, I need to look at:

o2 sensor
MAF
EHA adjustment (correct?)

What else? help me compile a to-do list. I bought a new o2 sensor, still trying to get the old one off. Would like to look at the cheap/free adjustments/fixes first.

Elk

Fuel Filter
plugs/wires/cap if it's been awhile

ps2cho

Pull the engine codes first, then check for any vacuum leaks.

GEDaggett

Gotta run the codes. that will tell you if you have the 02 error as well as a host of other things. I wouldn't move forward to aggressively until you do that or you are just flying blind and dumping parts into the car. O2 can have a big effect on fuel but so can about 3 or 4 other major components all of which should have a code related to them if they are indeed malfunctioning. As far as the stuck O2 sensor get a propane torch and heat the sensor up till it glows red then douse it with water. repeat that a couple of times and then it should break loose with a good size 1/2 drive breaker bar (watch you fingers when it finally breaks loose) Hope that helps

Jim's500E

13 mpg? Sounds like your right foot loves the M119 motor.

PaulX608

My right foot loves mine, but I've never gotten less than 17. I think he's got him a problem. I usually average 21-23 in mixed driving, and I drive pretty fast on my commute. 80-85mph average, with occasional jaunts to triple digits two or three times a week. I've gotten as much as 26, but that was all highway at 70mph with no A/C.

will_w204

Yeah, it's definitely got an issue. There are codes from the last major service (btw, fuel filter and plugs are new, cap/rotors recent, 2 new ignition coils, and the wires look good). The codes were for MAF and coolant temp sensor. Duh, I know the MAF is the obvious culprit, but I think it's more than just that. I've had hard MAF failures on VWs and my 202 C230, and the mileage was never anywhere near this poor. We're talking a 30-50% hit. Anytime I go WOT on the highway, gray smoke pours from the tailpipe, visible in the rearview mirror. Definitely some massive fuel-dumping/richness occurring. Once the o2 is done, if no improvement, I guess I'll have to buy a rebuilt MAF (I haven't seen them new, and the rebuilts are $200ish). What does a malfunc coolant temp sensor affect?

GEDaggett

If the smoke is blueish gray it is most likely fuel and youare running rich. Replace the MAF and see how big an effect that has.