My KA is getting VERY crappy fuel mileage and performs like crap as well. I changed the plugs, wires, cap and rotor when I bought the car (standard issue half-*** tuneup). The air filter is fine as well. I need to adjust timing for sure, but I don't think that's my only problem, as I get losses of power at random, and a few seconds later it will come back. Strange. The exhaust smells like a lawnmower (not weed whacker, indicating burning oil), and doesn't give off any black smoke at takeoff. She idles low, at 550 in drive without the A/C on, and abut 600-700 in drive with the A/C on. When I have it out of overdrive and coast from about 45, it smells like I'm dumping fuel hard. Smelly exhaust. I know that normally, exhaust shouldn't smell too bad, but this is like a 1985 chevy C-10 with a carbureted 350's exhaust.

Any ideas where to start, aside from timing?

 

check o2 sensor, if its bad it will use lots of gas.

 

Any idea how to test an o2 sensor?

 

Turn key to "on" position then turn ECU screw fully counter clockwise, wait 2 seconds then turn fully clockwise. This will set the ECU diagnostics to mode II for o2 checking. Turn key and start the car and let it get to normal temp. then run RPM's at 2000 for 2 min while looking at ECU light checking to see if it flashes on and off more than 5 times during 10 seconds at 2000 RPM's. If it does flash on and off more than 5 times during 10 seconds the o2 is good if it doesn't the o2 is bad.
Hope this helps.

 

Ah. Well today I'm gonna pick up some stuff to clean my TB and MAFS, maybe a K&N drop-in filter... I think after all that, I should be close to solving the problem. If its not the mafs or o2 sensor... then its gonna be a long hard day.

 

Good luck!!