[antoniomontana0]

I have a 2003 Zetec focus. Last thursday, I started the car as usual, and it didn't start at first. A few tries later, the engine started, but at VERY low RPM's. I cheched the coil/wires and any obstruction on the CAI, and I didn't found anything. I started the car again, and this time I revved it slightly. A few moments later, the car worked normally, but since then, my fuel economy is really crappy.
There is no check engine light, so I don't think is any sensor failing. I haven't made an oil change since January, but I think that's not a problem, since I always use synthetic oil, which is supposed to last longer. I also use Restore oil additives.
The spark plugs are old, but they'e Iridium spark plugs, also supposed to last longer. I checked them and they look fine.
If you need any pics, let me know and I'll post them as soon as possible.

Thanks!

 

[Mike_Mac]

fuel filter? they should be done every like 20k

 

[whynotthinkwhynot]

It sounds like you should do a few other things with your tune-up.

Clean the MAF with spray MAF cleaner. Make sure you shoot it into the hole in the side of the MAF that faces incoming air.

Fuel filter if not done, but I doubt that's it.

PCV valve check: remove the PCV valve line from the TB and blow into it. Just like with the Galaxie, you should feel resistance to your blowing. If not, you either have a hole in the line or the PCV valve is stuck. If it passes the blow test, then hook it back up and turn the engine on. Now feel the PCV vacuum line to see if it's collapsed at the rubber elbows.

The next time you feel like checking your plugs, re-gap them. Gap does change slightly over time, so it's worth checking.

 

[antoniomontana0]

Thank you very much guys, I'll check everything tomorrow and I'll let you know what happened

 

[iminhell]

My first thought, Throttle Position Sensor.

 

[antoniomontana0]

My first thought, Throttle Position Sensor.

Well, it could be, but the check engine light is off...

 

[iminhell]

Doesn't mean there isn't a stored code.