Fuel Efficiecny Drop

[Wup]

I purchased 2000 pontiac grand prix SE in 2008 with 114000km on it (now it has 125000km). I used to get around 450 km/tank when I first got the car, however I am not getting about 300 km/tank. All of this is city driving. The car has had some previous lifter noise, but it has started to have a ticking noise. I pulled 2 spark plugs, one of them had an abnormally large gap, and one of them smelt like gasoline, and was visibly wet. We disconnected the wire to the one that smelt like gas and the noise seemed to subside a bit. Any ideas what could be wrong:
- Bad plugs?
- Coil Pack?
- Wires?

Also could the EGR or PCV valve be affecting the fuel efficiency? I have already changed the air filter.

Also, could someone describe how to access the back three spark plugs?

Thanks for the help,
Wup

 

[Pittman06]

do a full tune up including plugs/wires, fuel filter, pcv and get back to us. On the back 3 on a 3.1 i'm not sure, most gm's if you cant jam your hand back there take the dogbones off and rock the engine forward. Not sure if the 3.1 is that way or not though

 

[Wup]

I put in new spark plugs, wires, oil change, oil filter, and PCV valve, and the fuel efficiency is the same.

I'm getting at my wits end. o2 sensor seems to be cycling properly.

Any other ideas?

 

[Zef_66]

It is winter. Your fuel efficiency will drop.

 

[Wup]

I was getting this same fuel efficiency in September/October. But even in the winter time, 50-60% of what the MPG's are supposed to be is normal?

 

[TorqueAutoMotiv]

hows the cars performance over all still running the same?

 

[Wup]

Performance seems to be the same, smooth acceleration, no power loss, etc.... Operating temp is 180 is this correct as part stores list OE thermostat temp at 195?

 

[Zef_66]

Performance seems to be the same, smooth acceleration, no power loss, etc.... Operating temp is 180 is this correct as part stores list OE thermostat temp at 195?

Stock t-stat is 195°F and where you will get the best MPGs.