MPG just dissapeared... WTF!?

[CamoRunner]

Way uncool. I'm running a 2nd gen automatic I picked up from a shady dealership who wasn't even sure ont he exact year and as soon as I got it home the check engine light came on. It's been on since I've been driving it for about 4 or 5 months now. It's seemed to be just fine until I noticed a) the 4unner won't shift into higher gears past 40mph after a coldstart until I've driven about 5 miles, and b) coldstarts in the morning seem to diminish a suspiscious amount of gas.
HERE's my problem. Just yesterday I was driving from my house until I realized I was watching my fuel guage go lower and lower and lower and wasn't stopping. I drop about 14 miles and lost more than a quarter of a tank! I've never had the car looked at and I'm no pro as self-diagnostics but I've been looking around the forum for hours trying to find any helpful topics but nothing that seems to match my problem. If anyone has any ideas or can provide any clues as to how to solve this problem, that'd be grrrreat! Thanks.

 

[fourwd1]

First thing we need to know is, what engine ??

 

[CamoRunner]

3.0 v6. I unaware of the history of it.

 

[Red3.slow]

Well I say you start with that check engine lightthis is a good sight for pulling the codes your self.

Next you might want to look at spark plugs, replace the plug wires, and maybe the distributor cap. That takes care of the ignition system

As for the transmission it wont shift in to top gear until it has reached operating temperatures, you might want to have your trans fluid changed as well.

Also another thing you might want to do, is change your oil and put some rislone or sea-foam in to help clean the engine out. If this stuff doesn't help then it might be more serious then just the normal crap build up.

 

[regularguy412]

With some of the later model 2nd gen auto trannies, it's normal for them not to shift into O/D or for the converter to lock up until the trans fluid temp has reached about 170 degrees. In the winter , obviously , it will take longer than in summer.

On the fuel consumption,, sounds like a fuel leak to me. Look it over with the engine running . I had a fuel leak, tho not to quite that extent. The pulsator on the fuel rail that feeds the injectors was leaking. There was a heavy smell of fuel in the cabin. However, it was difficult to detect just the precise location of the leak.

MIke in AR