98 durango gas mileage problem

[transam1144]

So I own a 98 dodge durango 5.2L (113,XXX miles), I'm driving back up to school today and I notice I'm getting about 7MPG, when I should usually be getting around 12. I notice the truck is idling a lot louder(higher pitched) and it's a lot lopier (if that's even a word), almost as if it has a heavy cam in it. The idle is around 600rpm (rpm's haven't changed). I also notice as the truck is driving, around 65/70mph i let go of the gas and the truck halts and slows down almost as if the drive train was getting snagged somewhere. Midway through the drive the Check Engine light came on (I suppose a OBDII scan would be a good place to start). I wasted a full 24 gallon tank just getting to Albany from Long Island (190 miles). I don't think my brakes are getting hung up because there's no smell, and there's no gas leaking anywhere from visual inspection. I will jack up the truck tomorrow and spin the tires to see if they spin freely. Other than that could it possibly be clogged injectors? Fuel pump and filter were changed about a year and a half ago.

Any help/input would be appreciated.

[1BaddLS1]

run techron
consider new o2's
spark plugs & wires etc
clean electronics w. a cleaner
check tire pressure
take extra shit out of the truck (weight)
check for vaccum leaks

go to autozone to see if any codes stored


good idea about checking brake problems

[transam1144]

engine was too hot to check plugs/wires. does the auto-zone OBDII scan cost anything? everything except the O2's, plugs/wires i've checked or done, its a great list though thanks a lot for the tips. i'm leaning toward an ignition problem though (plugs/wires) since it seems like it's only running on 7cyls.

[Tudds]

If you stop by my lot I'll scan it for you
529 East Jericho Turnpike
Quick Cash For Cars

[diggla]

run techron
consider new o2's
spark plugs & wires etc
clean electronics w. a cleaner
check tire pressure
take extra shit out of the truck (weight)
check for vaccum leaks

go to autozone to see if any codes stored


good idea about checking brake problems

:iagree:

[1BaddLS1]

does the auto-zone OBDII scan cost anything?.

free

i also have a obdII scanner (South Baldwin)

[transam1144]

thanks alot guys i really appreciate the offers to scan it for me. unfortunately i am up in albany at school until mid may. i'm just going to go to autozone today after class. if i have any problems while at home with the trans-am or durango, i'll be sure to take u guys up on that offer, thanks

[transam1144]

the code that showed up was a P0171 which is a bank 1 (air/fuel ratio) too lean. the guy at pep-boys said it could possibly be the pre-cat O2 sensor

[BadBoy4Life RS]

ya run some techron through might be the injectors. and autozone is free scans.

[95TA04GTO]

A bad o2 sensor shouldn't throw a lean running code. I'd check for vacuum leaks on bank 1 (the side with cylinder number #1), check the EGR. If it's on that side of the intake and stuck open that could cause the problem.

[tkayrc3]

Actually in most cases you are right about O2's not causing lean codes but in this case I've seen it before on some chrysler v8's a simple way to check:


Using a compatible scan tool, check the O2 sensors' operation.

Within 20 seconds after start-up the O2 sensors should drop to less than 1.2 volts.

After closed loop is reached, both O2 sensors should be switching with the upstream O2 sensor switching faster than the downstream O2 sensor.

An O2 sensor staying lean while the other O2 sensor switches or goes rich, indicates a bad sensor.

john