Poor fuel economy -- 97 J30

[Pogophil]

My dad's 97 J30 has such poor fuel economy, he's ready to sell it. He is estimating 12 mpg. It has the common sluggishness issue -- we have already replaced the knock sensor.

I know this has been discussed a bit already, but nothing much definitive when I searched. Has anyone solved this issue? If so, what was the solution?

Thanks in advance.

[gr8scott72]

O2 sensors? MAF sensor?

What does he ACTUALLY get? Miles divided by gallons.

The J was only rated from the EPA to get 16 city so 13 isn't far from what it was designed to do.

[Pogophil]

thanks for the reply.

o2 sensors and maf sensor would trigger codes if they were faulty -- but there were no codes.

i didn't check the mileage myself, my dad did. let's assume he calculated it correctly.

fyi -- the 97 j30 was rated 18 mpg city/23 hwy. his 12 mpg is considerably lower than that.

[gr8scott72]

thanks for the reply.

o2 sensors and maf sensor would trigger codes if they were faulty -- but there were no codes.

i didn't check the mileage myself, my dad did. let's assume he calculated it correctly.

fyi -- the 97 j30 was rated 18 mpg city/23 hwy. his 12 mpg is considerably lower than that.

The o2 sensors or maf could be starting to go out without throwing codes and I got my MPG info from http://www.fueleconomy.gov/.

I think they have gone back and applied the new mpg standards to the old cars.

[puck]

Just thought I'd chime in too. I would not rely on the MAF or O2 sensors to throw codes for the type of problem you're having. My car did not start reliably and had poorer gas mileage (J30's gas mileage suck's even at its best) when I first bought it than after I cleaned the MAF sensor. The difference in starting was striking. I later realized it helped with gas mileage.

I would definitely clean you MAF. Its so easy and could improve your performance.

[Pogophil]

Just thought I'd chime in too. I would not rely on the MAF or O2 sensors to throw codes for the type of problem you're having. My car did not start reliably and had poorer gas mileage (J30's gas mileage suck's even at its best) when I first bought it than after I cleaned the MAF sensor. The difference in starting was striking. I later realized it helped with gas mileage.

I would definitely clean you MAF. Its so easy and could improve your performance.

i've already cleaned the maf -- didn't help.

thanks for your replies.

[driverdriver]

Have you replaced the fuel filter?