PontiacBonnevilleClub.com

Hey guys,

For a long time I was getting like 16 mpg and everytime I started it she bogged and spit and sputtered and blew smoke for a few seconds until I gaver her some throttle and cleared the cylinders. The codes read crank sensor input so we replaced the crank sensor. That did nothing and we kept getting that *dang* crank sensor input code. So I bought a used PCM from the same year and trim car and slapped that in and now it starts fine and I'm getting like 5 miles per gallon better but still not the 25-30 which I figure I should be getting. I have not gotten a code yet since I installed the new PCM and everything is cherry except for the gas mileage. The last time I calculated it I got 21.5 mpg but I wasn't babying it while driving during that tank so this next time I calculate mileage I'm gonna baby it to see if its just my driving.

What do you think?

Thanks,
Bumpin'

Is that mixed, city, or highway?

Well if you're drivin around with the 3.06:1, you're not SUPER gentle on it, and that is combined mileage, you're probably fine. I averaged between 21-24 in all three of my Bonnevilles, LN3, L27 and L36.

that's about what I get in my 98 SE (3.05 gears) mixed city and freeway miles, though mostly city miles with A LOT of stop signs and lights.

What final drive ratio do you have? (Check RPO codes in TechInfo to find out.) My car has the 3.06 and I don't get any better gas mileage than you do. With mostly highway going to work and back each week, I consistently get right around 21 to 22 MPG. On the drive up to WCBF, 10 hours of 100% highway driving, I managed 26 MPG and later 24 MPG. But I've never gotten more than around 22 on regular drive to work weeks. 19 MPG is common for me when they have winter blend gasoline, or if I'm not driving mostly highway.

Wes wrote:Is that mixed, city, or highway?

Almost all city miles but a few 6 mile trips on the freeway here and there. I was just curious as to what I should be getting because I have seen numerous bonnevilles for sale claiming 30mpg and close to that. Also My brothers 1997 Grand Prix SE (3.8) gets around 27mpg although I'm not 100% positive on that number.

FWIW the fuel economy is "supposed" to be 19/city 30/highway

I average anywhere from 17-25 in the city. You just have to learn self control and stay out of the throttle, which is hard to do by the way.

yeah, if thats all city, then you're fine.