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Fuel mileage still sucks! There is no freaking way that this car is running so much better, and the fuel mileage is exactly the same!

Last tank: 20.2

I give up!

Come winter time, little ricer boy better watch his @$$, because by golly if this car is going to tear through gas that fast, I am going to give it a reason to tear through gas that fast!

Did you reset the computer by taking the battery wires off for 30+ minute to reset fuel trims? And give it a tank or two to come back... You're probably flooring it too much.

New found power probably isn't helping you... Also, is that MPG all city or mixed driving?

BonneMe wrote:Did you reset the computer by taking the battery wires off for 30+ minute to reset fuel trims? And give it a tank or two to come back... You're probably flooring it too much.

I didn't, I was figuring the computer would figure it out, but I can see the wisdom in your suggestion. Thank you.

I have also been running the A/C a lot as well, which sucks power BAD. Pretty sure there is something up with it, but won't even consider addressing it until it blows up.

I also have been catching a whiff of gas fumes after it has been running a while, I think there is something up with the fuel tank seal, but not quite sure.

As far as new found power? It doesn't see WOT nearly as often as it did before, I feel like it is going to hurt itself it gets prodded too often, it is running that good

It gets saved for when someone needs to be dispatched with extreme prejudice

I will prolly go disconnect the battery here in a bit.

just for your comparison, i drive a 95 PA NA Jacksonville FL. mostly suburban meaning 35-45 mph speed limits. seldom ever shifts into OD. i think it has the 2.86 gear ratio. gas mileage always between 18-20 mpg.

gmman wrote:just for your comparison, i drive a 95 PA NA Jacksonville FL. mostly suburban meaning 35-45 mph speed limits. seldom ever shifts into OD. i think it has the 2.86 gear ratio. gas mileage always between 18-20 mpg.

The '91 Olds, when it sees 30-50mph all city stop & go, gets 17-20 mpg as well, though if you go 100% highway with few if any stops, it'll do 29 mpg, even at 70mph. My '98 Z34 L36 got nearly identical mileage as well in identical conditions. Don't know what your makeup of driving conditions are at, but what will it get on a 100% highway trip, with average acceleration?

If it was all city (25-45mph) with a lot of stop and go I would expect 18-20.
Country driving (55-60) with a few stops I would expect 24-26.
Freeway driving (60-80) with no stopping I would expect 29-31.

Most of my family's 3.8's will do 29-32 mpg on the freeway; except the SE right now only gets 26 max / 23 avg. That's with 200 miles of freeway and 150 miles of mixed city/fwy driving. Same conditions my LeSabre was getting 31 max / 26 avg, and it saw more throttle action .

Perhaps investing in a 250cc motorcycle (65+ mpg) is better suited to your daily commute?

It is not the amount of fuel it is using that is the problem. It is more of a what it uses vs what it should use.

For whatever reason, I was expecting mid 20's, or more.

If it is where it should be, I will just take it and move on.

I just remember people mentioning 30's on the road, with BonneMe menioning a 40mpg run accross MI.

Perhaps expecting too much?

40 seems like a stretch to me.

I have been noticing a couple points lower too. A few weeks ago I made a 4 hour drive to Traverse city driving my olds. I babied it the entire way and only managed 25 mpg. A few weeks before that, I made the same trip, but I was MUCH heavier on the pedal. I know speed discussions are discouraged on this forum, so I wont say how fast I was going, but I may or may not have buried the needle a couple times. I managed 23.8 mpg on that trip. With the same car, my best babied freeway mpg was just over 29 mpg.

I know you are no where near me, but I wonder if it is the mix of the gas. Is the max ethanol still 10% at the pumps, or have they been bumping that up?

And the people mentioning 30s are usually L67s from what I recall. Those only come from pedal restraint trips though. Any L67 is capable of consuming much more fuel if you step on it.

I was able to find ethanol free, and have been running that lately. I reset everything yesterday, and the computer is on track with the relearn so far. I plan on just driving it and getting what I get at this point.

It is 20 years old after all.

Ethanol is still 10% max, and will always be that way. There will be different pumps with 15% for 07+ vehicles, but I doubt anyone will use it anyways...

RJolly87 wrote: I just remember people mentioning 30's on the road, with BonneMe menioning a 40mpg run accross MI.

Perhaps expecting too much?

Yeah, I wouldn't get my hopes up for anything better than 27-30 mpg on a highway trip. I've known a couple people that could squeeze 32 or so out of one, but in all cases they were Series II cars with the tall gear ratios. Anything 32 mpg or better is usually done babying the car on a 100% all highway drive with no stops. The 3800's are good but not that good under normal circumstances. Any mid 30's to 40 is a rare occurance that may only happen a couple times in the ownership of the car.

Given the fact that yours is older, like you say, we can give it a little slack, but in good running condition, I don't see any reason it couldn't get at least 26-27 mpg on an all highway trip. When I first picked up my '91 Olds 88, it would only get 25-26 on highway trips, but after a tuneup it got a consistent 29. My Monte Carlo on the other hand, would get 27 no matter how you drove it...55 mph, 65, 75, 80....always 27 mpg, though I got 29 once.

The 40 mpg run was 2 club cars driving 120 miles and an early fill up before the Canadian border. Conditions, speed, terrain, etc really were factors.

Typically 30 on the freeway was possible under 75mph.

In town, 20-233 was where I always was depending on time of year, and driving habits as it was a college car.

Before the rush to get ethanol in all the gas around here, I managed to squeeze an average of 35mpg on my Buick during several different (over a 5-7 month period of time) 300 mile trips (back and forth from school, 60% highway, 30% country, and 10% city, and temps varying between 40* F - 90* F). I was feeling pretty awesome about it. And that was only with a CAI and high flow cat.

Then again, that was 7 years ago, when the car was much younger and running much better. I could probably never be able to achieve that anymore.

Have you thrown any fuel system cleaner like Techron or Regane into the tank? That was always good for a little bump.

The folks reporting mid-30's MPG were mostly Series II folks. I routinely got mid-30's with my Series II LeSabre, and a best of 39 mpg once.

Ran a can of sea foam a tank before the tune up. If Techron would be good to run also, may consider picking some up.

Seafoam was plenty. No need to run much through the tank.

Seafoam vs. Techron or something similar is no contest. The active ingredient in Techron (polyether amines) is the only cleaner that cleans carbon without leaving a residue itself. Chevron put a LOT of money into it, and it works well.

I'd try a bottle or two. A bottle of Gumout Regane High Mileage is still cheaper than Seafoam...

Techron is the good stuff.

Make sure you're not comparing mileage to L36 cars with longer gears...

Once you're in the neighborhood of typicall/target MPG, it's probably down to technique and controlling your impulses