1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Crappy Gas mileage

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Old Nov 10, 2007 | 09:50 AM
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Default Crappy Gas mileage

Alright, so my 92 SE seems to be getting crappy gas mileage compared to my LeSabre. Last time I calculated it, it came out to be about 18MPG for about 70% Hwy and 30% city driving. The car has F17 gears, newer tires and it is all stock as far as I know. 136K. I'm not sure if this is normal or not, but as I said, it seems to use fuel faster than the LeSabre did, and that LeSabre had 146,000 more miles! Regardless of normality, is there anything I can do to try to improve mileage? $3.15 for regular is starting to hurt! Thanks a lot guys.
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Old Nov 10, 2007 | 12:12 PM
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No SES, wouldn't an o2 cause a light and codes?
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Old Nov 10, 2007 | 12:39 PM
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Check for ANY vaccuum leaks you may have. Leaks will cause the O2 sensor to read leaner than normal, thus signaling the computer to add more fuel than normal.

I found a HUGE leak in my EGR gasket, and nobody ever thinks about looking there.
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Old Nov 10, 2007 | 12:49 PM
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I believe '92'* don't have EGR, so probably not there. But I'll check out the o2, because it has had a tune up recently.
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Old Nov 10, 2007 | 12:51 PM
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Well we could get a scan on it depending on how far from Milwaukee you are? Good to see another Wisconsinite on here.
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Old Nov 10, 2007 | 02:04 PM
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Default mpg

My SSE was getting poor mileage and I checked or replaced all the normal items with no results.
I then pulled the platinum plugs and installed good ol Champion coppers going one hotter on the heat range. You wouldn't believe the power and mileage increase!
Driving my two cars the SSE has better low end torque and highway pickup also.
You would think it had the 205HP and the SE had 165.
In your case it still could be a lazy 02. You can pull it out and tell us what color grey it looks like. Light chalky, medium or dark.
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Old Nov 10, 2007 | 05:27 PM
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I live about 2 hrs from MKE, but it might be fun to have an America'* Dairyland meet sometime! I've ordered an o2 sensor, and it should be here on monday. Where is it on the car?
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Old Nov 11, 2007 | 01:23 AM
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Check your tire pressure too... Even only a few lbs being low will definitely affect your mileage. I've learned that first hand. The correct air level will be posted in the manual and also on the driver'* side front door sticker.

It makes a difference, too, if the tires are cold or hot (after being driven). They will have more pressure when hot.
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