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Old 07-18-2005, 01:46 PM   #11
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My N/A was getting horrible milage until I replaced the cat. Doesn't sound like your problem, though...

I'd suggest a tune-up, too.
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Old 07-18-2005, 01:56 PM   #12
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well the PCV valve was replaced when i got the new upper, the new upper came with a new PCV valve surprisingly enough, and we replaced the plugs as well, wires are still on there though, but wouldnt it be running crappy if they were bad? i dont think anything having to do with the fuel pump, filter, or fuel pressure because its definetely getting fuel. here is my typcial day of driving to work:

5-6 miles of hilly gravel road, speed between 25-30mph, frequent revving between idle speed and 2500 at most

2 miles of curvy backroad, speed limit is 55...i usually accelerate onto to it mildly between 3k and 3500...then i put it in OD and run about 65 on it..

15 miles of open highway, speed limit 65, i mildly accelerate again up to about 70mph, set the cruise with AC, btw AC is on the whole time on the other ones..usually the revs stay right at 2k or a little over, i might pass 3 or 4 people at most and maybe go WOT one of those times.

rinse and repeat on the way home, done 5 times a week.

how much is a new o2 sensor? and how much is the special tool to change it? or is it even necessary...can a good mechanic tell me if its working properly or not? arent there two o2 sensors?
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Old 07-18-2005, 02:14 PM   #13
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There are two O2 sensors. One behind the cat, and one before it. The one you need to be concerned about is the one in front of it. It'* visible by looking straight down, from above the engine, on the back side. It'* by the firewall and is bolted into your exhaust manifold down pipe.

New from GM they're about $65. I would suggest starting there since you don't know how old it is. I replaced mine on the 99 at 105K and I got 3-4 more MPG out of it. It was the original. They get lazy overtime, but won't necessarily throw a code.

As for the special tool... Go to your local AutoZone and ask to rent the O2 sensor removal tool. It'* basically a socket with a slit in the side of the case to allow for the wire to hang out. It'* very handy and makes the job SO much easier!
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Old 07-19-2005, 03:35 AM   #14
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I get 14-17 stop and go

25-33 freeway

Stop and go is pretty bad
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Old 07-19-2005, 07:24 AM   #15
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Your commute is less than desirable for fuel mileage. Consider an O2 and hope for the best.
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Old 07-19-2005, 01:36 PM   #16
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Well I get 28.5 on the hwy, with my heavy foot! Extremely heavy 80mph in 65 zones! (only when truckers upset me happens sometimes) I try only to 7mph or so over! And in town with my heavy foot for accleration I see oh maybe 17-19 depending on how late I am! I know I need to slow down, my wife told me getting the Bonnie SLE was only going to encourage me and fast and spirited driving! Oh well I liked the thoughts of that! Cat converter? Air Filter, Fuel Filter or just a good old tune up might help your Bonneville SE!
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