I think Bosch is not liked by our cars. Might be the issue here. The rest of the tune up suggestions are good maintenance Items at this time as well, so check those also. Willwren can give you more info on the O2 sensor.

yeah check out gmpartsdirect.com for the O2 or see if autozone has the delcos....they used to but not sure anymore.


I had a problem with my bosch among MANY others.

with my terrible driving habbits I can still manage 19 in stop and go traffic never getting above 40mph or so.


Something is wrong, maybe O2 sensor I thought I did not have an O2 sensor until I fixed with a delco that gave about 3mpg though, Unless someone is stealing your fuel you may have a more serious problem with running too rich it seems.

99_Bonne_SLE, let'* get back to basics for a minute:

Have you ever checked or changed your plugs and wires?

Is your car showing any signs of malfunction like sluggishness, hesitation, or missing?

Have you done a careful visual check underhood? This should include a good look at your vacuum lines and their rubber connectors.

Otherwise we're just chasing our tails here.

Hans, before we jump on the 02 bandwagon, let'* consider that he just changed that 3 weeks ago, so that wouldn't be his primary culprit right now. He also hasn't described any issues that would lead us to believe he is experiencing any symptoms besides bad gas mileage... yet.

lash;
Back to basics. Haven't done the underhood check yet other than checking the PCV. I do check fluid levels on a regular basis and have the oil changed every 3,000 miles, this also includes having tires rotated. When I check the oil, I generally look for any signs of contaminates etc., same goes for coolant.
What seems strange is the gradual loss of MPG.
As for hesitation, sluggishness or miss firing. No miss firing or sluggishness but do experience hesitation sometimes when I stop or slow way down then accelerate. If I really step on it(similar to a post here by someone else) it will finally take off. This does not happen on a regular basis and even told the guy that did the tranny overhaul (lost fourth gear)a couple months ago. I thought maybe there was something wrong but still does it after overhaul.
I tried to get the PCV out yesterday but it was stuck and didn't have time to mess with it yesterday but will do it today.

When was the last time the plugs and wires were changed?

Also, on that PCV valve. You might as well pick up a new one on the way home tonite. While it MAY still be good, they are cheap (as pointed out above) and it sounds like yours has been in there a good long time.

lash;
Thanks for all your input.
Will buy a new PVC today and install it.

As for plug/wire replacement. I bought the car with 50,000 miles on it and have never changed them. I was planning on doing this but unsure if I should buy the wires from dealer. GMdirect doesn't seem to carry them.

Anybody out there have any suggestions?

Napa belden premium wires with autolite APP606 plugs should be just right for you. Good prices too.

I have AC Delco wires with the iridium plugs in my car right now and I'm super happy with the performance I'm getting.

I don't know why, but our cars seem to eat Bosch products and spit them out. Check this website out, cheapest supplier I've found yet for AC Delco products: http://www.rockauto.com. My brand new O2 sensor was like 45 bucks shipped.

have you tried copper autolites? My SSEi runs better on them than iridiums.

Update:
Went by NAPA and purchased a new PCV but the box did not have a new O-ring in it.
When I questioned the guy about that, he said there is no O-ring on a PCV, just a grommet that goes in the valve cover. I told him this was in an electronic module and required an O-ring. He said he never heard of such a thing. I took him out and showed him where my PCV was located and he said he never saw one located there. I went ahead and purchased the PCV and used the old O-ring, which seemed to be in good shape as was the old PCV but replaced anyways.
As for the O2 sensor, I called Advance Auto about the Bosch sensor I purchased there back in January and when I explained the problems these have caused with most Bonney'* he said bring it back for refund since it was within the 90 warranty. I priced a new ACDelco there and it was $129. I looked at rockauto.com and purchased one there for $76 including shipping. It will be here in 5 days, but will go back to Advance Auto to get their wrench to install it. They require a $15 deposit for it'* use which is refunded when it is returned. Not a bad deal. I will probably purchase plug wires and plugs there since their price for same item is within a couple of dollars of rockauto.