Ok I need help over the past few weeks the car has been running like crap for about the first 5-10 miles each morning spitting and sputtering a few pops and clunks if you give it gas. after a while it seems to run better.
now this morning I got gas and it went from 24mpg down to 19.9 mpg. this usualy is an o2 sensor problem but I alway have got a check in engine light in all my other GM cars.

Do you guys think it is the o2 sensor?
I was thinking about doing plugs, wires, o2 sensor and possibly a fuel filter?

where is the fuel filter located? under the drivers side of car?

I plugged in a paper clip on the plug under the dash the 2 top far right plugs and I got a code 58 and code 66

did I do this right? where can I find the codes for this car?

any help would be appreciated!
thanks
Chad

1992 Bonniville SE 3800

First off let me say that you did do the code check right I believe, and code 58 is a non issue (glitch) I don't know what 66 menas but I am sure someone will be along soon on that. I would say plugs wires fuel filter and o2 would be a good idea no matter what if its been a while, I know it made a world of diff. in mine! As far as the fuel filter goes, I think they are in a few different spots through out the years, but your is just like mine, so it is on the pass. side front wheel well (back side) Hope this helps

Rarely do our O2 sensors throw codes unless the blow completely. They start losing effectiveness at 50-60k though.

Maybe Techinfo could help with your codes?
http://www.bonnevilleclub.com/forum/...e=article&k=69

And as mentioned, ignore the 58 on any 92, regardless of engine.

well the care has 151,000 miles on it and I know nothing has been done since 90,000 miles or so. probably not before that either.
the car was my wife parents we got it at 118,000 miles for free and the got it when her grandma passed away so it has been family owned and those things have probably never been changed.
chad

I bet a good tune up would fix you right as rain. Most here use NAPA Belden premium wires and NGK TR55 plugs, that is what i have as well. Ac Delco is the only o2 sensor for you, and a fuel filter is a cheap and easy do it yourself thing as well.....

thanks for the tips!
beldon is life time warrenty on the wires right?

ngk plugs for better perfromance?

NGK makes the AC Delco plugs. Use either.

Does performance drop when the car heats up? That'* alot of miles if it'* the original catalytic converter, particularly if your O2 sensor has been mucking it up. A backpressure test would confirm or rule that out, but I'd go with the full tuneup first.

Yes.......

They are proven to perform better (over other brands) in these cars (NGK in general). That or factory Ac Delco plugs, whatever you prefer....

no the performance doesn't drop off when the car heats up. It only runs crappy when the weather is nasty. It has been rainy and foggy and misty here all week and I think my plug wires are the culprit. I think they get condensation sitting on them over night and causing them to short out and when it heats up and burns the moister off it runs better but not great. I will start by changine the plugs and wires see how it goes then replace the o2 when I get paid.

thanks guys

Please note...

There is a post regarding possible oil observed in water when changing water pump on this car recently.