Engine Stumbles when warm, o2 sensors changed

[tab1217]

So, my car started running like crap once it reached operating temp. Rough idle, stumbling, almost like backfiring sounds, did not go away at WOT. It was suggested that bad o2 sensors could cause this. 80 bucks and 3 hours later, the problem didnt go away. Now, my car wont start intermittently, 12 volts at the battery, but as soon as I turn the key to Acc, voltage drops to 8 VDC. If I charge the battery for an hour or so, the car will start and the voltage at the battery reads 14 volts. If you let the car run, the stumble problem occurs when the temp gage reaches the halfway mark (210 degrees i think?), so my question is, could a bad battery cause the engine stumble problem?? It sounds dumb when I hear myself ask it, but I dont know what to do. The thing is, the car ran perfect when I parked it for the winter, so other than the battery taking a crap I dont know what could have gone wrong just sitting in the garage? Sorry for the novel, but im clueless.

[Fbomb]

Sounds like a short somewhere.

[98blackbeauty]

My guess is alt. is bad, not charging battry and/or battry probably has a bad or weak cell now. If I am correct the temp has nothing to do with it its time related cause your running on battry with no output from alt. What does volt gauge read when running? check it at battry and pos lug on alt. should read 13.5 to 14.0 volts.

[Fbomb]

Could be a short in the alt. drawing power when the ignition is switched on. Leave it on for a bit and see if the alt. gets warm.

[tab1217]

My guess is alt. is bad, not charging battry and/or battry probably has a bad or weak cell now. If I am correct the temp has nothing to do with it its time related cause your running on battry with no output from alt. What does volt gauge read when running? check it at battry and pos lug on alt. should read 13.5 to 14.0 volts.

I cant recall the scale of the gage, at work now, but I know it almost red lines, it goes to the last line before the red on the top side of gage.

[sman]

Thats about where mine runs IIRC, deff more than half way across the gauge.

[tab1217]

so, when i got home today I checked the battery voltage. 12.7 volts, turned the key, started it right up. ran it for 2 minutes, turned it off, tried it again, wouldnt start???? just the annoying "clicking" noise and battery only read 11.6 volts? Im hoping this weird starting, not starting, is related to the "runs like shit when warmed up" problem. These cars are like Stonehenge!

[98blackbeauty]

I'm still thinking Alt. is bad.

[meissen]

My car never ran rough, but it does sound kinda similar to the problems that I was having. I never found out 100% what was wrong with my alternator, all I know is that it didn't work right and it was causing me to have problems starting my car and was draining the battery. I could literally start my car one minute and then the next minute it would just click like the battery was dead.

[shawnc16]

Check your wiring harnesses. I've seen it many times where a mouse or rat chews the wiring up. It sounds like you had/have it stored so it always a possible cause. From there. 02 would cause the issue at an idle or cruise but not at WOT because the you are then in OL (open loop) A bad battery could cause an issue obviously if yur charging system is only allowing 8 volts, thats gonna cause all sorts of gremlins. I can't diagnose the issue over the internet but at least provide some decent insight. The intermittent starting leads me to believe you have an issue with ignition or fuel..

[tab1217]

I'm still thinking Alt. is bad.

I thought that too, so yesterday when i got home from work, it wouldnt start. Charged the battery for a hour, started right up, then I disconnected the positive from the battery. Car stayed running, had 14.9 VDC at the lugs where the commons and grounds connect. So.....Alt Good? Which made me think bad battery, but i checked it this morning (positive clamp off all night) friggin thing had 12.7 volts?? Could the battery be drawing the voltage down when the car is running?

[meissen]

Put the wiring back together, let it sit for a few hours, and then measure the battery posts again. If the regulator is going bad, it'll slowly draw the battery voltage down.

[JoeliusZ28]

a lack of voltage when running will definitely make the car sputter and run bad. The car needs full power to make good spark.

[98blackbeauty]

Its the chicken or the egg first routine. Alt can intermittantly have diodes short out and draw current and battry down. Battry can have a cell that shorts out and draws a lot of current from alt.
What Brian said is easiest way to separate the 2. OBTW is the battry a wet cell and if it is did you check water level?

[tab1217]

Had the battery tested. It was bad, replaced it, car started right up but ran like ass at operating temp still. Its like at 190 degrees it starts happening. After it starts sputtering and surging real bad if i shut it off and try to start it right back up it makes a HORRIBLE starter sounding kind of noise and wont start. You can smell fuel under the hood after you shut it off. Im going to try and change the water temp sensor in the pump this afternoon? Should I use teflon tape on the sensor threads? And seriously, how much/how fast is coolant going to come out of the pump when I remove the sensor???