Possible oxygen sensor power problem? 95 prizm


ellagrrl
10-24-2009, 11:01 PM
My 95 geo has been having intermittent episodes of slow acceleration, often when going up hills, and possibly related to heavy rain. It just feels like the car has half power, and only makes it to normal acceleration if I put the pedal all the way to the floor. The loss of power feels unsteady, like with the pedal all the way down, the car will start to accelerate more and then ease off for a few seconds and then on again. I would also notice that sometimes the gas mileage would jump by 5mpg for a tank, then go back to normal for a few tanks, then jump again.

Yesterday, the o2 sensor underneath the car (that plugs into the exhaust) fell out while I was driving on the highway, and started dragging on the road. My check engine light didn't go on when this happened (i think it's supposed to). My dad put the sensor back in, but he doesn't really do things very carefully or by the book. Driving it after it was put back in, it seemed to have better power than usual. Then tonight (its raining) it had a pretty bad episode of the loss of power again, first time in a while.

Does anyone have any experience with a loose 02 sensor connection or a failing sensor--does it sound like this would fit that problem? Should the check engine light go on if a sensor detaches?

Thanks!!!

lingam
11-02-2009, 04:37 PM
If your O2 sensor was loose enough to fall out your check engine light should have gone on at some point especially after it fell out. If it dragged on the street the threads were probably damaged. I'd check to see if the sensor was on tight.
Losing power on hills could caused by a bad fuel filter. Loss of power in the the rain I've seen in my Prizm if heavy rain wets the spark plug wires and distributor. It has happened in very heavy rain. Replace the spark plug wires (use silicone dielectric grease on spark plug boots) and look for carbon "tracks" between distributor terminal inside distributor cap. If there are tracks or terminals are worn replace the distributor cap too.
Hope this helps.

ellagrrl
11-02-2009, 05:41 PM
If your O2 sensor was loose enough to fall out your check engine light should have gone on at some point especially after it fell out.
The check engine light definitely did NOT go on, and the 02 sensor definitely was completely detached and dragging from its cables. I don't really know what this would mean re the 02 sensor or the check engine sensor.

Losing power on hills could caused by a bad fuel filter. I already replaced both the fuel and air filters, and the problem hasn't changed. The problem happens both in the rain and not in the rain, and sometimes on hills and sometimes not--i.e. I can go up the same hill 2 days later and be fine, when I almost couldn't make it up 2 days before. This is what makes me think that it is related to something connecting or disconnecting frequently.

lingam
11-04-2009, 06:32 PM
I'm more concerned that the check engine light didn't go on. If that system isn't working then diagnosing the hill/rain problem would take longer than it has. Why don't you take it to Autozone? You can plug in one of their diagnosis units for free and see if you get any codes.

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