Car Running Worse With New 02 Sensor

[HonetRaider]

First of all, hello everyone. This seems to be a very informative board, and I'm looking forward to learning and contributing.

Here's the story. I have a 1999 Prizm with 150,000 miles on it. The car has been dead reliable. I have been driving the car with a check engine light on for the last 2 years. I knew it was the primary 02 sensor (upstream). Recently, I decided to go ahead and replace it since the light finally annoyed me.

I replaced the 02 sensor with a Bosch unit. The check engine light went away. Beautiful. However the car started running strangely. It would stutter and skip a few beats when starting from a stop. It would even hesitate to shift (3 speed automatic). I would have to play with the accelerator for the car to "catch" and accelerate/shift normally. No codes were thrown. One thing I did notice was at wide open throttle, it always caught and accelerated like normal.

At this point, I figure it is ignition related. Replaced plug wires and plugs. Same problem. The only thing that had changed between the car running right and not running right was the 02 sensor. I tried unplugging the battery overnight. Problem is still there. At this point, I figured I got a bad 02 sensor. So I returned it and got another brand new sensor. Same problem. At this point, I unplugged the 02 sensor just to make sure I wasn't going crazy. Check engine light comes back on, and the car runs beautifully again.

Any ideas? Any help and input is appreciated.

 

[Muhammad Ali Khan]

I dont know if your car have the MAF sensor. If it is there try to clean it with MAF sensor cleaner (dont use other cleaners). The ECU stores the data while you drive. As you were driving with out the sensor so the best readings are stored. You need to drive it a lil bit to see the effect. The data should be erased as you unplugged the wires overnight. May be its not.

Check also your O2 sensor in the exhaust. If you have the scan tool which can be connected to your phone try to see the readings of the sensors and compare.

 

[HonetRaider]

Thanks for the response. I believe my car has a MAP only. I did clean that with some MAF cleaner. It seemed to help, but maybe that's just placebo. The problem is still there, it just no longer happens every time I accelerate from a stop. Now, it happens every 4-5 times.

 

[CarInOrder]

Be sure that when you clean the MAF you get both parts of the sensor. I had a post talking about this here. The guide that is linked has some good pictures showing exactly where to clean on the MAF sensor. Otherwise you can think you have fully cleaned the sensor, but one part of it will remain dirty/faulty.

 

[Muhammad Ali Khan]

CarInOrder he doesn't have the MAF sensor anayway.

 

[CarInOrder]

Whoops, right you are. They came in year 2000. I just saw MAF and know that I mis-cleaned the sensor the first time. Anyway, apologies.

The ECM does use the upstream O2 sensor to monitor and adjust the air/fuel ratio. Since you replaced two O2 sensors, I would look at the wiring and mating connector and the air supply to make sure air can move over the inside part of the sensor. Also, some models are equipped with an O2 sensor heater, so you can make sure that is functioning correctly also.

 

[HonetRaider]

All,

Wanted to thank everyone for their responses.

I wanted to update this thread. The more I have driven the car since the 02 sensor replacement, the better the car drives. It has been a week since the stutter has occurred. This is strange considering I had unplugged the battery for 20 min after the install in an attempt to "reset" the computer. Does the duration of time that the battery must be unplugged for the reset to occur exceed 20 min?

 

[CarInOrder]

Thanks for the update and glad to hear the stutter has gone away. I don't believe the duration of time the battery is unplugged has any effect (meaning the reset should happen as soon as you unplug the battery).

 

[Muhammad Ali Khan]

We are glad that your problem solved. As I told you ECM stores the data as you drive.

Once I remember having a honda civic and after cleaning the throttle body the rpm goes up and down from 900 to 1300 and its very difficult to drive. But the key is to drive for 20 minutes on a straight road at 80 kmph and dont push or release the accelerator. The speed will go slightly up and down unless ECM stores the best readings and you will be fine then.

 

[HonetRaider]

Yes, you were right from the get go Muhammad Ali Khan. It is nice to drive a car without a CEL again. It has been a long long time.

 

[Luis0522]

I see your update but I'm positive your problem was with your Bosch 02 sensor. I too drove my car for 2 years with the check engine light on (2001 Toyota Corolla), and my problem was an 02 sensor bought a Bosch from my local auto parts store and installed it. My vehicle then had hesitation from a stop at the time I worked at a Toyota dealer as a lot porter and spoke with a master technician about my concern he assured me it was the 02 sensor. For some reason most Toyota don't seem to do well with aftermarket 02 sensors they just don't work well together switched it back to my old one and the hesitation stopped. Bought a factory 02 and my car ran fine from the beginning after installation and my light went away.

 

[HonetRaider]

I put a new Bosch one in. That thought did cross my mind though, since the sensor itself did look different from the OEM sensor. I wonder if Toyota still stocks this sensor. Do you recall how much you paid for yours?

 

[Luis0522]

I paid about $140 something. I did work at the dealer so that was with employee discount. Kind of pricey sensors but I have yet to find an aftermarket one that will let me car run right. So it is more money but you shouldn't have any problems with it once installed. Well worth it in my opinion. And when I went to return the Bosch, store told me they couldn't take it after it's been used but I then explained to them that Toyota told me the sensor is causing my hesitation problem and the sensor was no comparable with my car. No more questions asked they took it back and refunded my money.

 

[Luis0522]

Compatible*

 

[HonetRaider]

Even the bosch sensor was $100 from autozone. I did get 50% off though, but if $40 is worth it to make sure everything is working properly. The Bosch unit in there now seems to be working fine, but if it starts acting up again, I'll fork over the cash for an OEM one.