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Discussion Starter #1
I have been chasing my tail for 2 months on my 4.9 Elderado motor in my Fiero, it is the late model 4.9 that uses the dual O2 sensors. Running really rich and getting horrid gas mileage around 10mpg in town. To drive from Surrey to Van and back cost me $25 in gas. About 2 months ago I installed 2 brand new NTK O2 sensors. I notice on the scan tool that the O2 voltage is at a constant 444mv I talk to a couple of people and no one seems to really have any idea and one person said "that is just the way they are" so I left that alone, after all they were brand new O2 sensors. So I went on trying to find out why the dang thing ran so rich all the time. Car was so rich that it would burn your eyes at idle.

So today I bought 2 Genuine Delco O2 Sensors.( AFS23 ) I installed one and left the NTK in the other bank. I fired up the car and checked the scan tool. Sure as crap, the NTK stays at 444mv while the new GM one was constantly moving from 84mv all the way to 900mv so rapidly that the Dash mounted scanner could not keep up.

So I pulled the other NTK out and installed the 2nd O2 sensor from GM AFS23 and took the car for a drive, instantly the car was better, smoother, ran awesome, pull from idle to 4000 and part throttle was so much smoother. It was like a hole new car. Even the high idle issue I was having seems to have partly cleared up. I am so happy.

I hear so many people with bad gas mileage problems, cars running horribly rich. I can't help but wonder if that NEW O2 sensor is really doing its job.

This is just a huge heads up.

As for me, I am off to go driving around.
 

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Discussion Starter #2
Well I took the car on a double city run putting over 100 miles on the car yesterday.

Normally I would have burned through at least 8-10 gallons of gas.

But with the new O2 sensors, It was just a touch over 3 I am so happy. Car is finally getting the 30-32 mpg it is suppose to with the 4.9 and 5spd.
 

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A good case for AC/Delco parts. I have found this out on occasion when I went cheap. I replaced the O2 sensor on my '86 Fleetwood brougham with a Niehoff unit and after a year the power and mileage went into the toilet. Even a used Delco sensor worked better, so I replaced it with a new one. The car runs so much better an has some power and good fuel economy.

I would say diit of all Delco products from spark plugs to oil filters. Stick with them, and you will have no problems.

Mike
 
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