Recently my 96 Max AT sometimes stalls at stop sign/traffic lights and CEL light is on, sent to Firestone, was told MAF sensor needs to be replaced, and they quoted me $670 for the job. Checked code, there are two codes, 0102 and 0304 which point to MAF sensor and knock sensor. I cleaned MAF sensor, it didn't do anything, the code came back again so I ordered MAF sensor and KS from eBay and replaced both on Sunday. The old KS is no good, got cracks on it. I also cleaned throttle body and clear the codes. Then a day later, the CEL came back on, check the code again, this time, it is 0303 and 0304, front left O2 sensor fault and knock sensor fault. This doesn't make sense, I just replaced KS so I wonder if it is really KS problem or, maybe KS code just piggy back on O2 code.

The car does not stall anymore, but the engine is not smooth as it should be, acceleration is not as quick and I can feel there is a push when up-shifting from first gear to the second.

Should I also go ahead to replace front left O2 sensor or my replacement KS sensor is a bad one?

Speaking of O2 sensor, would ebay ones be any good:
http://www.ebay.com/itm/New-Nissan-Maxima-Infiniti-I30-J30-O2-Oxygen-Sensor-/330687471067?fits=Year:1996|Model:Maxima&hash=item 4cfe825ddb&item=330687471067&pt=Motors_Car_Truck_P arts_Accessories&vxp=mtr
or
http://www.ebay.com/itm/New-O2-Oxygen-Sensor-Before-Catalytic-Converter-Nissan-Frontier-Xterra-2003-/230798192158?fits=Year:1996|Model:Maxima&hash=item 35bca4ee1e&item=230798192158&pt=Motors_Car_Truck_P arts_Accessories&vxp=mtr

Thanks.

 

There are certain parts you dont buy off ebay, the MAF and 02 sensor are two of those parts

 

New O2 from rockauto for $50 shipped. KS is a piggyback at this point.

 

^^^ Exactly. The knock sensor code has a tendency to falsely show up with other codes. Take care of the O2 and there is a good chance the ks code will disappear.

 

Are two front O2 sensors the same or interchangeable?

 

The two upstream (front) O2 sensors are the exact same interchangeable part while the downstream O2 sensor after the CAT is different. I got both my upstream O2 sensors from www.rockauto.com 3 years ago and they've held fine.

 

Your new MAF is metering the air differently, correctly we hope.
This has now opened up a new issue with an o2. Makes sense actually.
The KS code, as previous mentioned, does come up with o2 codes.

Replace the o2, clear the codes and see if any codes come back.

 

also +1 for not letting Firestone do that RIDICULOUS over priced labor. I know that included core charges for the MAF but still. All you need is a screw driver to change it. Literally just a screw driver.

I hate that Autoshop chain with a PASSION.

 

OK, ordered O2 sensor.

 

O2 sensor replaced. The bad one has a lot of black carbon residue on it. Cleared the code and CEL remains off for few days. But, there is still a problem with the car, when pulling from stop, sometimes it hesitates, the gas peddle feels heavy. Cold engine is doing a little better. What else should I look?

 

general tune up

 

I plan to change spark plugs hope that would help. Went to check the code again, 0304 KS code still comes up.

 

By itself? Did you use a reader? Or pull from ecu?

 

I pull the code from ECU by reading how many times of long pulse and short pulse of the CEL light.

 

Iirc if you pull from the ecu it will always show ks. Even by itself

 

Yesterday I checked vacuum leaks with can of Carburetor cleaner, found no leaks. Checked TPS sensor, 0v from pin one but 5v from the connector, low and high om readings seem to be fine. Does this mean TPS need to be replaced?