96 Maxima O2 problem?

I have a 96 Max with over 285k miles. I have never really had many issues with it beyond the usual maintenance and wear and tear. However, for the last 3 years, almost all of my emission sensors have been replaced. I thought I was through with all that for another 200k when my "Check Engine" light just recently came back on. It was 0503, the RH Heated O2 Sensor.

I purchased the normally $80 part online for about $50. It was an SNG sensor. I replaced it, reset the computer and drove. I also replaced my fuel filter and added a short-ram intake kit all on the same day. Almost a week later, the light came back on. It was the same code. I cleared it, and it came back on the within miles.

I have reset it a few times. Since all of this, my car has been getting less MPG, from about 27MPG to 18. Moreover, it has now started to hesitate when I am accelerating from a stop or from less than 20mph. It is almost acting as if it is not getting gas or something.

It drives fine on at highway speeds. It accelerates a little faster to 60, 70, 80 and so on. In addition, I have been able to drive at

80, 90 and even 100 without the car going over 3,000RPM. I attribute that to the air filter mod, but I could be wrong.

Therefore, Nissan community, what do you think the problem is? Is my new O2 sensor bad? If I had bought it locally, would you have suggested I returned it already? On the other hand, is it the mod or something else?

  • I will let you all know that I am no expert but I have done most of the work on my car (CV axle replacement, radiator and such), so I am no slouch. However, I am lost on what I should do next.
Reply to
Charlie 3
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Have you changed the coolant temp sensor? When that sensor goes bad you never see a code. The car's milegae gets worse and power gets a bit weaker. Before you replace the O2, I would try that.

Also, once changed, the ECU needs 2 or 3 tankfuls to relearn its feul curve according to the readings that its now getting from the replaced temp sensor.

CD

Reply to
codifus

Not true, if the ECM detects a problem with the coolant temp sensor it will flag a code

Reply to
NissTech

I should clarify then, and say that when the coolant temp sensor starts to fail, but not quite, the ECM will not pull a code. Symtpoms of a dying temp sensor are the bad gas mileage, some loss of power, and the car never quite getting to operating tempurature.

The O2 sensor is that way as well. I've replaced dying ones that never pulled a code and the car just came back to life with the new one.

CD

Reply to
codifus

SO put the stock airbox back on. You should only create ONE problem at a time! (-:

-SP

Charlie 3 wrote:

Reply to
Speedy Pete

You're saying that the air filter mod changed the RPM to MPH ratio? It wouldn't.

Reply to
Chuck Tribolet

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