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Discussion Starter · #1 ·
I have a lean condition that I'm trying to sort out.

I pulled the data from the OBD and made a nice graph of O2 sensor readings, maf, throttle position, and on and on.

The piece I'm missing is what should normal mass airflow be? At idle I'm showing somewhere around .5 to .7 lb/m. At full throttle run up to highway speed I get at most around 11.5 lb/m. That seems low. I figure about 9 or 10 lb/hp. I was expecting something more like 14 lb/m or so.

Does anybody look at the OBD data and if so what is normal for mass flow?
 

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Discussion Starter · #2 ·
Per the tech manual it's 2.5 to 5.0 g/sec at idle and 7.1 to 12.5 g/sec at 2500 rpm.

So my MAF sensor is working about right. My O2 sensors also both seem to be working right.

The car runs leaner at WOT so probably not an air leak.

Must be fuel? I'll have to borrow a fuel pressure gage.
 

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How lean? Are you watching the fuel trims by STFT and LTFT or wideband? First thing I usually do is smoke the intake and make sure there are no vac leaks. What year is it? if it's 00' up I would buy a new OEM 3l Maxima maf if it has more than 100k. I normally put a new primary Bosh 02 if it has more than 100k also. I consider the MAF and O2 100k maintenance items.
 
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