Lean Conditions-Long and Technical - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Pacman · 12-24-2006, 05:40 PM

Story-I put my car on the smog machine at school to complete some labs and saw that the numbers showed VERY lean conditions. My emissions are off the charts. My NOx (200ppm-idle, 1150ppm-2500 RPM), HC's are very high, CO2 is about 12.5% and A/F ratio is about 19.5:1-22.5:1. I went to data screening and saw that my short term fuel trim and long term fuel trims are near optimal for being a ODBI car. But, for them being near optimal, my O2 Sensor is not switching lean/rich like its suppose to.

I performed a fuel volume/pressure test and came up with good volume but low pressure. Pressure is about 29PSI regulated, from my understanding, its suppose to be at like 40PSI. I've done nothing to the fuel system except new lines and a 300ZX TT Filter.

-Now, does the Z filter have a different filtering element then the stock 240SX filter (like a tighter weave or different filtering element that could cause a restriction)?
-Is there any other fuel pump tests I can perform using a voltmeter? I don't have the gauges or vacuum pump access since I'm out of school for the holidays.

I just put this motor in since the other motor started burning oil (possibly from the lean conditions?). I don't want this motor going out as well. I commute about 650 miles a week and its my only car. I'm almost to the point of selling since its benn a headache for the last 2.5 years of owning it; just one thing after another.

12-24-2006, 05:40 PM	#1
Pacman Zilvia FREAK! Join Date: Sep 2003 Location: Ohio Age: 37 Posts: 1,149 Trader Rating: (1) Feedback Score: 1 reviews	Lean Conditions-Long and Technical Story-I put my car on the smog machine at school to complete some labs and saw that the numbers showed VERY lean conditions. My emissions are off the charts. My NOx (200ppm-idle, 1150ppm-2500 RPM), HC's are very high, CO2 is about 12.5% and A/F ratio is about 19.5:1-22.5:1. I went to data screening and saw that my short term fuel trim and long term fuel trims are near optimal for being a ODBI car. But, for them being near optimal, my O2 Sensor is not switching lean/rich like its suppose to. I performed a fuel volume/pressure test and came up with good volume but low pressure. Pressure is about 29PSI regulated, from my understanding, its suppose to be at like 40PSI. I've done nothing to the fuel system except new lines and a 300ZX TT Filter. -Now, does the Z filter have a different filtering element then the stock 240SX filter (like a tighter weave or different filtering element that could cause a restriction)? -Is there any other fuel pump tests I can perform using a voltmeter? I don't have the gauges or vacuum pump access since I'm out of school for the holidays. I just put this motor in since the other motor started burning oil (possibly from the lean conditions?). I don't want this motor going out as well. I commute about 650 miles a week and its my only car. I'm almost to the point of selling since its benn a headache for the last 2.5 years of owning it; just one thing after another.