I have a 1993 S13 Hatchback with 24K miles.
The previous owner failed the smog check yesterday.
The result:
M1. 15MPH
HC: MAX 88 AVE 21 MEAS 28
CO(%): MAX 0.52 AVE 0.06 MEAS 0.08
NO(PPM): MAX 704 AVE 150 MEAS 775
M1. 25MPH
HC: MAX 53 AVE 13 MEAS 24
CO(%): MAX 0.50 AVE 0.05 MEAS 0.13
NO(PPM): MAX 738 AVE 136 MEAS 507
My friend help me to do the regular maintenance services after I brought the car.
We did:
Change engine oil and oil filter
Flush coolant and fill in 50/50 coolant
Clean fuel and change fuel filter
Replace air filter
fill up 91 Octane
I just smogged the car today and it failed.
M1. 15MPH
HC: MAX 88 AVE 21 MEAS 41
CO(%): MAX 0.52 AVE 0.06 MEAS 0.12
NO(PPM): MAX 704 AVE 150 MEAS 784
M1. 25MPH
HC: MAX 53 AVE 13 MEAS 31
CO(%): MAX 0.50 AVE 0.05 MEAS 0.10
NO(PPM): MAX 738 AVE 136 MEAS 432
How do I pass the NO(PPM) with 15mph? Any suggestion? Replace O2 sensor, catalytic converter?
Thanks!93 Nissan 240SX smog check help?Replacing the muffler will not help the emissions. The catalytic converter COULD be an issue, but at 24K, I rather doubt it.
Several things could be causing your NOx failure, but most likely either ignition timing is not correct or the EGR valve isn't operating properly. The fact that the car passes at the 25MPH test indicates that the cat is PROBABLY functioning well.
If there is an exhaust leak before the converter (exhaust manifold, exhaust header pipe, hole in pipe, loose O2 sensor etc.) the added oxygen will cause the NOx to rise.
Base timing should be at 10掳BTC, with the timing connector jumped. After adjusting the timing, remove the jumper. If 10掳 cannot be achieved, and the timing is advanced to something between 20掳 and 35掳 BTDC, chances are that the throttle position switch will require replacement and adjustment.
If these two areas are acceptable, then check the EGR valve function.
1) Warm the engine to operating temp.
2) with engine idling, apply vacuum to the EGR valve (not the transducer). The engine should stumble and run very rough or even die. If it does, then the valve and the ports are satisfactory. If the engine doesn't change, then determine if the valve is defective or if the passage is restricted.
3) Determine if the transducer is working correctly, and if the feeder tube for the transducer is clear, and that the rubber hose from the tube to the bottom of the transducer is not damaged or burned, or disconnected. If you follow through here, chances are you will find the cause of your wlwvated NOx.93 Nissan 240SX smog check help?Yes that is the EGR valve you are describing. Change th e O2 sensor if it is cheap depending on the car model. Cat should be good if mile is only 24k original miles. Only change as last resort as it can be a few hundred bucks to replace.
Checks for vacuum and exhaust leaks. Replace all vacuum hoses with new hoses just to be sure its very cheap to replace. Buy one of those bottles that claim the help you pass the smog. Follow the directions on the bottle. If you fail to pass you can get a refund from the company making the claim. You must read all the terms and small print and save all paperwork.
Always make sure when you bring it in to test that it is already at operating temp and not cold. Also check the idle and make sure that is correct as that alone can make you fail an emission tests. You forgot one biggie that doesn't cost much and can make the difference. Change the spark plugs and PVC valve and breather element if you have one. Good luck
