I have searched extensively on google and through these helpful forums but have not found a conclusive answer to my question, so I will venture to ask it here.
I recently moved from Utah to California and when I went to get the car smogged it failed the e-test for high NOx levels. It's an original California car that was out of state for a while.
1999 Cavalier, 2.2L
172,000 Miles
I've got newer plugs and wires on it. replaced the 02 sensor while I was in Utah with a Bosch universal from Autozone.
Fresh oil, year old coolant, had been sitting parked for around 20 minutes before they got around to testing it (if that makes a difference).
Readings were as follows:
%CO2 | % O2 | HC (PPM) | CO% | NO (PPM)
RPM | MEAS | MEAS | MAX AVE MEAS | MAX AVE MEAS | MAX AVE MEAS
15mph 1922 | 14.7 | 0.9 | 60 9 1 |0.53 0.03 0.01 | 459 57 742 | FAIL
25mpg 1905| 14.7 | 0.8 | 43 7 1 |0.51 0.03 0.01 | 746 50 674 | PASS
Any ideas? Could the 02 sensor have anything to do with this, since it was not a California OEM 02 sensor? Maybe the cat. is just worn out I know that there's no EGR, which is what they tell you to look at for a lot of cars with this problem. Could it be a dying fuel pump. The engine runs fine, no hesitation, never dies, runs smooth. Also, someone said to look at the fuel pressure regulator valve.
I am out of work and can't afford to pay a mechanic $250 just to take a poke at it. I would really appreciate a little guidance from some of you more knowledgeable types.
Thanks in advance.
bosch o2 sensor are junk, plain and simple. get an ac delco unit from a dealer. what brand and gap plugs? hows the air filter?
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autolite platinum, factory specified gap. Air filter is new within 5k miles. How much does an ac delco o2 sensor run? Also, it was my understanding that a failing o2 sensor causes the engine to run rich, not lean. From the emissions report, the engine is definitely running lean (such low CO and HC but high NO). Am I mistaken in this understanding?
Again, thanks for any help.
You could try some seafoam.
sensor probably has not failed, its just that bosch o2 sensors are that bad. try ngk or delco (made by ngk) plugs. seafoam could help, as could cleaning your throttle body and IAC.
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Does the 2nd o2 sensor (after the cat) make any difference in this equation, or should I only worry about the o2 sensor on the exhaust manifold? I was told that autolite plugs were the oem. Are they NGK after all? I already seafoamed the car so I guess I'll clean the throttle body and IAC valve before I test again. Any recommendations of throttle body cleaner?
You guys are really helpful.
autolite plugs are not oem in anything. our cars take delco plugs stock, and in 99 they were double platinum. the rear o2 sensor only checks to make sure the cat is working, it doesnt do anything else. as for throttle body cleaner, crc makes a great product. buy two cans.
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A lot of O2 and NOx leads me to believe a lean situation. I would try a AC delco O2 sensor. And maybe run a seafoam type product through it to clear out some of the carbon in the combustion chanber.
I cleaned the throttle body really well, cleaned the MAP sensor with a clean rag and compressed air (wasn't sure if it was one of those sensors that gets screwed up if you use solvents on it) cleaned the idle air control sensor.
I ordered an AC Delco O2 sensor. The car doesn't seem to run any better or worse but we'll see what the emissions results are soon enough.\
Where is the mass air flow sensor on the cavalier? It's not the sensor on the air intake hose, is it? If so, I cleaned that with MAF cleaner.
I got it smogged again, this time at a test only station. The numbers were almost the same but the tech gave me a heads up that it sounds like I have a vacuum leak, but he could not identify the source. Which vac line would be the most likely culprit, and are there any besides the 4 lines that run to the throttle body? I'm not a mechanic so I don't have a ton of experience (I just learn as I go when things break and this would be the first vacuum problem I've ever dealt with). Any advice would be greatly appreciated.
its got nearly 200K on it! What do they expect you to do? Would the denatured alcohol help?
Nathan Taylor wrote:I got it smogged again, this time at a test only station. The numbers were almost the same but the tech gave me a heads up that it sounds like I have a vacuum leak, but he could not identify the source. Which vac line would be the most likely culprit, and are there any besides the 4 lines that run to the throttle body? I'm not a mechanic so I don't have a ton of experience (I just learn as I go when things break and this would be the first vacuum problem I've ever dealt with). Any advice would be greatly appreciated.
Yeah a vacuum leak would do it. I'm not too sure on the 2200 but maybe the vacuum line that goes to the fuel pressure regulator.
You can hear a high pitched whistling sound from the source of the leak, to find where it's leaking from move the lines around and see if the tone changes.
