Failed Smog, need some ideas.
05-08-2008, 11:52 PM
#1
Failed Smog, need some ideas.
My car runs SUPER clean on the CO2, O2, HC and CO tests. Fails on the NO test big time, measured 956@15mph (419 allowed) and 1002@25mph (706 allowed)
High NO indicates higher than normal Cylinder temps. From what I can find, the number one cause of this is a faulty EGR, which doesn't apply to me, as I don't have one. Other causes could be carbon deposits, failing engine cooling system, too lean or rich, or too much timing.
I Seafoam my car every third oil change, run only 76 premium, my car runs super smooth, so I highly doubt I have carbon deposits.
My temp rarely goes over just under center of the gauge, unless it is 110+ outside.
Not sure about lean or rich, guess this might be a good excuse to convince the woman to let me get an LM-1 to test my A/F.
My timing is stock.
Things I have changed recently (within 600 miles):
MAF, front main o2 (my rear o2 was replaced about 20k miles ago), coils, plugs, cleaned the IACV/TB and changed the oil. Unplugged the battery for a few hours to clear the ECU of it's learning.
Not really sure what I can do to lower the NO, as the car seems to be running fine. The only thing strange I can find was actually pointed out by the smog tech, though I have doubts it is related, while he was warming up the car, he revved to and held ~2000rpm while in park, and it would randomly drop 500 RPM then climb back and hold for a few seconds and then drop again. Any higher than 2100rpm and lower than 1600rpm it would not do this. I confirmed this tonight and it does indeed do this in park but not in neutral, it also did not exhibit this in gear while on the smog dyno.
Any ideas?
High NO indicates higher than normal Cylinder temps. From what I can find, the number one cause of this is a faulty EGR, which doesn't apply to me, as I don't have one. Other causes could be carbon deposits, failing engine cooling system, too lean or rich, or too much timing.
I Seafoam my car every third oil change, run only 76 premium, my car runs super smooth, so I highly doubt I have carbon deposits.
My temp rarely goes over just under center of the gauge, unless it is 110+ outside.
Not sure about lean or rich, guess this might be a good excuse to convince the woman to let me get an LM-1 to test my A/F.
My timing is stock.
Things I have changed recently (within 600 miles):
MAF, front main o2 (my rear o2 was replaced about 20k miles ago), coils, plugs, cleaned the IACV/TB and changed the oil. Unplugged the battery for a few hours to clear the ECU of it's learning.
Not really sure what I can do to lower the NO, as the car seems to be running fine. The only thing strange I can find was actually pointed out by the smog tech, though I have doubts it is related, while he was warming up the car, he revved to and held ~2000rpm while in park, and it would randomly drop 500 RPM then climb back and hold for a few seconds and then drop again. Any higher than 2100rpm and lower than 1600rpm it would not do this. I confirmed this tonight and it does indeed do this in park but not in neutral, it also did not exhibit this in gear while on the smog dyno.
Any ideas?
Last edited by Regime; 05-09-2008 at 12:03 AM.
05-09-2008, 12:02 AM
#2
Since I already had the updated MAF in the car, I doubt putting a new one in would require a reflash, besides my ECU was replaced after they started updating the MAFs due to Technosquare frying mine when it was the test-donor for the Auto ECU tune that never happened...*******************************Roger... ******.
Last edited by Regime; 05-09-2008 at 12:19 AM. Reason: Roger was being a baby.
05-09-2008, 12:57 AM
#5
Idle RPM is perfect, 700 in park/neutral, about 550 in drive. Warms up from dead cold perfectly also, shoots to ~1500 for about 1 minute till the temp starts to rise. Then drops to said idle rpm's.
05-09-2008, 07:13 PM
#7
If I remember my days as an asst manager at Midas correctly (over 7 years ago)...
High levels of Nitrogen Oxide (not Nitrous Oxide) generally indicate an issue with the catalytic converter. Most exhaust shops can do a basic, but not always reliable, test to see if the cat is clogged. Most places will also do the check for free. Might be worth the time. Take your test results to the shop to look at also.
High levels of Nitrogen Oxide (not Nitrous Oxide) generally indicate an issue with the catalytic converter. Most exhaust shops can do a basic, but not always reliable, test to see if the cat is clogged. Most places will also do the check for free. Might be worth the time. Take your test results to the shop to look at also.
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