Help, Failed Smog NO too high at 15 mph ONLY

[Jmrec100]

My 1999 Cavalier failed smog at the 15mph test. The CO2, HC, CO were all low - not even close. But the NO at 15 mph failed. The 25 mph test had no problem. NO @ 25 mph measured 144, Max allowed was 746. So well below. NO @ 15 mph measured 752, Max allowed was 459. So It failed badly. Any suggestions? I first thought the Catalytic converter BUT, it passed easily at 25mph. So maybe the O2 Sensor? Any suggestions? Thanks, I drive it mainly on freeway to work and back. I drive alot of miles.

[Jmrec100]

Any Suggestions? Is it possibly that the engine was getting too hot and producing NO? I noticed that the temp sensor to turn on the fan doesn't trip until the temp gauge reads 3/4 or more on the temp gauge. Seems a little late? So I turned on the AC to run the fan during the test. It may have put too much of a load on the engine for the test. So I have 3 things I may try. Let me know if it sounds reasonable. 1) replace the temp sensor again. I replaced it once before because the fan wasn't turning on at all. or ,,,,, 2)wire the fan to be on at all times. And retake the test. or ................... 3) Add in another generic aftermarket catalytic converter (about $100) to reduce the NO readings. . In my other car, 1989 Isuzu, if it failed smog, I just replaced the catalytic converter and it passed it no problem. The older catalytic converters were simpler and not so complicated as the newer ones after 1995. Adding a 2nd cat could help the smog test? Other suggestions would be helpful ! Thanks again. Anyone else having smog problems. My engine has about 80,000 miles on it.

[OverAllComa]

Have you considered just doing a full tune-up?

Oh yeah, and don't turn on your AC for that test. Bad idea.

[Jmrec100]

Tune-up being spark plugs, new wires, air filter, oil change, etc. Put in a new catalytic converter. No change. Next try to see if the guy will run the test in 2nd gear. The rpm's will be higher like at the 25mph test. May pass then. If he won't do it, then he suggested a clean-up procedure that cleans out the combustion chamnber etc... Its a treatment where a cleaning solution is dripped in and clean off the old carbon etc... Seems next attempt. Can't believe the new catalytic converter didn't lower the NOX. No change... hELP. I did set the fan to be on all the times to keep the temperature down And not run the AC>

[Young Chuck D]

around this time i would stop half assing and take the vehicle to a mechanic who will determine my problem for very cheap if not free

but thats just what i would do

[Jmrec100]

Problem solved. I tried one fuel system clean at a shop. It didn't work. Found another shop and he ran his special fuel cleaner. Took about 20 minutes. He told me don't pay him yet until the car passes. When it does, come back and pay him and tell him the results. He said if it doesn't work,I don't have to pay. He told me to take it right over to the smog place right after the treatment. No running the car to clean out the garbage the fuel system treatment would clean and break loose. IT PASSED UNBELIEVABLY LOW , near nothing. Went from 700's to something like 30.
Im a happy guy.

[Young Chuck D]

did he let you watch while he fixed it?


he probably used voodoo..

[Jmrec100]

Yes he did. He told me after several times trying to help cars pass the new NO standard, he came up with this solution. I was there talking with him the whole time. From tearing down his share of engines, he related that to tell that a car blew the head gasket is that its the cleanest part of the head. Water vaporizes quickly with heat in the engine and it basically blows off all the old carbon etc.... His concoction was mainly water and some other stuff. I could probably guess what the other stuff was if I went around looking at different additives. Anyway, it worked. After 20 minutes running his mixture through my car, I drove straight across the street, waited in line about 15 minutes with the car running and the fan rigged to the on position. It was miserably hot that day I remember too. My turn to run the test -It passed NO Problem at all....
Anyone in the SW Riverside area of Ca who has this smog headache should go to this shop....
His "voodoo" medicine treatment works...