Failed emissions / high Nox
Thread Starter
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
Failed emissions / high Nox
Failed the Nox portion of the test here in Massachusetts. Hc and Co are well below the allowed limits. Installed a new EGR valve and verified the vacuum solenoid is working per my Helms manual. Adjusted the timing back to 2 degrees (was set at 8 degrees). Failed the test again with no change in readings. I am running a Catco #9118 main cat (installed last year) with no precats. Does anyone know if this cat is a "3 way, dual bed" unit designed to reduce Nox? I noticed some vendors list two different cats depending on whether you have precats or not. The 02 sensor was replaced last year also. The coolant temp runs about 190 degrees on the highway(180 thermostat), but it was at 224 by the time the inspector got it up on the rollers for the "cruise speed" test. I don't think 224 is too hot, but something is going on to make the combustion temp. hot enough to produce excessive Nox. The car runs perfectly with no stalling, surging, or any other signs of a malfunction. Next step is to hook up the Auto Xray scanner I just bought and look at some numbers. Anyone else out there have Nox issues? This is a totally stock 1987 engine with 123000 miles.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I'd put the timing back to stock. Engine temp is ideal for the test and since the a/c is off, it's going to run up to 226 before the fan kicks in. You might want to make sure the air pump is diverting to the cat - disconnect the hose to the converter and check for air after it goes closed loop. Verify the check valve is good by making sure that air is only flowing towards the cat. Otherwise, assuming EGR is working and it's got decent BLM's and an Integrator indicating that the mix is 14.7 to 1, I'd suspect the converter. I have no idea if your replacement is a dual bed, but as far as I know, all the OEM's were.
Team Owner
Joined: May 2001
Posts: 36,136
Likes: 2,511
From: ...tearing up the highways, one state at a time™®©
I failed due to high nox when the car was:
1. cold(er) than it should have been...
2. tester ran the car in too high of a gear (lugging eng instead of revving it)
Drove it till it was nice and hot, and retested in second gear, not third
at a diferent site...
1. cold(er) than it should have been...
2. tester ran the car in too high of a gear (lugging eng instead of revving it)
Drove it till it was nice and hot, and retested in second gear, not third
at a diferent site...
Le Mans Master
Joined: Jan 2003
Posts: 6,187
Likes: 309
From: SIMSBURY CT
St. Jude Donor '07 thru '25
Originally Posted by SS409 425HP
.................I am running a Catco #9118 main cat (installed last year) with no precats. Does anyone know if this cat is a "3 way, dual bed" unit designed to reduce Nox? ...............
I don't have my emissions results handy right now but I'm failing too with a new Catco #6__? converter, no pre-cats and headers. After trying a few things my next step is to get rid of the Catco converter. I think I'm going to try a stock main cat next.
Heel & Toe
Joined: May 2005
Posts: 17
Likes: 0
Smog Police
I live in California, and I recently haad my vert smoged by a smog test only location. It is ran and monitored by the state. The tests are becoming harder and harder to pass with the higher standards being laid down as law. I think the bench mark that the goverment is getting to is one of leaving the vehicle stock. I failed the first test, and second test with a hot setup. I could not afford to fail a 3rd time, so I de-tuned the motor going stock. Passed with flying colors. That was my fix. The down side to this is if I was to fail for the 3rd time, a referee would be stepping on my neck, and I would more than likely be on the California DMV hit list for another state certified smog only site. I don't want that lable, so be careful out there!
Thread Starter
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
Originally Posted by lticforce92
I live in California, and I recently haad my vert smoged by a smog test only location. It is ran and monitored by the state. The tests are becoming harder and harder to pass with the higher standards being laid down as law. I think the bench mark that the goverment is getting to is one of leaving the vehicle stock. I failed the first test, and second test with a hot setup. I could not afford to fail a 3rd time, so I de-tuned the motor going stock. Passed with flying colors. That was my fix. The down side to this is if I was to fail for the 3rd time, a referee would be stepping on my neck, and I would more than likely be on the California DMV hit list for another state certified smog only site. I don't want that lable, so be careful out there!
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Did I read your scanner post correctly; ie, the Block Learn is 155? If so, it's mega lean (actually, it should throw a code if it continuous). Assuming that's true, check your air pump circuit. If it's dumping air into the headers and not the cat, emissions will go to hell.
