MaximaZero

Before I get to the current problem, here's a recap of what happenned leading up to where I am now.

Around July, my friends and I put on a y-pipe on my Cali-spec VQ30 and in the process broke one of the bolts that connecting the front precat to the exhaust manifold. I decided that I would have to take the exhaust manifold off one way or the other to get that fixed, I decided to swap out to a Fed-spec front exhaust manifold.

I took it to Matthel's shop to get that done, but forgot that Cali-specs have one more O2 sensor than the Fed specs. For the time being, we installed the exhaust manifold with one O2 sensor and left the other one zip tied under the car until I got a chance to get another O2 sensor bung welded into the y-pipe.

It drove fine, and I was very busy so I drove around like that for a few months. The only problem I could tell was the CEL, so I put it off. Well while I was out of town, my dad decided to take my car in for a smog check not knowing it would fail with the CEL on. The car passed all the emissions tests, but failed because of the CEL.

Since I had to get it re-tested, I finally took my car in to get the O2 sensor bung welded in. Everything looked OK. I reset the ECU and drove around a few hundred miles, and it didn't come back on. I figured everything was OK, so I brought it back in to get re-tested for emissions.

I failed AGAIN even though the CEL is cleared and the O2 sensor is installed.

So now I'm stumped. I don't understand why the car would pass the sniffer test with the O2 sensor unplugged, but fail with it in.


So now...

I figure that it's gotta be either the O2 sensor has malfuntioned, or cat failure. Is there anyway for me to diagnose if it's either one of those? I would put the stock y-pipe on, but that would require drilling out the broken bolt in my Cali-spec exhaust manifold and swapping it back on. Anyone have any ideas?

sascuderi

Exactly why did it fail the second time. What did they say?

Maybe it failed becasue of a "not ready" status of some of the parameters? When you re-set the CEL it can take 2 months of daily driving to get a "ready" status on all the parameters sometimes.

Of note, in NJ for a 2000 they will pass you if two parameters are "not ready" as long as the CEL is off.

KabirUTA13

iTrader: (11)

cooda gotten a simulator to get rid of those secondary o2's

MaximaZero

It failed on NO emissions. They measured 720 PPM @ 15 MPH. The max allowed is 424 PPM with an avg of 57 PPM @ 15 MPH. It passed the NO test at 25 MPH with 654 PPM out of an allowed 711 PPM (average of 50 PPM). This is really weird because before the O2 sensor was plugged in, I scored 274 PPM @ 15MPH and 189 PPM @ 25MPH. CO2, O2, HC and CO measurements are about the same if not better after the O2 sensor was plugged in. Only NO emissions went up.

MaximaZero

Bump for the day crew.

GreenSeMax

that's weird.......but i was under the impression it was unlikely to pass a sniffer test. I passed with a y-pipe and CM test pipe, but in ct they only do a plug in, and i had no cels and no stored cels, so it passed even though it smelled like a pro-stock while they tested it haha. My only thought is that some people have passed a sniffer when you fully heat up the main cat, and take it right to the testing center, but i've never hear of someone passing a sniffer w/o a main cat. I can't really understand why the 02 being out passed, and didn't when it was installed??????????????????

speedlude2000

I had an issue during my emissions test here in MA. I had just finished replaced the 4 O2 sensors (one of them twice due to a defective one) and then I cleared the CEL (I have a scan tool) and went to get the sticker the next day. The tech told me that I needed to drive the car for a week before I could get the sticker. I had driven maybe ~50-60 miles, but he said it needed a week.

How long after you reset the CEL and drove the several hundred miles, did you go for the test?

MaximaZero

I drove it for 2 weeks and about 400-500 miles before bringing it in.

foodmanry

iTrader: (15)

Was your car warmed up prior to the second test? Reason I ask is because the y-pipe removes one of the pre-cats. The pre-cats keep emissions down during initial start-up of the car. Hence...it should be in operating temperature before testing.

If your car was warmed up, then I would have to say it is the O2 sensor. I would just replace it. They are relatively inexpensive.

Honestly your y-pipe shouldn't have an effect on emissions as long as your car is warmed up.

MaximaZero

I drove it for about 30-40 minutes prior to the smog check, but then had to wait 15 minutes before the tech could get to me. Would that be enough time for the cats to cool down to a low enough temp to not be effective?

Omegasrk

iTrader: (1)

I feel your pain in trying to pass the Cailifornia Smog Check with your mods. There is still hope for your car to pass. Please read my post found at the West Coast Forum:

http://forums.maxima.org/showthread....34#post4893634

Hopefully this might help you and any other people with similar mods to pass smog check.


steve...

foodmanry

iTrader: (15)

Probably not...BUT maybe....when I did the smog with my y-pipe and I had to wait I just left the car running the whole time.