Failed Emissions: Need Suggestions

[Red97GTP]

Ok, I went for my emissions test on my GTP today and failed. Now, for those of you who know about these cars, I have an aftermarket computer from DHP installed. Unknowingly, the computers diagnostic file was not accessible. So, they did a regular test on the vehicle and I failed because of too much NOx. I was at 1.7823 grams/mile and the limit is 1.5000 grams/mile. Basically, my question is, should I just put the original PCM in and go back to have them test that (I know the diagnostic file is accessible?) Do that, and go to a different test station where they won't remember me or the car? Or, just wait until next week? Any advice is greatly appreciated!!

Brian

[hrsp]

sell me your car for cheap?

i would try what you said with the pcm...but i dint know shiit about emmisions

[Lash]

You HAVE to pass the sniffer test now. Since you failed on it now you have to pass on it. It's already in their records. They wont even bother plugin it in and checking the diagnostic file now. They'll just throw it on the rollers right away.

[Red97GTP]

I wish I would have know about that before hand. In that case, what the hell is N0x anyways. How can I go about getting that resolved to pass?

[RanJer]

NOx = Nitrogen Oxide

in the past for me its usually been a bad o2 sensor or cat. but i never touched a computer on a car so.. yeah.

[98whitegpgt]

still got a cat? got a stock pcm? Ide try to put the stock pcm in and try again. The dhp adjusts fueling and all kinds of stuff.

[Cryptic]

do the normal stuff... new O2 sensor, plugs, wires, air filter...

I replaced mine at 100k just becuase.... you'll get better milage

[Feature Pony]

throw in 4 bottles of heat and 93 octane gas, drive it about 30 mins before taking it in.

[BAD LS1]

High Nox is from running to lean actually.

Wonder what your LTFT's are at or around idle....

[Red97GTP]

I have a new cat on there, and do have the original PCM.

[BAD LS1]

You just need to find a way to richen it up in closed loop to solve all your problems. The cat is taking care of Co and Hc already...

It might get worse with the stock computer... it could make it run worse and send the other readings off in the wrong direction. This is where people get screwed on mail order type tuning, but the L67 guys didnt have much options other than this DHP computer until recently.

Its funny taking my camaro in, all lumpy as shit stinking like and old school bus... passes the plug in test with flying colors lol

[animal]

You just need to find a way to richen it up in closed loop to solve all your problems. The cat is taking care of Co and Hc already...

It might get worse with the stock computer... it could make it run worse and send the other readings off in the wrong direction. This is where people get screwed on mail order type tuning, but the L67 guys didnt have much options other than this DHP computer until recently.

Its funny taking my camaro in, all lumpy as shit stinking like and old school bus... passes the plug in test with flying colors lol

My fav, pull forward after it passes on the rollers, and readjust the timing right there in front of them :D

[MurphysLaw88GT]

Its funny taking my camaro in, all lumpy as shit stinking like and old school bus... passes the plug in test with flying colors lol

I remember when you brought it in!:headbang

[MurphysLaw88GT]

You HAVE to pass the sniffer test now. Since you failed on it now you have to pass on it. It's already in their records. They wont even bother plugin it in and checking the diagnostic file now. They'll just throw it on the rollers right away.

It sucks but you sir are correct, you must pass the test type you fail in. For the GTP, it will now default to the IM240.

[WhiteZCamaro]

Its funny taking my camaro in, all lumpy as shit stinking like and old school bus... passes the plug in test with flying colors lol

I remember that too there was a very nice burnout to see afterwards!!!:thumbsup

[Poncho]

get a stock PCM and have tom tune it. thats my vote.

[Reverend Cooper]

nox can be egr related,coolant temp meaning if you have a pcm that runs the fan overtie to cool it down to fatten the system,or a cat issue. the heat and 93 will solve the prob. just do that with very little gas in the tank and it will pass then fill it up to dilutte the heat

[hotshift13]

Register it in jefferson county!!!! All my car are registered there except my wifes Volvo. I took her 89' Trans am in for the sniffer......it failed, I walked into the DMV and filled out the form and they gave me the stickers no qestions asked!!!

[Lash]

Register it in jefferson county!!!!!!!

Too late for that. He needed to change the registration before he failed...lol.
Now he's gotta pass no matter what.

[hotshift13]

I didn't have to change any hing except that where it says"county where vehicle is kept in" I put jefferson co. The car failed three times!! First time it was a little high in NOx, gave it a tune-up than it was worse!! Third time I used some stuff that gauranteed it to pass, well guess what.........it failed, Then the SES light came on and it turns out it has a faulty OXY sensor.

[hotshift13]

Guess I was lucky then that they didn't notice that it failed?? I guess I slipped through the cracks!!!!