Now that assachusetts had adopted california emissions standards, my car won't pass. It passed the HC and CO parts of the test, but failed the NOX. Here is what the printout said
Reading Limit
HC GPM: 1.06 1.20
CO GPM: 1.90 22.00
NOX GPM: 3.09 2.50


I dunno if that's considered close, or not. The HC is kind of close to the limit, and obviously the NOX is above the limit.

What could cause high NOX readings? I've heard some stuff about high combustion temps. The car was not warmed up for the test. I drove around for about half an hour on the highway before heading to the test station, but I had to wait 2 hours before they would inspect my car, so it sat all that time. The EGR valve is brand new, the 02 sensor is a year and a half old. The only culprit I can think of is my timing, which I know isn't set right... I think it's around 2 or 4 degrees advanced now, the stock setting is 6. The cat converter only has about 15,000 miles on it, it's a high flow Catco model. My oil has about 1500 on it, but it sat in the car all winter, from october to may, so I suppose it could be dirty (it's Mobil 1 btw). Anyways, I am pissed as hell every time I look at that ugly red R on my windshield... a cop magnet if there ever was one. any help will be much appreciated.

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91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter
ported TPI setup

Built on Wednesday

 

James, whats up bro?

I failed too man! God damn Massachusetts! The ironic thing is we have the same drivetrain and we both have Catco 3" cats w/ about 15K miles on them.... Here are my readings:

Reading Limit
HC GPM .32 1.20
CO GPM .41 22.00
NOx GPM 4.36 2.50

I'm going to run 89 octane, trim my timing down to 3-4*, and try blocking off one of my air filters. (I have K&N's.) You're right about NOx coming from high combustion temps. I also replaced my O2 sensor that had about 22K miles on it. I doubt either of us are running too lean, since for the most part we both keep them tuned well. When the ******* dynod my car, he did 7 runs for some reason, and it was up at about 240*. You should have seen the nice stripes of 275/40 Bridgestone rubber outside that losers garage after I had to look at that stupid R on my windshield! If I pass before you, I'll let you know what I did and what my new readings were. Nice seein you around bro, don't be a stranger, don't forget, I'm right up the street! (more or less)

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-Jason M. 1991 Camaro Z28

 

j- i just failed CT standerds for NOX as well... passed just fine last year, well under the limit with the same set up, only difference is the timing and the open element!! so, anyways, i am gonna throw the stock air cleaner on, and back off the timing to about 4* and i believe i will be fine.. i also have a catco cat.

steve

 

Mr. J,
TPI motors seem to run high on NOx emissions. At least all that I know of. It was one of the reasons that the 350/5-speed combo never made it to production(Too high NOx under deceleration).

Anyway, you said that your car was cold when you ran it through. That could be a factor since the EGR does not funtion until the engine is up to normal operating temperature. Also, there is an EGR temp sensor, and and EGR relay that may not be functioning. Is the computer going into closed loop mode? You should pass with stock timing. The last thing, but most likely not the culprit is carbon build up in the combustion chambers.




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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

I had the same problem in PA, EGR was well shot to say the least, EGR tem Diagnostic switch had also cracked and broke. On top of that the shop I took it to, trying to make a buck, pulled the AIR pump hose off the diverter! That AIR system made all the difference in the world for NOx!
I moved to texas though...no more CA emmissions for me! 350, BIG cam, Accell intake ,etc here I come!

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Corry Lazarowitz
clazarow@voicenet.com
clazarowitz@hotmail.com
1987 Pontiac Trans AM (GTA?) 350 or is it a 305?! TPI
SLP 1 3/4" headers, 3" cat back (stock cat
MSD ignition.
MSD Blaster SS coil.
3.73 Rear end gears
Accell 8.8 Wires
Bosh +4 Spark Plugs (Don't know if they really help but hell!)
Holley AFPR
Race Built Automatic trans ('vette servo, shift kit, tightly packed clutches)--just needs titanium gears now!
Newly gutted cat (the car gutted it's own cat!)
Hypertech Chip (Just found out I had it! :eek
More soon when funds are avail...

 

Jason he did the same **** when he did my car... he did 6 or 7 runs. The car was too cold when he did the first test, and was up over 230 and both fans were running by the time he was done. He was going to jack the car up by the y-pipe! I'm glad I was there in the garage the whole time he was doing it, the last time I had an inspection the moron jacked under the fender and caused it to bulge outward (which I had to fix myself). Man that is messed up that we both failed for the same exact thing. You think running lower octane gas will help? I know that the higher the octane, the more resistance the gas has to burning, so running lower octane gas should cause a more complete combustion, I guess. I think I may try some of that stuff they sell at Autozone, the stuff that is supposed to guarantee you'll pass emissions.

I don't think I'm running too lean... I don't have enough mods to be worrying about that yet. I had been using a quarter as shim in the FPR to boost fuel pressure by around 5 psi, but I removed that this winter upon learning that the stock PROM has these cars running a little rich from the factory. If I pass first, I'll be sure to let you know what worked for me.

anyways Jason we need to get together at some point this summer... you live right up I-95, it's a 15 minute drive for me.

------------------
91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter
ported TPI setup

Built on Wednesday

 

If it is CA emmissions like we had in PA, don't let them see you have an AFPR! That's not CA emmissions legal! Alot of stuff wasn't CA emmissions legal (At least thats what online catlogues (SP) have said! My MSD ignition coil came w/ a special sticker to say that it was C.A.R.B complient! What a PITA!

EDIT: The worst part about those emmissions laws is well, IT DIDN'T HELP THE AIR QUALITY! At least not in the Philadelphia area! Man I'm glad I'm outta there....I just hop Texas never imposes those stupid laws on me!


[This message has been edited by Corry (edited May 31, 2001).]

 

Main job of a catalytic convertor is to reduce NOx emissions...

It also helps to promote HC and CO to become H2O and CO2...

Make sure you have a good cat and one that isn't fried....

A good clean running motor and catalytic convertor will produce water that comes out of the muffler...

That shows that the convertor is doing its job and is not clogged up by extra fuel from a rich condition, or oil being blown through it.

 

My car fail horribly on its recent emissions test in Illinois. check out these stats
(Standard w/old 305)(my 87' Camaro w/350)
HC 2.00gpm 5.08
CO 30.0gpm 206.1
Co2 N/A 408.6

I have a feeling my 625 Demon Carb is the culprit, but after paying $300 for it I can't stand the idea of getting rid of it. Forunately for me in Illinois I can use some legal loop holes to get out of the test.

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Drew Veeneman
87' Camaro
Jasper Class II 350 (.3 over)
Stock auto 700r4
Snail like 2.73 gears
K+N
Road Demon 625cfm
Edlebrock headers
3" Cat+Flowmaster
Ugly olive drab camoflauge paint job