KJL

First thing I am going to do is put stock chip back in. Should valet key be on or off during emmisions test? It is a 95 and has to be tested on the rollers. I think I will try another location as well. The car is stock only port work and exhaust and headers. Barely passed last year. This year I am 100 ppm over on NOx.

Coupe89

On my recent California SMOG test.
- I put the stock chip in.
- The key was on normal power.

My NOx were well over 100 ppm the limit.
Before the long drive:




What helped me also was to take the Z on a long drive. Over 100 miles to clear things out.

FASTAZU

Power key off, I always had to put the stock prom back in to get past emissions. The last two years it was fine after Marc did a dyno tune when the work was done.

ZR1Bob

If you have defeated the CAGS system via your chip to eliminate the skip ship, you need to put back a stock chip to reactivate it. According to Marc, the ZR-1s give a pop to the HC reading shifting between second and third, so a 1-4 shift eliminates that. When Illinois required roller testing, I always put my stock chip back in and always passed. --Bob

KJL

All-
Thanks for the input, i put the stock chip back in and failed even worse this time. The first time the numbers were 892 at 25 MPH and the 15/25 test at was 1005 ppm. Today at 25 mph it was 1200 ppm.

The car has been sitting with the exhaust Off since early spring. I will put some miles on it and check it again. I have two performance chips, one from Marc and one came with the car. It passed with the original performance chip but barely. Maybe when I try it again I will use that chip. Maybe I just need to replace the hi flow cats. Any recommendations?

I am heading out of town through 10/28 so it will have to wait.

Coupe89

Old fuel?

Z51JEFF

Go with the stock exhaust. -SOMEBODY- makes a PROM specifically to help with the smog BS. I have to jump through hoops to get my otherwise bone stock 24,000 mile 91 to pass. The car as it is now only has a KnN filter and open housing and a little performance upgrade from -SOMEBODY- When it's time to smog the car I put the stock air-cleaner in the car and switch out something. I'm not sure if Marc H makes a LEGAL prom for Ca.

KJL

Thanks for the tip. I just ask sombody if he can help me out....

I cant very well put my old exhaust back on, I have new headers and exhaust with all the EGR stuff removed which is not helping me but like I said, it did pass the last 2 years with the performance chip. It just hit me what the problem may be, I have always just barely passed, we are talking about by 1ppm! The guy at the emission station was very nice and showed me as the car speed increase, the Nox also increased.

I believe my new 4.10 rear gear is causing the car to run at a higher RPM at the test speeds which is has pushed me over the limit. There may be no fixing this other than to spend the required money (875.00) to attempt to fix for the exemption. Go figure.....

ZR1Bob

When roller testing my '93 in Illinois for many years, I always had a 4.10 rear, but maybe the requirements in Illinois were not as strict as where you are. Anyway, thankfully we don't have to do that anymore on older cars like the ZR-1s and even testing on newer cars like my 2010 BMW is done with just a plug in to the diagnostic port.--Bob

mike100

Make sure your oxygen sensors are new. Also, with headers the cats are far from heat of the head, but you might hit good numbers with good cats. running a stock chip is good, except if you have the 405hp engine, it was setup for EGR and without EGR, your NOx will surely be higher than without it.

What I would do is run a chip with stock fueling, fans set to come on at 205degrees (cool temps lower NOx), and maybe massage the ignition timing below 3500 rpm to be a little lower across all the load ranges over idle speed. Basically you would be pulling a VW to lower NOx.

Nox is caused by higher combustion temps or spikes in pressure during low speed lugging.

-less than new O2 sensors and not perfect fuel mixtures can elevate nox (lean run warmer).
-high compression, high coolant temps elevate NOx.
-too much ignition timing elevates NOx (aftermarket chips really don't help here at all).
-no EGR to puff cooler air when you crack the throttle which lower combustion temps.

try to fix as many of these items as you can address. Also, a 4.10 gear or asking the smog guy to not shift into second gear will lower the load on the engine too. Load = NOx.

KJL

I am thinking the higher rpm due to my 4.10 gears is hurting me. I have contacted and individual to see if a chip could be made to help me pass emissions. Hopefully I will hear back from him tonight. I am also thinking adding some dry gas to the tank. Alcohol should help the system burn cooler. So new cats, new O2 sensor, new chip, dry gas, fresh fuel..... if that doesn't do it, then it wont happen. Not re-installing the EGR crap that is for sure. In 3 more years it will be exempt. If that means blow 875 bucks for new stuff every year that I will sell on ebay until then, then so be it. It is worth every penny.

mike100

Your HC's and CO were about twice what mine did with a stock chip and newer o2 sensors. if it is chipped, it could be running a little enrichment at all speeds which is a common mod. Take the chip out. New O2 sensors will help for sure. The 4.10's will help- it reduces the amount of oomph to get rolling and the higher rpm at 15 and 25 mph will keep your cats a little hotter.

Also I ran factory LS7 cats on my headers, but I never tried to smog that because it would have failed visual here. But I couldn't smell any hydrocarbons when you were behind it. Universal cats are junk- that's why I used the 3" LS7 cats because they are chock full of rare earth catalyst metals and compact 3" units.

KJL

Do you have any info regarding the LS7 Cats? I have headers with aftermarket cats, 3" and I think about 10" long. They look at them with a mirror but have never been an issue regarding non stock. Most wouldn't know the difference.

KJL

Got her to pass.....what I learned, the intake plenum that I have is not stock. It does not have a provision for the EGR connection. The EGR solenoid is still there and wired but no plumbing.

I was considering water injection but thought before I did that I would try an "emissions" chip provided by a highly respected supporter of ZR1's and also run some CRC emissions system cleaner and burn up as much of the old fuel as possible. Put some fresh gas in and passed this time. My numbers were close at 25mph but she still made it.