Passed CA Emissions

[GOLDCYLON]

Originally Posted by tf95ZR1

Wrapping the CATs- great idea!

Agree one of my biggest concerns with the Stainless HI Magnaflow Cats were that they would not get hot enough to pass emissions as they disapated heat rapidly. I am still sold that they can never pass the treadmill test as they have also out here in AZ. My suggestion to all my ZR-1 brothers out there is if you are running headers and need to pass a treadmill emission test to not buy the stainless highflows.

These Magnaflows as discussed are regular generic style cats that should pass but I like the wrapping idea. Frank where are you going with the CAGS? Last time I took the test I was aloowed the drive as the kid testing the car could not drive a standard.

[gbrtng]

Frank's right about CAGS - the original EPA tests were run with shifts at 15, 25 and 35 mph for 4-speed transmissions. So GM tricked the ZF to be a 4 speed if you shift out of first at 15 mph. The reason was to keep engine revs as low as possible to make the best EPA mpg numbers.

If roller emission tests are run at 15 and 25 mph, they should be in first and fourth gears, not just first.

[zr1don]

The cats I had installed on my first attempt to pass in August were high flow metallic substrate bullet cat (they wwere not thermowrapped), The cats I passed with are magnaflow ceramic substrate w/the thermowrap,

[tf95ZR1]

I know I'm bringing up an old thread, but now this (and more) is an issue for me. I didn't pass CA smog.
Same HC and CO values that passed for the last 5 years now don't pass. My NO was higher than before at 15mph but lower at 25mph(?).
So I'm researching all of this. My understanding is that HC and CO increase with poor/incomplete combustion,
while too hot a combustion increases NO. So there is a "window" of temperature and combustion that is ideal.
Won't wrapping and possibly overheating the CATS increase NO?

What to do, What to do... I know, move to another state.

[mike100]

burning oil, running, rich, lots of miles, will wear out a catalyst.

A lazy O2 sensor or a small air leak will skew the ability of the engine to run at the proper equilibrium to get a complete burn also.

more info like your test sheet data and how many miles you have would help.
my car passed for a rural area and would have failed here in San Diego Co (enhanced test area), but I found the problems and pre-tested it a few months back to ensure it can run clean.

[Hib Halverson]

California wants to force old cars off the road. It does that by changing the maximum limits for pollutants. It's been done three times since my 95 has been in the smog check starting in 2000. One of the cars this reduction sometimes impacts is the ZR-1 and it's usually oxides of nitrogen where the engine has trouble passing.

My car is registered in an enhanced smog check area of the State so I have to test on the chassis dyno at 15 and 25 mph. When I want to test in 2006, the car flunked NOx at 15 mph. Initially I couldn't understand why that happened because it had easily passed before and the engine was in good condition.

Later I learned the State was fooling with the max limits in order to flunk some cars which were marginal in their compliance even when they were in good condition and running well. In some cases were the owner cannot get a low-income exemption, the choices are scrap the vehicle or sell it out of state...exactly what California wants.

I spent a couple of days road testing the car and taking engine controls scan data and learned that the stock 93-95 calibration turns the digital EGR valve on at 17 mph. Getting my car to pass NOx at 15 mph was a simple as having an aftermarket calibration engineerwho knows how to change the closed loop parts of the cal change the EGR on from 17 to 14 mph. After that the car passed easily. Unfortunately, while this might be a solution for a 93-95 with EGR, it won't help a 90-92 which does't have EGR.

To correct some misconceptions about the Smog Check.

The standards are the same all over the state. They do not vary by geographical area. That said, the test, itself varies. The standard smog check is done with the car in neutral and the engine at idle and fast idle. The enhanced smog check is done on a chassis dyno at 15 and 25 mph. Enhanced areas are generally the urban ares of the state and a few rural areas with air quality problems.

Lastly, there was a post earlier in this thread about CAGS being for fuel mileage. It is true that CAGS offers an improvement in fuel economy, but that's not why the system was developed.

CAGS (for Computer-Aded Gear Selection) was developed as a way to get the ZR-1 through the Federal pass-by noise test. The test required the car to start in first gear, then shift to second and pass by the microphones at wide-open throttle. The way the test was structured had the car at an RPM which it made a lot of noise and to quiet it enough would have required a lot more exhaust restriction. A development engineer had an idea to use a computer controlled "gate" inside the transmission to lock out second gear and force a shift to fourth, ie: this made fourth temporarily second gear. Obviously this had the car going by the mics at a much lower rpm and making much less noise. CAGS enabled the ZR-1 to pass the pass-by noise test without a much more restrictive exhaust.

[mike100]

Originally Posted by Hib Halverson

California wants to force old cars off the road. ....

They have dyno test 5-gas in some semi-rural areas with higher limits. My car passed (barely) on NOx due to a vacuum leak and the original multec injectors. I fixed all of that and it will pass now. The Nox limit was 750 for the previous owner's zip code, but for me, the same level (around 500 I think) as the original posters smog sheet.

11:1 cars with no EGR need a little help, or a very healthy 3-way catalyst. A couple things I thought about are:

1) get the smog guy to test in first gear for the entire test to reduce engine load at 25mph if that is your problem spot. not sure if they can do that.
2) put 4:30's in the car to reduce engine loading and the combustion temps.
3) burn a chip with 1 or 2 degrees less timing at the load cells typically encountered on the rollers.
4) Have the man fudge the vehicle weight on the dyno to alter the load during the test (obviously not likely unless your man knows you).

[Coupe89]

Do you test with the stock chip?

[mike100]

I actually passed my unofficial pre-test with a haibeck chip- but not by a lot.

I have a mystery chip that is stock up until about 6000 rpm- that passed with flying colors on my then 28k mile 91.

I made a hybrid chip with stock everything below 2200 rpm- the range that the testing is conducted in.

[Paul Workman]

Originally Posted by Hib Halverson

CAGS (for Computer-Aded Gear Selection) was developed as a way to get the ZR-1 through the Federal pass-by noise test. The test required the car to start in first gear, then shift to second and pass by the microphones at wide-open throttle. The way the test was structured had the car at an RPM which it made a lot of noise and to quiet it enough would have required a lot more exhaust restriction. A development engineer had an idea to use a computer controlled "gate" inside the transmission to lock out second gear and force a shift to fourth, ie: this made fourth temporarily second gear. Obviously this had the car going by the mics at a much lower rpm and making much less noise. CAGS enabled the ZR-1 to pass the pass-by noise test without a much more restrictive exhaust.

Hib,

CAGS = noise abatement? Ya might wanna check your sources!

At the 2010 Bowling Green gathering, Dave McLellan went into detail with regard to the CALIFORNIA (not federal) PASS-BY NOISE TEST. There he explained to the audience in the big auditorium that the "POWER" switch was developed as a means to keep the secondaries from opening during the WOT pass-by test. It worked, obviously. However, the purpose evolved to become "officially" known as the "valet swich"; perhaps as a marketing scheme.

As for the CAGS, in his book Corvette From the Inside, Dave McLellan explains that in 1989 the CAGS switch was installed for fuel economy to assist the Corvette in the fuel economy testing to avoid the Federal "Gas Guzzler Tax".

P.