oldpro

my car has the secondary delete and am wondering if any of you have passed with the secondary delete .. I have the stock exhaust I can put on but am lacking other things . anyone guide me how to do this .

Z51JEFF

What are OTHER THINGS and are you asking somebody to help you with a bogus smog test,on an open forum? What state are you in,if it's Ca bone stock cars are having a lot of trouble passing.

Zrxmax

My local ZR-1 info enlightened friend has a chip burned with retarded timing ( as compared to stock ) for the testing rpm required for smog

testing. This knocks down the NOX level and usually solves the requirements to pass the sniffer / dyno test..

You might want to give Mark Haibeck a call and see if he has a remedy also.

Z51JEFF

My bone stock 91 failed twice at less than 20,000 original miles.

Zrxmax

When these LT5 engines / ZR-1s were EPA certified the emission requirements were not set at the same levels they are today. The standards that use to pass will no longer pass with the new rules.

Some people think the revised and more stringent CARB rules are designed to get older cars off the road.

Z51JEFF

That's exactly why they keep lowering the MAX LEVELS. My car at 7000 original miles tested around 700 MAX Nox level in 2007 when I first bought the car.

cv67

what are you lacking?
Changing headers out sounds like its getting done, aftermarket catback doesnt make a difference.
The way they tighten stds to become impossible is bs! Like thats going to drive someone to buy a new car that doesnt want one.
Guess someones gotta pay for the bailout even by force

Zrxmax

That is the standard operating procedure in the "testing for blow back" state we live in. Its a beautiful state run by those whom are following an agenda not created by or for the people.

Zrxmax

Investigate what a reprogrammed chip will do for emissions, specifically nox levels, and give that a try. AS I mentioned before call Mark Haibeck and get his opinion. I think Mark can help you get this sorted out.

oldpro

I may have found a solution . I am going to try to use my friends address in the owens valley as my living address and that way I don't have to test inyo county is the only county in ca that does not have to smog test . if that doesn't work then iwill have to put the car up for sale. to someone that lives where they don't have to pass smog . I just don't have the money to through at her to try to get her to pass. just one of the sad things about living on ssi.thankyou to all who responded .

carter200

Why don't you leave. I DID and never looked back!

oldpro

what kind of response is this what did I ever do to you . I was just being honest as to myn situation . the last thing I really want to do is get rid of the car I have had for 15 years. just got done rebuilding the engine and trans with zfdocs help . as well as the rear end suspension . I was looking for someone who might have helped me with maybe a cheap fix and it turned out not to be so . please if you cant be kind why not just keep it to yourself . have a nice day

oldpro

oh by the by if you left why are you responding

Z51JEFF

As somebody had already mentioned our friend in another State that deals with the LT5 can work some magic with a SPECIAL prom. -OTHERS- have used it as a last resort and I've been told it works. Now,I absolutely despise smog cheats,they're the reason Ca has made it so difficult on everyone but the only alternative to no using the smog prom is not having the car here in Ca. I figure if the a$$holes in Sac can keep dropping the max allowable limits than a little back door help will work. I know of a lot of people that can get a bogus smog,not for me and if I ever find a shop doing bogus smogs,I'll turn em in in a heartbeat.

wsaugenstein

I just bought my '91 in NJ in January, 2016. Since it's 25 years old, I registered it as an antique and don't have to pass any inspection or emissions tests. Does CA have such a law, and is your car old enough?

ZR-71

In Cali, only cars that are MY '75 and older are smog exempt.

Zrxmax

The bogus smog cheats make policy in Sacramento. Our cars were never designed to be placed on a dyno with a sniffer in the exhaust. What you are stating is like turning in the so called "cheaters" to the State run Mafia.

We aren't saving the planet with this draconian legislation while certain countries pollute the air with impunity.

Try some wisdom from George Carlin

Hib Halverson

LT5s have a hard time with the CA Smog Check, specifically the "enhanced smog check" used in many urban and suburban parts of the State.

The reason for this is that in the last 15 years or so, the State has been incrementally making the standards for passing the Smog Check more stringent as a way to force old cars with emissions which are close to the limit off the road. I know the standards have been toughened three times since the early 00s and it may have happened more often than that.

The most problematic ZR-1s are the 90-92s which lack an exhaust gas recirculation (EGR) valve. because the pollutant which LT-5s emit that is close to the limits is oxides of nitrogen or NOx and EGR valves reduce NOx. Since the early cars don't have EGR, they can't take advantage of an EGR valve's benefits.

The 93-95s, also, have a problem with the enhanced smog check but it's not quite as severe as the early cars. The late cars have an EGR valve–in fact LT5 in MY93 was the first GM use of a digital EGR valve. Most late cars should have no problem with the second part of the enhanced test (run at 25-mph) but they can have a problem with the first part (run at 15-mph) because the EGR enable speed in the ECM calibration is 17-mph. The solution is to have a tuner, such as Marc Haibeck, burn you a chip which turns the EGR on at 14-mph rather than 17-mph. It was my research back in the early-00s which discovered this solution. I had Ron Zimmer, one of the early LT5 tuners, do me a custom chip with a 14-mph EGR enable and I've never had another problem with my '95 and the Smog Check.

As for the early cars, if you're flunking because of NOx. There are some things you can do. First, if you have a very high-mileage engine and there are problems with ring seal, valve seal, oil use or excessive blowby, overhaul the engine.

If the engine is in good condition, but you can't pass, anything you can do to reduce combustion temperature and increase catalytic converter efficiency helps.

You need to minimize combustion chamber and piston top deposits because they drive up compression and increase NOx. Use of detergent-based injector cleaners and driving the car really hard for a period of time will help with that.

When you go to test, make sure you have fresh "top tier" fuel in the car. Make sure you have stock cats installed. Get the cats as hot as possible before you test. I've even gone as far as to set something up with the smog station such that I can drive around the block in first or second gear at 3000-4000 rpm which puts a lot of heat in the cats then once the coolant temp gets up there, I roll right into the test stall and let them test the car.

If your oxygen sensors are lazy, replace them. That said, you need a scan tester to detect that so, suffice to say, if your sensors have more than 50,000 miles and you're having trouble passing, buy new sensors.

If you have a high mileage car or have been using pour-in octane boosters, your cats might be performing poorly. If so, the only solution is to replace them. Problem is 90-92 cats aren't available. The only choice is one of the few companies which "rebuilds" cats by cutting them open, replacing the substrates then welding them back together.

cv67

Another vote for calling Mark maybe he can help out
If it just cant pass non op it and let er sit

having to do that with my 02 Silverado it wont unless I throw about 3k at it.

Are you having to go to a STAR station?

The manifold thing stinks for the 90s, current owner of my old Z wouldnt be allowed by the smog ref to use headers they made him either get the old cats rebuilt at least one of them. The other the smog ref found on some parts locater.

His car doesnt run or get driven now either.
This state I tell ya....other than the weather?

Hib Halverson

Secondary "delete" does effect emissions somewhat because, when you take out the port throttles, all the port velocities slow down at low throttle openings. Poor port velocity causes poor cylinder filling and poor mixture homogenity. Poor homogenity causes higher emissions.

You are just gong to have to try the Smog Check and see. As the smog station if it will do a "pre-test". Also, see my earlier post for the right things do do before you test.