Passed CA Emissions

[Z51JEFF]

Originally Posted by Hib Halverson

Wow...that's failed by a ton!

Unfortunately, if the engine is running right, 90-92 owners have few options as far as EGR because they don't have an EGR valve. Plus the State of California wants to force old cars off the roads and one way it does that is by lowering the emissions limits which has been done at least twice since 1995.

First, stop using octane booster. Few of them are effective and the ones that are (which use MMT as the active ingredient) can damage your cat converters.

Specifically, what brand of octane booster have you been using?

Secondly, I'd inspect the engine looking for anything that will increase combustion temperature which raises NOx emissions. Check the engine over and report back to the forum on your findings?

Lastly, can you post the full results of your test?

Cars running great with no VAC leaks or any problems.Is it possible the TECH got something fouled up with the test,the guy had a hard time getting a steady RPM reading,it was jumping around between 660 to maybe low 730 with no noticeable jumping idle in the motor.The guy did change the plug wire lead between #1 and other plug wires on the left bank.This is the second time Ive takin the car to this shop for the smog,these guys know Im a pain in the a$$ when it comes to the car so they are pretty patient with me so Ill take it back maybe Friday.Just changed the oil.Im going to clean the air filter and did get some octane booster,never used the stuff but will now if it helps.Ill give this a shot posting the results,might get jumbled.at 15 MPH,1276 RPM CO2 MEAS 14.30 02[%] MEAS 0.68 HC[PPM] MAX 78 AVE 38 MEAS 13 CO[%] MAX 0.72 AVE 0.08 MEAS 0.01 NO[PPM] MAX 545 AVE 261 MEAS 488.-25 MPH,RPM 2067 CO2%14.20 MEAS 0.82 HC[PPM] MAX 61 AVE 30 MEAS 9 CO[%]MAX 0.60 AVE 0.07 MEAS 0.00 NO[PPM] MAX 502 AVE 233 MEAS 702.

[Z51JEFF]

Im going to put the stock chip in the car.Maybe the 1-4 skip shift might help me get by.

[Hib Halverson]

It's hard to read those results, but it looks like you passed everywhere except NOx at 25.

Do not add octane booster.

Whether you put the stock cal in or not, ask the tech to try running the 25 mph test in a higher gear.

You passed (barely) NOx at 15 mph so it's possible, just by running a higher gear for the 25 test you can pass there, too.

Make sure you have clean, fresh gasoline from a station what pumps a lot of major brand fuel. Get the cats are freakin' hot before the guy runs the test. Highway driving in 4th gear or around the block a couple of times in first or second such that the engine runs mid-range rpm.

[mike100]

The engine is under less load at 25 mph if what you posted is true (2067 rpm). he kept you in first gear to help you out, but I bet your chip has too much timing advance coming in at 2k- so try to change that.

if it still won't pass, the NOx part of your catalyst is stuffed.

Also, the C02 should be 14.5% or better- that cat isn't working well because of too much HC/CO or a lean air leak- but most likely because of the accel enrichment and ign timing from a hot chip. If you run a cat rich for years on end, it will degrade them. That's why I made my calibration bone stock at cruise rpms and it only get up when you are actually getting on it.

[rhipsher]

This is the usual results I get every year. And that's with top end porting. When this was done the car had over 81k miles on it. Now it has 95k on it and the numbers were about the same. I don't know if most of our Z's run that clean or im just lucky.

[Z51JEFF]

Originally Posted by rhipsher

This is the usual results I get every year. And that's with top end porting. When this was done the car had over 81k miles on it. Now it has 95k on it and the numbers were about the same. I don't know if most of our Z's run that clean or im just lucky.

My car with 14,000 miles was 683 Nox at 2100 RPM and 25 MPH.Im trying to find the first test when the car had 6900 miles on it.Ive never really paid attention to the smog results,until now.

[Z51JEFF]

I just found the smog test when I bought the car with 6900 miles.The Nox level at 15 MPH and 1770 RPM was 488 and at 25 MPH and 1950 RPM the Nox level was 593.Based on some of the numbers Ive read from other members cars this was still on the high side.

[bdw18_123]

These are my results from my 140K mile Z:

[zr1don]

Change the chip back to stock, if that doesnt work, take out a couple more degrees timing advance in the testing rpm range. Like previously posted, dont use octane booster. running octane booster will cause a slightly lean condition until the computer redjusts to the new fuel mixture, which will drive NOx higher.

[zr1don]

Also, if the tech was having a hard time maintaining rpm, make sure the heater/ac control is set to off for the test. If it is on, the compressor can cycle on/off and the load change makes it very difficult to maitain rpm.