CAN'T PASS CALIF. SMOG, IDEAS/HELP!!!!

[tpr60]

Thanks Mike for the reference, that is the type of information that will be real helpful, now and later.

[Coupe89]

Do you have the stock prom in the car?
But your numbers looks lower then mine....

[tpr60]

Stock GM updated driveability prom used on the second pre test, stock prom used on the first test.

[Z51JEFF]

This is the fourth ZR-1 here in Ca that has failed that I know of.My 91 has 18,000 miles on the clock and it failed twice before I took it to a referee and it passed.Witrh tg first 2 smogs car had a Haibeck chip,open filter lid witsh a KnN filter.The last smog was bone stock new 02 sensors,its the Nox levels that are causing the problems.I suggest you join THE SEMA ACTION NETWORK.Ive got a number to call and ask if anything is being done to help owners that cant pass.In 4-2011 the state lowered the max limits in an effort to get older cars off the road.How would I find out what the smog levels were when the car was new?After I failed twice I dug out some of my past smog paperwork and my car with 6000 miles tested at over 500 PPM at the Nox levels.

[tpr60]

Update, my buddy and I did a leak down test on the Z today to rule any possible internal engine problems. Passed with all cylinders showing 3 to 7% leakage. Waiting for some thermal wrap to show up and I will wrap the cats to keep the heat in for my next smog pre test. Keep your fingers crossed!!!

[tpr60]

=D>SHE PASSED the smog test today!!!! After thermal wrapping the cats, new o2 sensors, propane testing for intake leaks we pre tested the Z, would pass the 2500rpm test but failed the idle test for HC ppm. Sh---t!!!. That was last Thursday. Put the car on my lift and removed the manifold/cat assembly, guess what I found??? Someone gutted the cats, no honeycomb at all. 12 hours later both used cats I got from Pete in Ill. were installed. Official smog test showed only 3ppm at both idle and 2500rpm, and 0 CO's, so clean you could breath the exhaust. WAH HOOOO!!

[mike100]

with 11% CO2, I knew you had a bad cat, but it seems these cars really do like a fresh O2 sensor(s). Mine will pass current testing thresholds, but I bet I could get a 10 percent improvement with a new pair of sensors.

Where did you get yours from?

[tpr60]

Mike, I get my ACD parts from my local parts house that I used when I was a GM parts manger, so there is a good working relationship. Took the # off the old Bosch O2 sensor and matched it with the same # on the new sensor. The parts catalog shows only one use but we know there is one on each cat.

[bdw18_123]

Originally Posted by tpr60

...Put the car on my lift and removed the manifold/cat assembly, guess what I found??? Someone gutted the cats, no honeycomb at all. ...

One of my cats was the same way, nothing in there at all. The other side was still intact, so I think in my case the catalyst on one side just got worn out and then probably broke up and got blown out of the exhaust at some point.

[Z51JEFF]

Originally Posted by mike100

with 11% CO2, I knew you had a bad cat, but it seems these cars really do like a fresh O2 sensor(s). Mine will pass current testing thresholds, but I bet I could get a 10 percent improvement with a new pair of sensors.

Where did you get yours from?

The sensor on the right side is a nightmare to plug in,be prepared to breakout the -special tools- for this one.In my case it was a stiff wire and some sticky dumb-dumb,also known as seam sealer stuck on the end of the stiff wire to help get the 02 plug started.